University School of Physical Education in Wrocław University School of Physical Education in Kraków

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1 University School of Physical Education in Wrocław University School of Physical Education in Kraków vol. 14, number 3 (September), 2013

2 University School of Physical Education in Wrocław (Akademia Wychowania Fizycznego we Wrocławiu) University School of Physical Education in Kraków (Akademia Wychowania Fizycznego im. Bronisława Czecha w Krakowie) Human Movement quarterly vol. 14, number 3 (September), 2013, pp Editor-in-Chief Associate Editor Alicja Rutkowska-Kucharska University School of Physical Education, Wrocław, Poland Edward Mleczko University School of Physical Education, Kraków, Poland Editorial Board Physical activity, fitness and health Wiesław Osiński University School of Physical Education, Poznań, Poland Applied sport sciences Zbigniew Trzaskoma Józef Piłsudski University of Physical Education, Warszawa, Poland Biomechanics and motor control Tadeusz Bober University School of Physical Education, Wrocław, Poland Kornelia Kulig University of Southern California, Los Angeles, USA Physiological aspects of sports Andrzej Suchanowski Medical University of Bialystok, Białystok, Poland Psychological diagnostics of sport and exercise Andrzej Szmajke Opole University, Opole, Poland Advisory Board Wojtek J. Chodzko-Zajko University of Illinois, Urbana, Illinois, USA Gudrun Doll-Tepper Free University, Berlin, Germany Józef Drabik University School of Physical Education and Sport, Gdańsk, Poland Kenneth Hardman University of Worcester, Worcester, United Kingdom Andrew Hills Queensland University of Technology, Queensland, Australia Zofia Ignasiak University School of Physical Education, Wrocław, Poland Slobodan Jaric University of Delaware, Newark, Delaware, USA Toivo Jurimae University of Tartu, Tartu, Estonia Han C.G. Kemper Vrije University, Amsterdam, The Netherlands Wojciech Lipoński University School of Physical Education, Poznań, Poland Gabriel Łasiński University School of Physical Education, Wrocław, Poland Robert M. Malina University of Texas, Austin, Texas, USA Melinda M. Manore Oregon State University, Corvallis, Oregon, USA Philip E. Martin Iowa State University, Ames, Iowa, USA Joachim Mester German Sport University, Cologne, Germany Toshio Moritani Kyoto University, Kyoto, Japan Andrzej Pawłucki University School of Physical Education, Wrocław, Poland John S. Raglin Indiana University, Bloomington, Indiana, USA Roland Renson Catholic University, Leuven, Belgium Tadeusz Rychlewski University School of Physical Education, Poznań, Poland James F. Sallis San Diego State University, San Diego, California, USA James S. Skinner Indiana University, Bloomington, Indiana, USA Jerry R. Thomas University of North Texas, Denton, Texas, USA Karl Weber German Sport University, Cologne, Germany Peter Weinberg Hamburg, Germany Marek Woźniewski University School of Physical Education, Wrocław, Poland Guang Yue Cleveland Clinic Foundation, Cleveland, Ohio, USA Wladimir M. Zatsiorsky Pennsylvania State University, State College, Pennsylvania, USA Jerzy Żołądź University School of Physical Education, Kraków, Poland Translation: Michael Antkowiak, Tomasz Skirecki Design: Agnieszka Nyklasz Copy editor: Beata Irzykowska Statistical editor: Małgorzata Kołodziej Proofreading: Joanna Pogroszewska Indexed in: SPORTDiscus, Index Copernicus, Altis, Sponet, Scopus, CAB Abstracts, Global Health 8 pkt wg rankingu Ministerstwa Nauki i Szkolnictwa Wyższego Copyright 2013 by Wydawnictwo AWF we Wrocławiu ISSN Editorial Office Dominika Niedźwiedź Wrocław, al. Ignacego Jana Paderewskiego 35, Poland, tel , hum_mov@awf.wroc.pl This is to certify the conformity with PN-EN-ISO 9001:2009 Circulation: 160

3 2013, vol. 14 (3) contents physical activity, fitness and health Thiago A.C. Oliveira, Renata A. Denardi, Go Tani, Umberto C. Corrêa Effects of internal and external attentional foci on motor skill learning: testing the automation hypothesis Teresa Sławińska, Paweł Posłuszny, Krystyna Rożek The relationship between physical fitness and quality of life in adults and the elderly Aleksandra Stachoń, Jadwiga Pietraszewska Body composition in male physical education university students in view of their physical activity level Jakub Łabudzki, Tomasz Tasiemski Physical activity and life satisfaction in blind and visually impaired individuals applied sport sciences Soňa Jandová, Jan Charousek Laterality of lower limbs during V2 Alternate in Nordic combined athletes Krzysztof Karpowicz, Małgorzata Karpowicz Reflections on the changes observed in the structure of motor skills in young athletes biomechanics and motor control Jonathan Sinclair, Lindsay Bottoms Methods of determining hip joint centre: their influence on the 3-D kinematics of the hip and knee during the fencing lunge Luciano Pavan Rossi, Rafael Pereira, Michelle Brandalize, Anna Raquel Silveira Gomes The effects of a perturbation-based balance training on the reactive neuromuscular control in community-dwelling older women: a randomized controlled trial physiological aspects of sports Paulina Hebisz, Rafał Hebisz, Marek Zatoń Changes in breathing pattern and cycling efficiency as a result of training with added respiratory dead space volume psychological diagnostics of sport and exercise Artur Magiera, Robert Roczniok The climbing preferences of advanced rock climbers Zuzanna Wałach-Biśta A Polish adaptation of Leadership Scale for Sports a questionnaire examining coaching behavior Publishing guidelines Regulamin publikowania prac

4 2013, vol. 14 (3), Effects of internal and external attentional foci on motor skill learning: testing the automation hypothesis doi: /humo Thiago A.C. Oliveira *, Renata A. Denardi, Go Tani, Umberto C. Corrêa University of São Paulo, São Paulo, Brazil Abstract Purpose. This study investigated if (1) the beneficial effects of an external focus of attention on learning a motor skill were influenced by an internal focus of attention provided at initial instruction (2) or by an internal focus of attention at the early stage of the acquisition phase and (3) their relation to the automation hypothesis. Methods. Three separate experiments were performed with 168 college students on the acquisition, transfer, and retention of a golf-putting task. Results. In conjunction, the results of the three experiments pointed to the positive effects of an internal attention of focus instructions followed by an external attentional focus on motor learning. Conclusions. These results support the development of an alternative hypothesis on the effects of attentional focus on motor skill acquisition. Key words: instruction, attention, motor learning, golf, external focus, internal focus Introduction Attention is an intriguing aspect of human behavior. When performing activities of daily living, humans encounter numerous situations in which they need to choose how, where, and when to focus their attention in order to be efficient. Attention has been referred to as a basic mechanism that allows for the selection of information, and it is closely related to concepts such as concentration, consciousness, mental effort, direction, excitability, and ability [1]. For over a century, researchers have developed models and theories to explain the limited attentional capacity of individuals, how they simultaneously or sequentially deal with various stimuli, and how they direct attention to relevant sources of information [2 6]. In the last few years, investigation on the performance and learning of motor skills has focused on the internal (i.e., movement patterns) and external (i.e., environmental characteristics) aspects of a task [7]. The results of this body of research have highlighted the superiority of external focus of attention on the performance and learning of motor skills in comparison to those based on internal focus and control (no attentional focus) [5, 8 14]. The main explanatory hypothesis for this is that the adoption of an external rather than internal focus of attention promotes greater automaticity in movement control [7]. It also has been suggested that the early stages of learning are shortened by the use of external foci [5, 7, 8]. Furthermore, it has been recognized that motor skill learning is characterized by a process that occurs in phases. For instance, the classical model by * Corresponding author. Fitts and Posner [15] describes motor learning as three phases: cognitive, associative, and autonomous. In the first phase, the learner seeks to understand the task goal, but his/her attentional mechanisms are overloaded causing errors and inconsistent performance. In the subsequent phase (associative), the learner becomes able to associate with the movement and environmental information necessary to achieve the goal of the skill. As a result, the amount of error is diminished. The attentional requirements also significantly decrease as a result of a decrease in the variability of performance. Finally, the skill becomes automatic or learned (autonomous phase), that is, performance occurs under little or no influence from attentional demand. In other words, in this phase, the learner acquires the capability to cope with other relevant aspects of the task as processing becomes automatic and the level of conscious control of the task is diminished [6]. Of considerable interest is that the results in a number of aforementioned studies on the benefits of external foci did not take into account the previous introduction of internal foci. Specifically, in some studies, participants received instructions about the proper technique for completing the task prior to the experimental phase [5, 9, 11, 12], or had the opportunity to become familiar with the technique in practice trials [5, 11 13], which can be characterized as a source of internal foci. For example, Wulf [9] conducted a study to determine the influence of internal and external foci of attention on the learning of a golf swing. Twenty-two inexperienced students performed a golf swing task by hitting a circular target located 15 meters away. Participants in the internal focus group received information about the technique of the movement (a swinging motion of the arms) while those in the external focus group received information about club movement (performing a pendulum-like motion 194

5 T.A.C. Oliveira, R.A. Denardi, G. Tani, U.C. Corrêa, Attentional focus effects on motor skill learning with the club). However, before the beginning of the practice phase, the experimenter explained and demonstrated the basic technique of the golf swing. All participants were given the same instructions on grip, stance, and posture. The results showed better performance by the external than the internal attentional focus groups in the retention test. Given that information about a skill s technique, and, therefore, its movement pattern, refer to internal focus [7], we hypothesized that the beneficial effects of an external focus of attention on learning a motor skill could be influenced by an internal focus of attention provided during initial instruction, or even by an internal focus of attention at the earlier stages of the acquisition phase. These hypotheses were investigated by two experiments by also using a golf swing task. In a third experiment, we sought to investigate the effects of internal and external foci of attention on motor skill learning with regard to the aforementioned automation hypothesis. That is, as Wulf [7] observed, the adoption of an external rather than an internal attentional focus promotes greater automaticity in movement control. Interestingly, within a relatively large number of studies carried out so far, only McNevin and Wulf [10] and Poolton, Maxwell, Masters, and Raab [16] tested the automation hypothesis. However, these studies were not without their limitations, since Poolton, Maxwell, Masters, and Raab [16] did not consider the control group, and McNevin and Wulf s [10] conclusions were not restricted to their results. Experiment 1 This experiment investigated whether the effects of an external focus of attention would be influenced by information based on an internal focus of attention provided during initial instruction. Material and methods Sixty college students (34 females and 26 males; M age = 23.4 y, SD = 5.6 y) were randomly selected. None had any experience with the motor task (golf putting), which allowed us to study the learning process considering all of its phases. Nonetheless, it is important to clarify that the participants were chosen as previous studies on attentional focus also used college students and that this population was deemed capable of completing the task and experimental procedures. The participants provided their written informed consent and the experimental protocol was performed in compliance with the guidelines of the American Psychological Association and approved by experimenter s university ethics committee. The design and procedure of the task was based on previous studies [9, 11, 16] and, additionally, on a previously completed pilot study. The motor task selected was the golf putt [9, 11], performed on a mini-golf putting green 5 m long and 1.5 m wide located in a closed room, with a hole as the target (with a diameter of 10.8 cm) at the end of the green. This design was similar to the one used by Poolton, Maxwell, Masters, and Raab [16]. Additional equipment included two golf clubs (putters), 10 golf balls, and a laptop computer for data collection. The golf putting task was performed by each participant one at a time. The participants were randomly distributed into two internal focus (IF) groups and two external focus (EF) groups. The groups received the following instruction during the acquisition phase, for the IF groups they were directed to keep their attention specifically on the movement of the trunk and try to keep a straight path with the torso, while the EF groups were asked to direct their attention specifically to the head of the club and try to keep a straight path with the torso. All groups watched a video of an athlete performing three putting shots. Afterwards, one group from each type of focus received additional instructions based on internal focus of attention via video by being told how important it is to move the torso in a straight path. These subgroups were designated as IF-EF and IF-IF. The experimental design involved three phases: acquisition, transfer, and retention. All groups performed ten blocks of ten trials in the acquisition phase. A fiveminute interval between each block was provided. In this phase, the stroke was performed from a distance of 3 m from the target. The transfer test involved performing two blocks of ten trials, with no instruction provided, but at a larger distance to the target (3.5 m). The retention test was performed exactly the same as the transfer test but took place seven days after the acquisition phase. At the end of the experiment all participants completed a questionnaire about where they directed their attention in order to determine whether or not it was done in accordance with the request of the experimenter. For data analysis, hitting the ball into the target (hole) was treated as the dependent variable. Hits were registered in Microsoft Excel and analyzed in blocks of ten trials based on performance accuracy (number of balls hit in the hole) and variability (coefficient of variation). Performance by each group in the acquisition phase was analyzed using one-way ANOVA. Learning was assessed using the first and last blocks of the acquisition, transfer, and retention phases by two-way ANOVA (groups blocks). Observed effects were further analyzed using Tukey s Honestly Significant Difference (HSD) posthoc test. For all analyses, the level of significance was set at p < Statistical analysis was performed with Statistica 9.0 software (Statsoft Inc., USA). It was hypothesized that the group provided with internal focus of attention during initial instruction followed by an external focus of attention during the practice (acquisition) phase would achieve the best results in learning the skill. 195

6 T.A.C. Oliveira, R.A. Denardi, G. Tani, U.C. Corrêa, Attentional focus effects on motor skill learning Results Concerning the performance accuracy in the acquisition phase, one-way ANOVA revealed main effects for groups IF F(9, 126) = 4.38, p < 0.01, ŋ 2 = 0.24, IF-IF F(9, 126) = 8.31, p < 0.01, ŋ 2 = 0.37 and IF-EF F(9, 126) = 18.75, p < 0.01, ŋ 2 = Post-hoc tests indicated that these groups significantly improved their performance in the acquisition phase. No differences were found for the EF groups. For learning, two-way ANOVA (4 6) revealed an interaction between groups and blocks F(15, 280) = 2.03, p < 0.01, ŋ 2 = It was verified that only the IF-EF group performed better in the transfer and retention tests than at the beginning of the acquisition phase (Fig. 1). With regards to performance variability in the acquisition phase, one-way ANOVA revealed main effects for EF F(9, 126) = 2.10, p < 0.05, ŋ 2 = 0.13, IF-IF F(9, 126) = 1.95, p < 0.05, ŋ 2 = 0.12, and IF-EF F(9, 126) = 2.98, p < 0.01, ŋ 2 = Post-hoc tests indicated that variability increased in the first sets of blocks during acquisition but then decreased in subsequent blocks. No differences were found for the IF group. Additionally, no differences were revealed for learning by two-way ANOVA (Fig. 1). Discussion Several studies have indicated that learning with external foci is more effective than learning with an internal focus of attention [5, 8 14]. However, we understand that these studies had introduced internal foci prior to using external foci as their participants received Figure 1. Mean number and coefficient of variation of hits in blocks of ten trials during the acquisition (A), transfer (T), and retention (R) tests of the four groups (IF, EF, IF-EF, IF-IF) in Experiment 1 information about the technique of the specific skill to be learned during initial instruction. Based on these aspects, we asked whether the prior introduction of an internal focus of attention would be something essential for learning, or rather, a pre-requisite for the effects of an external focus of attention to be effect on the learning of a motor skill. Interestingly, the results of this experiment support this hypothesis. That is, the group with an internal focus of attention in instruction, followed by an external focus in the acquisition phase, was the only group that exhibited the best learning of the skill. A possible explanation for this result is related to the earlier stages of the learning process, but one that is not in accordance with Wulf s hypothesis [7], where an external focus leads to an acceleration of the learning process. Instead, it is believed that the internal focus may have contributed to the learning of skills in the earlier stages of learning. Thus, when the external focus of attention was introduced, the internal focus had already made it possible for the learners to understand what was to be done [15] or possibly even acquired the knowledge of the required movement [17]. Experiment 2 This experiment investigated whether or not the efficacy of an external focus of attention is dependent on prior practice with an internal focus of attention. Material and methods Sixty college students (21 females and 39 males; M age = 19.8 y, SD = 7.7 y), with no experience with the selected task were selected. Other aspects of the method (task, material, procedures, and data analysis) were similar to that in Experiment 1. No specific instruction was given before the beginning of the experimental phase. The participants were distributed into four groups: those with an internal focus (IF) and external focus (EF) of attention during the acquisition phase, those provided with an internal focus in the first fifty trials followed by an external focus in the last fifty trials (IF-EF), and a group provided with an external focus of attention in the first fifty trials followed by internal focus in the last fifty trials (EF-IF). This was followed by transfer and retention tests similar to those in Experiment 1. The hypothesis set forward in this experiment was that the group experiencing an internal focus before an external focus of attention during practice would achieve better results in terms of learning the skill than those without the prior internal focus of attention. Results In the acquisition phase, significant differences were revealed by ANOVA for all groups: groups IF F(9, 126) 196

7 T.A.C. Oliveira, R.A. Denardi, G. Tani, U.C. Corrêa, Attentional focus effects on motor skill learning results allow one to reinterpret previous findings on the benefits of EF on motor skill learning. It seems that the efficacy of task performance increased in some studies [5, 7, 12] due to the participants being provided with an opportunity to become familiar with the task via the introduction of a prior internal focus of attention before practicing it with an external focus of attention. Based on the results, it can be assumed that what promoted learning in the golf putter task was practice with an internal focus prior to practicing with an external focus of attention. The rationalization of these results is similar to that in Experiment 1, i.e., the internal focus of attention augmented performance in the earlier stages of learning by contributing to the understanding of the goal of the task [15] and/or the idea of the movement [17]. Thus, when an external focus of attention was introduced in the second half of practice, the learners could associate it with information on the movement pattern necessary in order to achieve the goal of the task. Figure 2. Mean number and coefficient of variation of hits in blocks of ten trials during the acquisition (A), transfer (T), and retention (R) tests of the four groups (IF, EF, IF-EF, IF-IF) in Experiment 2 = 4.78, p < 0.01, ŋ 2 = 0.25; EF F(9, 126) = 12,10, p < 0.01, ŋ 2 = 0.46; IF-EF F(9, 126) = 23.13, p < 0.01, ŋ 2 = 0.62; and EF-IF F(9, 126) = 27.25, p < 0.01, ŋ 2 = Post-hoc analysis found that all groups improved their performance in the acquisition phase. Similar to Experiment 1, the results of two-way ANOVA for learning revealed an interaction between groups and blocks trials F(15, 280) = 1.77, p < 0.05, ŋ 2 = Tukey s HSD test revealed that the IF, EF, and EF-IF groups improved their performance during the acquisition phase, but in the transfer and retention tests their rate of performance decreased to the original baseline. Group IF-EF was the only one that maintained their performance level in the transfer and retention tests (Fig. 2). Regarding variability, in the acquisition phase significant differences were revealed by ANOVA only for groups IF-EF and EF-IF at F(9, 126) = 2.44, p < 0.05, ŋ 2 = 0.15 and F(9, 126) = 3.80, p < 0.01, ŋ 2 = 0.21, respectively. For both groups the post-hoc results showed that variability increased from the beginning to the middle of the acquisition phase and then afterwards decreased. In relation to learning the skill, two-way ANOVA revealed effects only for blocks of trials F(3, 280) = 5.19, p < 0.01, ŋ 2 = Tukey s HSD test revealed that variability among the groups increased between the first acquisition block and the transfer and retention tests (Fig. 2). Discussion This experiment aimed at investigating whether practice under IF-EF would promote better learning when compared to other the forms of attentional focus. The Experiment 3 The final experiment focused on Wulf s hypothesis by investigating the effects of internal and external attentional foci on motor skill automation. Material and methods This group was comprised of 48 college students (23 females and 25 males; M age = 25.7 y, SD = 5.8 y). None of the participants had any experience with putting. The task, material, and procedures were similar to those in Experiment 1. The experiment involved two experimental phases: acquisition and retention. All participants practiced the golf putting task during the acquisition phase in ten blocks of ten trials each. The retention test was conducted 48 hours after the acquisition phase and involved completing ten trials. The participants were divided into two groups of internal focus (IF) and two groups of external focus (EF) of attention. At the end of the acquisition phase, during the last block of trials, an additional task (distraction) was introduced to all groups, where the participants were asked to say the name of a loved one out loud simultaneously when executing the golf putt. After the acquisition phase, one group of each type of focus performed the retention test with the distraction task while the others did not. Statistical analysis of the acquisition phase was similar to that in the previous experiments, employing 4 4 ANOVA (groups blocks) followed by Tukey s HSD test. It was assumed that if an external focus of attention would facilitate automation during skill acquisition, the distraction task would not degrade the performance of the EF groups in any of the conditions. 197

8 T.A.C. Oliveira, R.A. Denardi, G. Tani, U.C. Corrêa, Attentional focus effects on motor skill learning Results With regard to performance in the acquisition phase, one-way ANOVA revealed effects for all groups: IF with the distraction task during the retention test, F(9, 99) = 8.55, p < 0.01, ŋ 2 = 0.44; IF without the distraction task during the retention test F(9, 99) = 4.55, p < 0.01, ŋ 2 = 0.29; EF with the distraction task during the retention test F(9, 99) = 8.55, p < 0.01, ŋ 2 = 0.40; and EF without the distraction task during the retention test F(9, 99) = 4.96, p < 0.01, ŋ 2 = Post-hoc analysis indicated that the groups improved in terms of performance in the acquisition phase until the ninth block, where their performance worsened from the ninth to the tenth block (Fig. 3). With regards to learning, two-way ANOVA revealed significant differences only for blocks F(3, 132) = 36.04, p < 0.01, ŋ 2 = Tukey s HSD indicated that performance improved from the first to the ninth acquisition block (p < 0.01). For the subsequent blocks (tenth and the retention test), performance diminished (p < 0.01). With regard to the variability of performance in the acquisition phase, one-way ANOVA revealed effects for only two groups: IF with the distraction task during the retention test F(9, 99) = 2.29, p < 0.05, ŋ 2 = 0.17 and for EF without the distraction task during the retention test F(9, 99) = 2.38, p < 0.05, ŋ 2 = Post-hoc analysis indicated that variability among the groups increased in the acquisition phase until the ninth block. Two-way ANOVA on learning did not reveal any significant differences (Fig. 3). Discussion The aim of this experiment was to test the hypothesis that learning with an external focus of attention could lead to automation of a skill [7]. It was expected that the introduction of the distraction task would not disturb those groups with an external focus of attention, or if it did, it would distract them less than for the IF groups. This was considered to be likely due to the characteristics of automation: learners can direct attention to aspects other than those of task execution [6]. Additionally, as was suggested by Poolton, Maxwell, Masters, and Raab [16], the adoption of an external focus of attention might promote lower overload of working memory. However, the results found a lack of differences between the groups at the end of the acquisition phase and that the introduction of the distraction task had the learners performing at a level similar to the one during the earlier phase. Interestingly, this was maintained even in the retention test. A decrease in performance with the introduction of a new task is expected in a non-redundant system. According to the theory of central resource capacity [18], when two activities compete between themselves for attentional resources, the system can suffer. As a consequence, one of the conditions (performing the golf putting stroke or saying the name of a loved one out loud) might not be met with the required amount of attention and the activity cannot therefore be successfully completed [18]. As the results of the present experiment indicated, performance returned to the initial level at the tenth block of trials. Thus, it could be hypothesized that the learners did not reach a state of automation, as that would have allowed them to handle having their attention divided. The results of this experiment do not support the current literature on the subject [5, 7, 8, 10] in the sense that external focus did not promote skill automation among the participants. Conclusions Figure 3. Mean and coefficient of variation of hits in blocks of ten trials during the acquisition (A) and retention (R) tests of the four groups in Experiment 3 In the acquisition of motor skills, individuals must manage receiving numerous types of information in order to perform a task successfully. For instance, in order to perform the putting stroke, a golfer has to cope with information such as body movement, proper hand grip on the club, the ball s trajectory, the force used for the shot, and maintain focus on the target. This makes a somewhat simple motor skill seem relatively difficult [19]. The question then stands, how can it be possible to organize a practice procedure that could promote an efficient learning process? An answer to this question has emerged from experimental research on attentional focus, including studies on the effects of internal and external focus on attention on motor skill acquisition [7]. These studies results have suggested that an external focus has a better effect on motor learning than internal focus of attention. The 198

9 T.A.C. Oliveira, R.A. Denardi, G. Tani, U.C. Corrêa, Attentional focus effects on motor skill learning main reasoning behind this is that external attentional focus facilitates automation of movement control and can shorten the initial stages of learning in such a way that a learner can achieve automation stage more quickly [7 8]. However, it seems that these findings have not taken one important fact into consideration: in much of the literature, learners received instructions with an internal focus of attention before that of an external focus [e.g. 5, 9, 11 13]. This was the main concern of the present study. We questioned whether the positive effects of an external focus of attention on motor learning could be influenced by the previously introduced internal focus of attention. The results of this study support our hypothesis. In Experiment 1, it was observed that motor learning occurred only in the group that received information related to an internal focus of attention when initially being provided with instruction and then an external focus of attention during the acquisition phase. Similar results were observed in Experiment 2, in which an internal focus preceded an external focus of attention in the acquisition phase. Additionally, in Experiment 3, the results indicated that the realization of the automation stage was not facilitated by an external focus of attention. These results refute the findings and hypotheses from the literature on attentional focus [7] and provide support to the proposition that motor skill learning occurs through an internal focus of attention in the initial instruction or acquisition phase, and then followed by an external focus of attention. As previously described, an alternative hypothesis for this proposition is that internal focus provides learners with comprehension of the task goal and/or that they are able to understand the idea of the movement (i.e., what is practiced in the first stage of the learning process) [15 17]. As a result, learners are better able to handle information from an external focus of attention as they can associate this information with that of the movement pattern, which is necessary for the successful performance of the task. The results of the present study point to the positive effects of an internal focus of attention, followed by an external attentional focus, on motor learning. It is believed that these results can open the door for the development of an alternative hypothesis on the effects of attentional focus on motor skill acquisition. However, caution is advised when interpreting the results presented here, as although they were based on inferential statistics at a p value of 0.05, complementary descriptive statistics showed small effect size. Thus, performing additional studies similar to the one presented here is needed in order to confirm the results reproducibly. 4. Broadbent D.E., Perception and communication. Pergamon, London Bell J.B., Hardy J., Effects of attentional focus on skilled performance in golf. J Appl Sport Psychol, 2009, 21 (2), , doi: / Schneider W., Shiffrin R.M., Controlled and automatic human information processing: I. Detection, search, and attention. Psychol Rev, 1977, 84 (1), 1 66, doi: / X Wulf G., Attentional focus and motor learning: A review of 10 years of research. E-Journal Bewegung und Training, 2007, 1, Wulf G., Hoß M., Prinz W., Instructions for motor learning: Differential effects of internal versus external focus of attention. 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Exp Brain Res, 2012, 217 (2), , doi: /s Fitts P.M., Posner M.I., Human performance. Brooks Coole, Belmont Poolton J.M., Maxwell J.P., Masters R.S.W., Raab M., Benefits of an external focus of attention: Common coding or conscious processing? J Sport Sci, 2006, 24 (1), 88 99, doi: / Gentile A.M., A Working model of skills acquisition with application to teaching. Quest, 1972, 17 (1), 3 23, doi: / Kahneman D., Attention and effort. Prentice-Hall, Englewood Cliffs, New Jersey Piekarzievcz L.E., Effects of increased extrinsic feedback in learning a motor skill locked [in Portuguese]. Dissertation. Department of Physical Education, Division of Biological Sciences, Paraná University, Brazil Paper received by the Editors: April 22, 2013 Paper accepted for publication: July 11, 2013 References 1. Schmidt R.A., Lee T.D., Motor Control and Learning. Human Kinetics, Champaign James W., The principles of psychology (2). 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10 2013, vol. 14 (3), The relationship between physical fitness and quality of life in adults and the elderly doi: /humo Teresa Sławińska *, Paweł Posłuszny, Krystyna Rożek University School of Physical Education, Wrocław, Poland Abstract Purpose. The aim of this study was to determine the relationships between physical fitness and various aspects of quality of life in middle-aged adults and the elderly. Methods. The sample included 216 women and 43 men, living in a medium-sized city in Poland aged years. Physical fitness was determined using a test battery specifically designed for the elderly (Senior Fitness Test); grip strength by the dominate hand was also measured. The short form of the WHOQOL-BREF questionnaire was used to evaluate quality of life. Four domains (physical, psychological, social relationships, environment) of quality of life as well as overall quality of life and health were self-assessed. Results. Among the selected components of physical fitness measured in the study, the assessment of overall quality of life in women was related to upper limb strength and, depending on the quality of life domain, also with upper or lower body flexibility. In men, the only factor influencing their overall assessment was upper body flexibility, whereas cardiorespiratory efficiency was the only factor influencing their detailed self-assessment of the physical health domain. Additionally, the self-assessment of general health in men was significantly positively correlated with cardiopulmonary efficiency. In women, the general health assessment was correlated with upper limb strength and upper body flexibility. Conclusions. It was concluded that after the fifth decade of life, physical fitness plays a greater role in improving the self-assessment of quality of life in women than men. Physical activity undertaken by middle-aged and elderly adults should focus on first improving cardiorespiratory efficiency and then strength and flexibility. Key words: adults 50+, physical fitness, quality of life Introduction Quality of life, according to the World Health Organization, is an individual s perception of his or her position in life in the context of the culture and value system where they live, and in relation to their goals, expectations, standards and concerns. It is a broad ranging concept, incorporating in a complex way a person s physical health, psychological state, level of independence, social relationships, personal beliefs and relationships to silent features in the environment [1, p. 1405]. Among the various aspects that determine quality of life, one important quantifier is independence. Independence, if considered to be a sign of proper functioning in everyday life and done without the help of others, can be associated with maintaining an adequate level of physical fitness. Physical fitness is often congruent to health, itself an important element in determining quality of life [2, 3]. In light of the current phenomenon of population aging, the question arises as to whether the observed increase in life expectancy also involves an increase in fitness levels in old age. In other words, if quality of life decreases with age, then to what extent is this connected with the involutional changes that shape physical fitness in senescence? In Poland, knowledge on the physical fitness of adults and, in particular, the elderly is lacking. Similarly, the literature on the subject is also scant in regards to what * Corresponding author. can be considered as valuable research on the relationships between physical fitness and various aspects of an individual s living environment, which has been suggested to be a very important aspect in this regard [4]. Those studies that were identified focused on the relationship between physical activity and health and quality of life [2, 5 9]. Others discussed the relationships between quality of life and economic status, age, education, martial status, sex, and other factors unrelated to what can be understood as the sphere of physical culture [10 12]. In order to further the understanding of this issue, the aim of this study was to investigate the relationships between the physical fitness levels and self-assessed quality of life in adults and the elderly. Material and methods The research sample included 216 women and 43 men aged 50 to 84 years living in Wrocław, a medium-sized city in Poland. The mean age for women was 65.2 ± 7.6, for men 65.8 ± 8.8 years. A general questionnaire was administered to the participants asking about demographic data, life satisfaction, and overall health. The majority of the participants completed secondary or higher education. In the group of women, 48% completed higher education while 45% finished secondary education. In the group of men, these values were 64% and 29%, respectively. About 7% of the men and 7% of the women only completed primary education or vocational training. In terms of martial status, 51% of the women and 91% of the men were married. 200

11 T. Sławińska, P. Posłuszny, K. Rożek, Physical fitness and quality of life The majority of the sample (92% women, 87% men) declared being in good or rather good health. Those representing the extreme ends of the scale, being in bad and very good health, were 4% and 4% in women and 5% and 8% in men, respectively. Despite the overall high self-reported scores for health, the majority (80%) of the participants declared they had been diagnosed with cardiovascular disease (hypertension, high cholesterol, atherosclerosis) and bone and joint disorders (osteoporosis, osteoarthritis). The vast majority reported that they did not smoke cigarettes or consume alcohol. In the group of women, 88% were non-smokers and 84% abstained from alcohol, in men, 81% of the respondents declared they did not smoke nor consume alcohol. Physical fitness levels were assessed by the Senior Fitness Test, a battery of tests specifically designed for the elderly [13]. This battery is based on the arm curl, chair stand, 6-minute walk, back scratch, chair sit-and-reach, and the 8-foot up-and-go tests. In addition, grip strength of the dominant hand was also measured. Quality of life was scored using the WHOQOL BREF self-assessment questionnaire, an abbreviated generic quality of life scale developed by the World Health Organization [14 16]. It analyzes four life dimensions: physical health (activities of daily living, dependence on medicinal substances and medical aids, energy and fatigue, mobility, pain and discomfort, rest and sleep, work capacity), psychological (bodily image and appearance, negative and positive feelings, self-esteem, spirituality, religion, faith, thinking, learning, memory, concentration), social relationships (personal relationships, social support), and the environment (financial resources, freedom, physical and psychological security, health care, home environment, opportunities for acquiring new information and skills, participation in and opportunities for recreation and leisure, physical environment). Additionally, information was also collected on satisfaction with overall life and health. The results were statistically analyzed, calculating basic descriptive statistics such as arithmetic means ( ) and standard deviations (SD). Stepwise regression analysis was also performed, with the dimensions of quality of life and the assessment on overall quality of life and health treated as the dependent variables while selected results on the physical fitness tests were treated as the independent variables. Tables 2 and 3 present the selected independent variables most strongly correlated with the dependent variables. All calculations were performed using Statistica v. 9.0 software (Statsoft, Poland). Results Table 1 presents the statistical characteristics of the physical fitness tests for the male and female participants. Stepwise regression analysis revealed a larger difference in terms of gender for the number of quality of life di- Table 1. Statistical characteristics of the physical fitness results Men Women Sex Hand grip (kg) Arm curl (n) Chair stand (n) Physical fitness tests 6-minute walk (m) Back scratch (cm) Chair sit-&- reach (cm) 8-foot up-and-go (s) SD SD Factor Table 2. Stepwise regression results for the physical fitness tests that significantly correlated with the quality of life domains and the overall assessment of quality of life and health in men (only significant results presented) Physical Psychological Life domain Social relationships Environment Quality of life Health Hand grip ns ns ns ns ns ns Arm curl ns ns ns ns ns ns Chair stand ns ns ns ns ns ns 6-minute walk ns ns ns ns Back scratch ns ns ns ns ns Chair sit-&-reach ns ns ns ns ns ns 8-foot up-and-go ns ns ns ns ns ns R F P ns ns ns ns non-significant 201

12 T. Sławińska, P. Posłuszny, K. Rożek, Physical fitness and quality of life mensions that were associated with the results on the physical fitness tests (Tab. 2, 3). In the group of men, the only statistically significant relationship found was between aerobic endurance (6-minute walk) and the physical quality of life dimension. The opposite was found in women, where only one of the life dimensions social relationships did not show any correlation with the fitness test results. All three of the remaining quality of life dimensions physical, psychological, and environmental were better assessed by women who registered greater upper limb strength (arm curl test) and lower (chair sit-and-reach test) or upper body (back scratch test) flexibility. Differences between the men and women were also observed in their overall assessment of quality of life and health. For women, their self-assessment on overall quality of life was significantly related to upper limb strength (arm curl test); for men, this was upper body flexibility (back scratch test). For the women s self-assessment of health, the most important factors were upper limb strength (arm curl test) and upper body flexi bility (back scratch test); for men, aerobic endurance (6-minute walk) had the most significant impact. Both assessments were more strongly associated with the selected measures of physical fitness in men than in women. Discussion The components selected in the present study to measure physical fitness are indicative of various human motor skills. It can be assumed that their role in determining self-assessed quality of life can be varied. Grzegorczyk et al. [11] also attempted to analyze the relationship between quality of life and physical fitness in the elderly based on a questionnaire (the Nottingham Health Profile). They claimed that among the measured variables, the greatest impact on the quality of life of the respondents was physical fitness. They reported that, in a group of senior citizens living in nursing homes, the correlation between physical fitness and quality of life was r = 0.75, whereas in a group of seniors attending the University of the Third Age, the correlation coefficient was even higher, at r = These high correlations indicate the important role of physical fitness in self-assessed quality of life. Such a relationship between physical fitness and quality of life in the elderly has also been reported by Wojszel and Bień [17]. However, besides generally confirming that such a relationship exists, what would be more interesting is examining which aspects of physical fitness (motor performance) have the greatest impact on quality of life, but not just quality of life treated as a whole but in terms of the specific dimensions of this rather widely understood concept. For this purpose, a subjective assessment of physical fitness levels is insufficient. Instead, it is necessary to examine its various manifestations using accurate, reliable, objective, and standardized physical fitness tests. These include such instruments as the Senior Fitness Test (otherwise known as the Fullerton Functional Fitness Test) designed specifically for elderly persons. It is intended to assess those elements of physical fitness that are the most essential in performing activities of daily living both independently and safely as well as those that motivate the elderly to improve their efficiency [18]. Therefore, such tests can indirectly aid in both assessing and improving quality of life in the elderly. According to Paffenbarger et al. [19], the results of such tests investigating various aspects of quality of life may also point to their long-term effects. The present study sought to estimate the mutual relationships between selected measures of physical fitness and various aspects of quality of life in a middle-aged and elderly sample. Based on the obtained results, it was found that higher levels of physical fitness better contributed to a higher assessment of quality of life and health in men than in women. Such sex-based differences Table 3. Stepwise regression results for the physical fitness tests that significantly correlated with the quality of life domains and the overall assessment of quality of life and health in women (only significant results presented) Factor Physical Psychological Life domain Social relationships Physical Quality of life Health Hand grip ns ns ns ns ns ns Arm curl ns Chair stand ns ns ns ns ns ns 6-minute walk ns ns ns ns ns ns Back scratch ns ns ns Chair sit-&-reach ns ns ns ns ns 8-foot up-and-go ns ns ns ns ns ns R F P ns ns non-significant 202

13 T. Sławińska, P. Posłuszny, K. Rożek, Physical fitness and quality of life were also demonstrated by Król-Zielińska et al. [20], finding that older-aged men are more susceptible to environmental factors than women. At the same time, more detailed analysis showed that this difference only applied to the physical quality of life dimension, which consisted of, among others, work capacity and performing activities of daily living. In women, both self-assessed health and quality of life as well as the physical, psychological, and environmental quality of life domains were associated with physical fitness. Although these results were not very strong, they were connected to many different aspects in the functioning of women in everyday life. Other studies have indicated a decrease in sex-based differences in the elderly in terms of their energy expenditure, itself connected with the amount of physical activity performed everyday [20]. Such difference between sexes also was found among the selected physical fitness criteria correlating with different quality of life domains and the self-assessment of overall quality of life and health. In men, these were aerobic capacity and upper body flexibility; in women, these were upper limb strength and overall flexibility. A study performed on a similar sample also in a medium-sized city in Poland (although using a different quality-of-life questionnaire) by Osiński et al. [21] indicated a small albeit statistically significant relationship between selected elements of quality of life with the levels of aerobic endurance and upper limb flexibility. At the opposite end of the spectrum, those participants who assessed their quality of life as low were found to more frequently report mobility limitations or feeling fatigued. Low cardiorespiratory efficiency and capacity are connected with the occurrence of cardiovascular disease, which is currently one of the most common ailments affecting the elderly population and a factor worsening quality of life [22]. This relationship between cardiorespiratory efficiency and quality of life was also reported by Fleg et al. [23]. Therefore, improving this parameter should be a priority, especially in view of the fact that 82.1% of elderly Polish seniors in the region where this study was performed declared cardiorespiratory problems, which in turn undoubtedly has a negative effect on their quality of life as well life expectancy [24]. Conclusions After the fifth decade of life, physical fitness plays a greater role in improving the self-assessment of quality of life in women than men. Furthermore, the self-assessment of health is associated with different components of physical fitness. In women, this was found to be primarily connected to upper limb strength; in men, this was aerobic endurance. As a result, physical activity among the middle-aged and elderly should focus first on improving cardiorespiratory capacity and then strength and flexibility. Acknowledgments This study was supported by the Ministry of Science and Higher Education (grant No ). References 1. The WHOQOL Group, The World Health Organisation quality of life assessment (WHOQOL): Position paper from the World Health Organisation. Soc Sci Med, 1995, 41 (10), , doi: / (95)00112-K. 2. Drewnowski A., Evans W.J., Nutrition, physical activity, and quality of life in older adults: summary. J Gerontol A Biol Sci Med Sci, 2001, 56 (Suppl. 2), 89 94, doi: / gerona/56.suppl_ Nelson M.E., Rejeski W.J., Blair S.N., Duncan P.W., Judge J.O., King A.C. et al., Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc, 2007, 39 (8), , doi: /mss.0b013e aa2. 4. Iwanowicz E., Health promotion for elderly people [in Polish]. Annales Universitatis Mariae Curie-Skłodowska, Lublin Polonia, Sectio D, 2005, LX (150, Suppl. XVI), Bronikowska M., Bronikowski M., Scott N., You think you are too old to play? Playing games and aging. Hum Mov, 2011, 12 (1), 24 30, doi: /v Fox K.R., The influence of physical activity on mental well-being. Public Health Nutr, 1999, 2 (Suppl. 3a), , doi: /S Kerse N.M., Flicker L., Jolley D., Arroll B., Young D., Improving the health behaviours of elderly people: randomised controlled trial of a general practice education programme. BMJ, 1999, 319, , doi: /bmj Spirduso W.W, Cronin D.L., Exercise dose-response effects on quality of life and independent living in older adults. Med Sci Sports Exerc, 2001, 33 (Suppl. 6), S598 S Stachoń A., Burdukiewicz A., Pietraszewska J., Andrzejewska J., Chromik K., Biological symptoms of aging in women regarding physical activity and lifestyle. Hum Mov, 2010, 11 (2), , doi: /v Głębocka A., Szarzyńska M., Social support and well-being among the elderly [in Polish]. Gerontologia Polska, 2005, 13 (4), Grzegorczyk J., Kwolek A., Bazarnik K., Szeliga E., Wolan A., Quality of life of nursing home residents and senior mature students [in Polish]. Przegląd Medyczny Uniwersytetu Rzeszowskiego, 2007, 3, Knurowski T., Lazić D., Van Dijk J.P., Madarasova Geckova A., Tobiasz-Adamczyk B., van den Heuvel W.J.A., Survey of Health Status and Quality of Life of the Elderly in Poland and Croatia. Croat Med J, 2004, 45 (6), Jones J., Rikli R., Measuring functional fitness of older adults. J Active Aging, 2002, March-April, O Carroll R.E. 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14 T. Sławińska, P. Posłuszny, K. Rożek, Physical fitness and quality of life 16. Skevington SM., O Connell K.A., Can we identify the poorest quality of life? Assessing the importance of quality of life using the WHOQOL-100. Qual Life Res, 2004, 13 (1), 23 34, doi: /B:QURE be. 17. Wojszel B., Bien B., Health and fitness of the population of people in advanced old age in a big city and rural environments [in Polish]. In: Charzewski J. (red.), Aging Problems, Fourth Anthropological Workshop. AWF, Warszawa 2001, Osiński W., Physical activity undertaken by elderly [in Polish]. Antropomotoryka, 2002, 24, Paffenbarger R.S.Jr., Hyde R.T., Wing A.L., Lee J.M., Kampert J.B., Some interrelations of physical activity, physiological fitness, health and longevity. In: Bouchard C., Shepard R.J., Stephens T. (ed.), Physical Activity, fitness, health. Human Kinetics Books, Champaign 1994, Król-Zielińska M., Zieliński J., Kusy K., Physical activity of women and men after 60 years of age [in Polish]. Universitatis Mariae Curie-Skłodowska, Lublin Polonia, Sectio D Medicina, 2005, LX (3, Suppl. XVI), Osiński W. (ed.), Impact of aging on physical activity, fitness and health. AWF, Poznań Muszalik M., Kędziora-Kornatowska K., Quality of life of chronically ill elderly [in Polish]. Gerontologia Polska, 2006, 14 (4), Fleg J.L., Morrell C.H., Bos A.G., Brant L.J., Talbot L.A., Wright J.G. et al., Accelerated longitudinal decline of aerobic capacity in healthy older adults. Circulation, 2005, 112 (5), , doi: / CIRCULATIONAH Bogowolska-Wepsięć M., Dąbrowska G., Klakočar J., Machaj Z., Pierzchalska A., Pisarczyk-Bogacka E. et al., Living condition of seniors in Lower Silesia. The Study Report. Part II. Analysis of study results [in Polish]. Urząd Marszałkowski Województwa Dolnośląskiego, Wrocław Available from: Paper received by the Editor: October 18, 2011 Paper accepted for publication: July 11, 2013 Correspondence address Teresa Sławińska Zakład Antropokinetyki Akademia Wychowania Fizycznego al. I.J. Paderewskiego Wrocław, Poland sloter@awf.wroc.pl 204

15 2013, vol. 14 (3), Body composition in male physical education university students in view of their physical activity level doi: /humo Aleksandra Stachoń *, Jadwiga Pietraszewska University School of Physical Education, Wrocław, Poland Abstract Purpose. Body composition and fat distribution is specific for particular populations and social groups. However, one factor that significantly affects body composition is physical activity. The aim of the study was to assess the various components of body composition in male physical education students with regard to their physical activity level. Methods. A detailed questionnaire survey on physical activity was administered to 252 male students. Based on their responses, the participants were placed into two groups engaged in either moderate or vigorous physical activity. Anthropometric measurements included measures of body height and mass and also skinfold thickness. Body composition was assessed by bioelectrical impedance analysis. Statistical analysis was performed by comparing the groups mean values, standard deviations, and percentages of the components of body composition. Results. The groups did not differ significantly for mean body height and mass. No statistically significant differences were found in the absolute amounts of the various components of body composition (except for fat mass) between the groups. Both groups had 61.5 kg of fat-free mass (constituting 80.6% of body mass for the vigorously active and 78.7% of body mass for the moderately active students) and both had 44 kg of muscle mass (constituting 58.3% and 56.1% of body mass, respectively). Students who declared to be involved in vigorous physical activity had 2 kg less and 2% lower fat mass than those involved in moderate physical activity (based on BIA measurements). Measures of skinfold thickness found more subcutaneous fat tissue in the vigorously active group, but the use of a fat index based on body height found them to present less fat. Conclusions. The difference in fat content between physical education students who were more or less physically active was found to be 2 kg and 2%. The results found that physical activity level was not associated with body height, body mass, and the absolute amounts of the other studied components of body composition. Key words: body components, BIA method, skinfolds, BMI, fatness, moderate and vigorous activity Introduction The effects of increased physical activity include changes in body composition [1 4]. The scale of observed changes depends on the type of physical activity or sport one is engaged in as well as the individual features and predispositions of that individual. These include sex, age, somatotype, and the specific dynamics of one s metabolic processes. Physical education university students with regard to the specific character of their studies are expected to feature different body composition when compared with the general population. However, recent changes in higher education dynamics including the enrollment structure and overall education system may have influenced the size of these differences. The most accurate methods of measuring body composition include magnetic resonance imaging and computed tomography [5]. Unfortunately, these methods are expensive and mainly applied in medical diagnostic fields their wide application in population-based studies is difficult to justify. However, the use of bioelectrical impedance analysis (BIA) is gaining popularity as a relatively simple and non-invasive method for the indirect estimate of total body water, body fat, and muscle mass. Due to its confirmed high repeatability, BIA has been widely used in population studies as well as in replicating research [6 7] to allow a comparative analysis of the results of studies on different populations. BIA determines the resistance and reactance of body tissues to the flow of an electric current, which is of low charge (< 1 ma), imperceptible to the subject, and at a frequency of at least 50 khz. A more precise description of BIA and its methodology can be found in Kyle et al. [8] and Lewitt et al. [9]. The aim of the present study was to examine body composition with BIA in a group of male university students studying physical education with regard to their physical activity level. In addition, measurements of subcutaneous fat were performed. The study intended to identify those components of body composition that could differentiate those who declared being involved in vigorous physical activity and those in moderate physical activity. The presented study is part of longitudinal survey attempting to detect secular trends in the body tissue composition and somatotypes of students attending the University School of Physical Education in Wrocław, Poland [10]. * Corresponding author. 205

16 A. Stachoń, J. Pietraszewska, Body composition and physical activity Material and methods The study material consisted of cross-sectional anthropometric measurements, an assessment of body composition, and responses to a questionnaire survey. The population sample consisted of 252 male students aged years attending the University School of Physical Education in Wrocław, Poland, during the academic year. All were studying either Physical Education or Physiotherapy. The participants mean age was 20.9 ± 2.0 years, mean body height ± 6.7 cm, and body mass 77.3 ± 10.8 kg. Body height was measured to the nearest 0.1 cm using the methodology outlined by Martin and Saller [11] with the use of a GPM anthropometer (Siber Hegner Machinery Ltd., UK). Body fat was measured by skinfold thickness (subscapular, triceps, forearm, suprailiac, abdominal, and calf) with a Tanner/Whitehouse skinfold caliper (Holtain, UK) with 0.2 mm graduation. Body mass was measured with an electronic weighing scale with an accuracy of 0.1 kg. The anthropometric measurements were then used to calculate a Subcutaneous Fat Index (SFI), an index proposed by the present authors that takes into account trunk and extremity skinfolds and body height. It was believed that the SFI would provide a more unambiguous form of reporting for later interpretation than the other popular indexes currently used for evaluating body fat. sssf + tsf + fsf + asf + sisf + csf (mm) SFI = 100 body height (cm) sssf subscapular skinfold, tsf triceps skinfold, fsf forearm skinfold, sisf suprailiac skinfold, asf abdomen skinfold, csf calf skinfold The participants body build was also determined by calculating the Body Mass Index (BMI) following the World Health Organization s (WHO) guidelines. Measurements of body composition by bioelectrical impedance analysis (BIA) were performed with a BIA-101 Anniversary Sport Edition analyzer (Akern, Italy) in standard conditions (in the supine position on an empty stomach). Analysis of tissues was performed with Bodygram software packaged with the Akern analyzer. The percentages of the following components of body composition were measured: fat mass (FM), fat-free mass (FFM), total body water (TBW), extracellular water (ECW), intracellular water (ICW), muscle mass (MM), body cell mass (BCM). The students were administered a self-tailored detailed survey regarding the regularity, frequency, and types of physical exercise/physical activity they performed. Following WHO guidelines [12], this included all leisure activities and physical activity performed during curricular activities. The reliability and repeatability of the questionnaire was previously demonstrated in unpublished works. Based on their responses, the sample was divided into two groups depending on physical activity level: those who performed moderate activity (irregular walks, jogging, swimming, etc., n = 85) or vigorous activity (regular physical exercise or training more than twice a week, n = 167). Statistical analysis included calculating the arithmetic means and standard deviations of the anthropometric measurements. The Shapiro-Wilk test was used to check the distribution of the examined variables for normal distribution. Levene s test was applied to assess the equality of variances of both groups (moderate and vigorous activity). The significance of differences was checked with Student s t test, and the differences between the percentages of the analyzed body components were checked with the Two-Proportion z Test. The level of statistical significance was set at p = All statistical calculations were performed with Statistica 9.0. software (Statsoft, USA), whereas Office Excel 2003 (Microsoft, USA) was used to create graphical representations of the data. The study was approved by the Ethics Committee of the University School of Physical Education in Wrocław, Poland and written informed consent was obtained from all participants. Results No statistically significant differences were found for body height (Student s t = 0.81; p = ) or body mass (Student s t = 1.66; p = ) between the students engaged in moderate and vigorous physical activity. However, it should be noted that the more physically active participants had slightly lower body mass than the less active ones (76.5 kg vs kg, respectively). The results of body composition analysis are summarized in Table 1 and Figure 1. Those students declaring higher levels of physical activity did not differ significantly for fat-free mass from their less physically active counterparts, although the percent of fat-free mass was 2% greater for students engaged in vigorous physical activity. The two groups differed significantly in the absolute amount of fat mass. The students engaged in vigorous physical activity had 2 kg and 2% less fat mass than those engaged in moderate physical activity. The more physically active students featured 2% greater muscle mass than their less active counterparts, but the difference was not significant in either the absolute or relative amount of muscle mass between the two groups. The more physically active students also featured better hydration values than the other group. Differences in the range of % were found for total body water, extracellular water, and intracellular water content. Although no statistically significant differences were observed in the absolute amount of total body water, the more physically active students had less extracellular water and more 206

17 A. Stachoń, J. Pietraszewska, Body composition and physical activity Table 1. Means and standard deviations of the components of body composition (in kg) estimated by BIA, including Student s t test p values Body components (kg) vigorous activity n = 167 M ± SD moderate activity n = 82 Student s t test p FFM 61.5 ± ± FM 15.0 ± ± MM 44.5 ± ± TBW 45.0 ± ± ECW 18.1 ± ± ICW 26.9 ± ± BCM 36.8 ± ± FFM fat-free mass, FM fat mass, MM muscle mass, TBW total body water, ECW extracellular water, ICW intracellular water, BCM body cell mass; statistically significant differences marked in bold Table 2. Means and standard deviations (in mm) of skinfold thickness measurements, including Student s t test p values Skinfold (mm) vigorous activity n = 167 M ± SD moderate activity n = 82 Student s t test p Subscapular 9.5 ± ± Triceps 5.5 ± ± Forearm 3.8 ± ± Suprailiac 9.0 ± ± Abdominal 10.0 ± ± Calf 5.6 ± ± Table 3. Means and standard deviations of BMI and SFI, including Student s t test p values Index BMI (kg/m 2 ) Subcutaneous Fat Index (SFI) vigorous activity n = (2.5) 28.4 (16.0) M ± SD moderate activity n = (2.9) 30.7 (17.3) Student s t test p intracellular water than the students engaged in moderate activity. The former also had a clearly higher percentage of body cell mass but only a slightly higher absolute amount of this component. The results of the Two-Proportion z Test did not indicate any statistical significance of the observed differences in the relative amounts of the components of body composition. The two groups did not differ significantly for mean subscapular, triceps, forearm, suprailiac, abdominal, and calf skinfold thickness (Tab. 2). It must be noted, PERCENTAGES OF BODY MASS [%] ,6 78,7 19,4 FFM fat-free mass, FM fat mass, MM muscle mass, TBW total body water, ECW extracellular water (% of TBW), ICW intracellular water (% of TBW), and BCM body cell mass; differences in percent body composition of the particular components were found to be not statistically significant with p values of in the Two-Proportion z Test Figure 1. Body composition estimated by BIA as a percentage of body mass however, that the more active students had slightly thicker skinfolds (differences ranging from 0.5 to 1.0 mm). However, the Subcutaneous Fat Index (SFI), adopted to measure the ratio of subcutaneous fat to body height, revealed lower body fat for those students engaged in vigorous physical activity (Tab. 3). The mean BMI values for both groups showed that the more active students could be characterized as having a more slender body than the students involved in moderate physical activity; however, this difference was also not statistically significant (Tab. 3). Discussion 21,3 58,3 56,1 59,0 FFM FM MM TBW ECW ICW BCM The effects of vigorous physical activity on the reduction of body fat as well as the fact that physically active students generally have lower adiposity levels have been well-documented [13 15]. Researchers have studied this issue in studies on various populations and age groups [2, 16 17]. The present study found that the difference in body fat content between the two groups of male physical education students engaged in different physical activity levels was 2 kg and 2%. A previous study by Pietraszewska et al. [18] revealed a 3% difference in fat mass between more (19.3%) and less (22.5%) physically active students from the same region. Furthermore, the percentage of body fat (19.4%) found for the students engaged in vigorous physical activity in this study is consistent with the results of Pietraszewski et al. [19], who noted 19.6% body fat using the same type of body composition analyzer also on a group of physical education students from the same region of Poland. However, according to a recent study performed at the University of Physical Education in Warsaw, Poland, this group of physical education students regardless of their level of physical activity had about 12% fat mass [20], which is less than the students from the present study. This inconsistency may stem from using different methods of analyzing body composition. Swartz et al. [21] noted 57,6 40,3 41,3 BODY TISSUE COMPONENTS VIGOROUS ACTIVITY MODERATE ACTIVITY 59,7 58,7 59,8 58,7 207

18 A. Stachoń, J. Pietraszewska, Body composition and physical activity that less active students, i.e., those performing fewer than 2.5 hours of aerobic activity per week had 4% (measured by hydrostatic weighing) or 1.5% (by BIA) more body fat than vigorously active students. A similar result was found between more or less physically active female physical education students, with a 2% difference found in measures of fat content [22]. No significant differences were observed in the thickness of skinfolds between the participants engaged in vigorous physical activity and those in moderate activity. Pietraszewska et al. [18] found that more physically active students presented thinner triceps and suprailiac skinfolds. It seems that more active students examined in the present study had slightly more absolute subcutaneous fat, although most skinfolds were thicker by only about 0.5 mm than those who were less active. Trunk skinfold thickness was about half of that measured on the extremities. The values calculated using the Subcutaneous Fat Index showed that subcutaneous fat in relation to body height was lower in the more physically active students than those less active. This was also confirmed by the lower mean BMI scores, lower body mass, and more slender body build for the more active students than the less active individuals. Previous studies also revealed a reduction in skinfold thickness in men and women after several weeks of physical training [23]. The relationship between skinfold thickness and body mass and height has been well-documented [24], finding that the volume of subcutaneous fat depends on body size and its potential to be reduced is limited. The results also found that the two groups differed from each other in terms of body composition as a percentage of each individual component. The more active students had 2% greater muscle mass as well as body cell mass and intracellular water content than their less active counterparts. Interestingly, Convertino [25] reported an increase in body fluids after training, while Pickering, Fellmann, and Morio [26] did not find any changes in total body water in a group of older students after several weeks of training, observing only a decrease in fat mass. The students in the present study were found with a generally low level of hydration (about 58%). The more physically active students also had less extracellular water and more intracellular water than the students performing physical activity at a moderate level. Similar hydration values were also observed by Pietraszewski et al. [19], finding more active students to be charac terized by higher hydration levels (TBW = 59.1%) compared with less active students (TBW = 56.7%) [18]. Nonetheless, it needs emphasis that the differences in body composition as a percentage of each component observed in the present study were not statistically significant. This finding may be due to the small size of the study groups and the constraints of using the Two-Proportion z Test. Conclusions Male students studying physical education who declared to be involved in vigorous of physical activity were found to have 2 kg and 2% less fat mass than those engaged in moderate levels of physical activity. A higher level of physical activity was correlated with a higher percentage of fat-free mass, muscle mass, body cell mass, total body water, and intracellular water. No differences were found in the thickness of skinfolds between those students involved in moderate and vigorous activity. However, the level of relative subcutaneous fat (in relation to body height) was smaller in the more active students. References 1. Hagerman F.C., Walsh S.J., Staron R.S., Hikida R.S., Gilders R.M., Murray T.F. et al., Effects of high-intensity resistance training on untrained older men. I. Strength, Cardiovascular, and Metabolic Responses. J Gerontol A Biol Sci Med Sci, 2000, 55 (7), B336 B346, doi: / gerona/55.7.b Schwartz R.S., Shuman W.P., Larson V., Cain K.C., Fellingham G.W., Beard J.C. et al., The effect of intensive endurance exercise training on body fat distribution in young and older men. Metabolism, 1991, 40 (5), , doi: / (91)90239-S. 3. Burdukiewicz A., Pietraszewska J., Andrzejewska J., Witkowski K., Stachoń A., Chromik K. et al., Morphological differentiation and body composition in female judokas and female weightlifters in relation to the performed sport discipline. Arch Budo, 2010, 6 (2), Gremeaux V., Drigny J., Nigam A., Juneau M., Guilbeault V., Latour E. et al., Long-term lifestyle intervention with optimized high-intensity interval training improves body composition, cardiometabolic risk, and exercise parameters in patients with abdominal obesity. Am J Phys Med Rehabil, 2012, 91 (11), , doi: /PHM.0b013e ce0. 5. Ellis K.J., Human Body Composition: In Vivo Methods. Physiol Rev, 2000, 80 (2), Lukaski H.C., Bolonchuk W.W., Hall C.B., Siders W.A., Validation of tetrapolar bioelectrical impedance method to assess human body composition. J Appl Physiol, 1986, 60 (4), Kutáč P., Gajda V., Evaluation of accuracy of the body composition measurements by the BIA method. Hum Mov, 2011, 12 (1), 41 45, doi: /v x. 8. Kyle U.G., Bosaeus I., de Lorenzo A.D., Deurenberg P., Elia M., Gómez J.M. et al., Bioelectrical impedance analysis part I: review of principles and methods. Clin Nutr, 2004, 23 (5), , doi: /j.clnu Lewitt A., Mądro E., Krupienicz A., Theoretical foundations and practical applications of bioelectrical impedance analysis (BIA) [in Polish]. Endokrynologia, Otyłość, Zaburzenia Przemiany Materii, 2007, 3 (4), Stachoń A., Burdukiewicz A., Pietraszewska J., Andrzejewska J., Changes in body build of AWF students Can a secular trend be observed? Hum Mov, 2012, 13 (2), , doi: /v

19 A. Stachoń, J. Pietraszewska, Body composition and physical activity 11. Martin R., Saller K., Handbook of Anthropology. Part 1 [in German]. Gustav Fischer, Stuttgart World Health Organization, Intensity of physical activity. Available from: URL: [Accessed: ). 13. Tremblay A., Després J.P., Leblanc C., Craig C.L., Ferris B., Stephens T. et al., Effect of intensity of physical activity on body fatness and fat distribution. Am J Clin Nutr, 1990, 51 (2), Gutin B., Barbeau P., Owens S., Lemmon C.R., Bauman M., Allison J. et al., Effects of exercise intensity on cardiovascular fitness, total body composition, and visceral adiposity of obese adolescents. Am J Clin Nutr, 2002, 75 (5), Slentz C.A., Duscha B.D., Johnson J.L., Ketchum K., Aiken L.B., Samsa G.P. et al., Effects of the amount of exercise on body weight, body composition, and measures of central obesity. STRRIDE A randomized controlled study. Arch Intern Med, 2004, 164 (1), 31 39, doi: / archinte Obarzanek E., Schreiber G.B., Crawford P.B., Goldman S.R., Barrier P.M., Frederick M.M. et al., Energy intake and physical activity in relation to indexes of body fat: the National Heart, Lung, and Blood Institute Growth and Health Study. Am J Clin Nutr, 1994, 60 (1), Hughes V.A., Frontera W.R., Roubenoff R., Evans W.J, Fiatarone Singh M.A., Longitudinal changes in body composition in older men and women: role of body weight change and physical activity. Am J Clin Nutr, 2002, 76 (2), Pietraszewska J., Burdukiewicz A., Miałkowska J., Andrzejewska J., The characteristics of a somatic structure and body composition from an aspect of student physical activity In: Rutkowska E. (ed.), Sport vs. wellness. NeuroCentrum, Lublin Pietraszewski B., Pietraszewska J., Burdukiewicz A., Relationship between knee joint flexor and extensor torques and tissue components in young men. Hum Mov, 2009, 10 (1), 21 25, doi: /v Smolarczyk M., Wiśniewski A., Czajkowska A., Kęska A., Tkaczyk J., Milde K. et al., The physique and body composition of students studying physical education: a preliminary report. Pediatr Endocrinol Diabetes Metab, 2012, 18 (1), Swartz A.M., Evans M.J., King G.A., Thompson D.L., Evaluation of a foot-to-foot bioelectrical impedance analyser in highly active, moderately active and less active young men. Br J Nutr, 2002, 88 (2), , doi: / BJN Stachoń A., Pietraszewska J, Burdukiewicz A., Andrzejewska J., Effect of physical activity in young women [in Polish]. Medycyna Ogólna i Nauki o Zdrowiu, 2013, 19 (2), Norton K., Olds T. (eds.), Anthropometrica: A textbook of body measurement for sports and health Ccurses. UNSW Press, Sydney 2002, Friedl K.E., Westphal K.A., Marchitelli L.J., Patton J.F., Chumlea W.C., Guo S.S., Evaluation of anthropometric equations to assess body-composition changes in young women, Am J Clin Nutr, 2001, 73 (2), Convertino V.A., Blood volume: its adaptation to endurance training. Med Sci Sports Exerc, 1991, 23 (12), Pickering G.P., Fellmann N., Morio B., Ritz P., Amonchot A., Vermorel M. et al., Effects of endurance training on the cardiovascular system and water compartments in elderly subjects. J Appl Physiol, 1997, 83 (4), Paper received by the Editors: March 20, 2013 Paper accepted for publication: August 22, 2013 Correspondence address Aleksandra Stachoń Zakład Antropologii Fizycznej Akademia Wychowania Fizycznego al. I.J.Paderewskiego Wrocław, Poland aleksandra.stachon@awf.wroc.pl 209

20 2013, vol. 14 (3), Physical activity and life satisfaction in blind and visually impaired individuals doi: /humo Jakub Łabudzki 1, 2, Tomasz Tasiemski 1 * 1 University School of Physical Education, Poznań, Poland 2 Osteo-Reh Physiotherpay Clinic, Pniewy, Poland Abstract Purpose. Physical activity (PA) is known to have a positive influence on many physical and psychological aspects of human life. Despite the many benefits of an active lifestyle, the majority of adults in Western Europe do not perform regular PA, and this is especially so for adults with a disability, such as the blind and visually impaired. The purpose of this study was to assess the type and intensity of physical activity and subjective quality of life (life satisfaction) of blind and visually impaired individuals living in Poland and to analyze for potential differences in terms of their physical activity levels. Method. The short form International Physical Activity Questionnaire and the Life Satisfaction Questionnaire were administered to a sample of eighty-two individuals (mean age 38 years) with varying degrees of vision loss. Results. The study found that more than 50% of the respondents were classified as being highly active and that the total sample was rather satisfied with life as a whole. The level of PA performed was significantly positively correlated with the level of life satisfaction. Conclusions. PA increases the subjective quality of life in blind and visually impaired individuals. Key words: physical activity, life satisfaction, quality of life, blind, visually impaired Introduction Physical activity (PA) is closely connected to mental health and the feeling of well-being [1]. Studies carried out in the European Union have found that the amount of physical activity performed (at vigorous, moderate, or walking levels of intensity) is highly varied among EU countries. For example, a study on eight EU countries found that the highest level of PA was recorded in Germany while the lowest in Italy [2]. Despite the many benefits of an active lifestyle, the majority of adults in Western Europe do not perform regular PA [3]. This is doubly so for individuals with a visual impairment, who are even less likely to participate in PA than the rest of the population [4, 5]. However, similar research on the blind and visually impaired in Eastern Europe, especially in Poland, could not be found. Insufficient PA exposes adults who are blind and visually impaired to more health risks than sighted people. Ray [5] linked low levels of PA as an indirect cause of increased risk of stroke, osteoporosis, depression, hypertension, heart disease, diabetes, and falls in the blind. The difficulty the visually impaired have with performing motor tasks that require strength and speed, typical components of PA, places them at higher risk of chronic illnesses. Although reduced levels of PA are the result of less independence after experiencing vision loss, the inability to perform certain activities is not treated as * Corresponding author. a factor lowering the quality of life by the visually impaired [5]. For example, Hollbrook [4] found a higher quality of life among individuals with the most severe form of visual impairment compared with those with less impaired sight. However, one of the major problems of assessing the quality of life of individuals who are blind and visually impaired is the presence of coexisting illnesses and diseases [4, 6]. Research on visually impaired individuals presenting no diseases or complications (aged years) found that most did not declare any encumbered difficulties with the ability to function independently or when performing activities of daily living [6]. However, research has shown that the quality of life of visually impaired women is lower than that of men with a similar loss of visual function [4, 6]. Furthermore, individuals who experienced vision loss before twelve years of age reported greater anxiety or depression than those who lost their sight later in life. A relationship was also found between a sedentary lifestyle and decreased life satisfaction among the blind and visually impaired [5]. A Dutch study demonstrated that individuals with vision impairment had a lower quality of life than healthy controls, although higher than patients after a stroke or with post-viral fatigue syndrome [6]. This study also found that the blind and visually impaired group, when compared with individuals suffering from various types of chronic illnesses, ranked themselves in the middle for such aspects as mobility, activities of daily living, anxiety, and depression [6]. However, vision loss has undeniably a greater impact on quality of life than type II diabetes, acute coronary syndrome, 210

21 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals or hearing impairments, although it is considered to be less debilitating than a brain stroke, multiple sclerosis, post-viral fatigue syndrome, or mental disorders [6]. Studies on the life satisfaction of individuals with disabilities in Poland, and not just those with vision impairment, are rare. The available literature on the subject finds research conducted on only five different groups of individuals with a disability, all using the same research tool developed by Fugl-Meyer et al. [7]. The highest level of satisfaction with life was declared by women after mastectomy [8], followed by individuals with multiple sclerosis (MS) [9], those with rheumatoid arthritis (RA) [10], individuals with a spinal cord injury (SCI) [11], and those who suffered a stroke [12]. Consistent results were noted across all of the above studies, with disabled Polish individuals declaring family life and friendship as the most satisfactory, while rating their professional and financial situation as the least satisfactory [8 12]. However, no mention or reference was found to the level of satisfaction with life of Poles who are blind and visually impaired. The lack of domestic research on the level of PA and life satisfaction of individuals with a visual impairment were the main motivational factors for the developing the present study. The purpose was to assess the PA levels and subjective quality of life (life satisfaction) of blind and visually impaired individuals living in Poland and search for potential differences in terms of their (daily) physical activity level (PAL). It was expected that those with high levels of PA in this sample would be more satisfied with their lives than those characterized by low PA. Material and methods Participants for the study were recruited with the help of the Polish Association of the Blind as well as by peer referral. Invitations to take part in the study were sent by . Individuals who agreed to participate had the following inclusion criteria: to be medically diagnosed as visually impaired (significant, moderate, or light impairment) and at least 18 years of age. This resulted in a sample of 82 blind and sight impaired individuals (39 women and 43 men, mean age 38 ± 12.1 years; 79% declared to have significant visual impairment). The participants were asked to complete a three-part online questionnaire on their computer using screen reader software. They were first asked to complete a personal questionnaire, which contained seven questions on demographic data such as gender, data of birth, marital status, current place of residence, address, education, and employment history (see Tab. 1). An additional question was included asking when vision loss was experienced and its severity. The other two electronic questionnaires consisted of the following research instruments: 1) International Physical Activity Questionnaire (IPAQ) Polish version [13], a short form version Table 1. Demographic data of the participants Demographic Sample (N = 82) n (%) Education* Elementary 2 (2.4) Vocational 5 (6.1) Secondary 23 (28.0) Professional schooling 11 (13.4) Bachelor s degree 3 (3.7) Master s degree 36 (43.9) Place of residence City 33 (40.2) Village 6 (7.3) Capital of a province 43 (52.4) Marital status Single 32 (39.0) Married 29 (35.4) Divorced 8 (9.8) Widow/widower 2 (2.4) Non-marital relationship 11 (13.4) Occupation* Student 8 (9.8) Employed 54 (65.9) Homemaker 9 (11.0) Unemployed 9 (11.0) * missing data (n = 2) of the original IPAQ that contains seven questions on the types of PA an individual performs in an average day. It measures PA in terms of its duration and intensity. All PA (lasting at least 10 minutes) that is performed during work, at or around the home, when commuting, and for leisure as a form of recreation is taken into consideration. Information is also collected on the intensity at which PA is performed, such as the time spent sitting, walking, and performing PA at vigorous and moderate intensities. This allows total daily energy expenditure to be estimated by using the Metabolic Equivalent of Task (MET), i.e., the energy cost of an activity expressed as the ratio of its metabolic rate to 1 MET, or the amount of oxygen consumed at rest (resting metabolic rate, about 3.5 ml 0 2 /1 kg body mass/min). Energy expenditure for different types of PA, according to the IPAQ, is: walking = 3.3 MET, moderateintensity activity = 4.0 MET, and vigorous-intensity activity = 8.0 MET. This allowed the participants to be classified into one of three PA levels. Highly active individuals were those who met one of two criteria: (1) three or more days performing vigorous-intensity activity with a total MET value of at least 1500 MET/week, (2) seven or more days of any combination of PA (walking, moderate or 211

22 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals vigorous PA) exceeding 3000 MET/week. Minimally active individuals were those who met one of three criteria: (1) three or more days of vigorous PA of at least 20 minutes per day, (2) five or more days of moderate-intensity activity or walking at least 30 minutes per day, (3) five or more days of any combination of activity (walking, moderate or vigorous PA) exceeding 600 MET/week. Insufficiently active individuals were treated as those who did not perform any PA or did not meet the criteria for either of the two above categories. The IPAQ has been verified as a reliable and accurate instrument and has been used to study able-bodied populations in various countries [2, 14 16], including Poland [17]. 2) Life Satisfaction Questionnaire (LiSat-9) [7], an instrument used to measure satisfaction as a whole and in eight different life domains, being: self-care ability, leisure situation, vocational situation, financial situation, sexual life, partnership relations, family life, and contacts with friends. Each item is scored on a six-point scale, from 1 (very dissatisfied) to 6 (very satisfied). The recommendation to score the total score (Life Satisfaction Index) as the mean of all eight domains of life, excluding the scale measuring satisfaction with life as a whole, was followed [18], where satisfaction with life as a whole has been positively correlated with the eight life satisfaction domains. Concerning the LiSat-9 s reliability and validity, it has been extensively used in general population studies as well as on individuals with a disability, such as those with MS, RA, SCI, or after a stroke or mastectomy [7 12], with Cronbach s alpha from 0.74 to 0.83 [8 10, 12]. Basic descriptive statistics were used to analyze the data included calculating frequency (N), percent (%), arithmetic mean ( ), standard deviation (SD), and minimum (Min) and maximum (Max) values. Differences in terms of sex were calculated using the Chi-squared test. Due to the normal distribution of the Life Satisfaction Index, analysis on the differences in PAL was performed with univariate analysis of variance (ANOVA) and the Bonferroni correction. All statistical analysis was performed using SPSS ver software (IBM, USA). Results The amount of PA the blind and visually impaired participants performed per week (broken down in terms of intensity: walking, moderate intensity, and vigorous intensity) is presented in Table 2. The mean amount of PA performed, in MET/week, for each intensity, was: vigorous-intensity activity ( = ± ), moderate-intensity activity ( = ± ), and walking ( = ± ), with mean weekly energy expenditure for all participants to be Table 2. Amount and type of physical activity performed by the participants Type of physical activity Days/week (mean) Minutes/ week (mean) MET/week (mean) Vigorous Moderate Walking Table 3. Differences in the physical activity levels based on sex Physical activity level Women (n = 39) Men (n = 43) Total n (%) n (%) n (%) Highly active 21 (53.8) 21 (48.8) 42 (51.2) Minimally active 10 (25.6) 13 (30.2) 23 (28.0) Inactive 8 (20.5) 9 (20.9) 17 (20.7) LiSat-9 Table 4. Mean results for life satisfaction in the different domains of life M ± SD Life as a whole 4.33 ± 1.08 Self-care ability 5.42 ± 0.77 Leisure situation 4.13 ± 1.16 Vocational situation 3.89 ± 1.44 Financial situation 3.70 ± 1.26 Sexual life 3.80 ± 1.64 Partnership relations 4.13 ± 1.73 Family life 4.27 ± 1.27 Contacts with friends 4.44 ± 1.12 Life Satisfaction Index 4.23 ± 0.82 ± In order to better illustrate the PA performed by the participants, the mean number of days per week as well as the mean number of minutes per week spent on PA at each intensity was calculated, finding that the largest amount of days ( = 5.75) and minutes ( = ) per week were spent on walking (Tab. 2). Based on the amount and type of PA performed, it was found that the majority of the participants were classified as highly active individuals (Tab. 3). No significant differences were noted in PA in relation to sex (Chi-square = 0.256, p = 0.88). In terms of happiness, the blind and visually impaired participants self-reported their life satisfaction (as a whole) somewhere between (4) and (5) or rather satisfied and satisfied, respectively (Tab. 4). They also scored other domains of life similarly, such as leisure situation, partnership relations, family life, and contacts with friends. The participants reported they were the most satisfied with their self-care ability, scoring between (5) and (6) or satisfied and very satisfied, 212

23 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals Table 5. Differences in life satisfaction depending on physical activity level Physical activity level LiSat-9 Highly active (n = 42) Minimally active (n = 23) M ± SD Inactive (n = 17) ANOVA (F) Significance (p) Self-care ability 5.54 ± ± ± Leisure situation 4.55 ± ± ± Vocational situation 4.08 ± ± ± Financial situation 3.76 ± ± ± Sexual life 3.80 ± ± ± Partnership relations 4.35 ± ± ± Family life 4.52 ± ± ± Contacts with friends 4.67 ± ± ± Life Satisfaction Index 4.41 ± ± ± respectively. The least satisfaction was felt with their financial situation. The highest life satisfaction was declared by those who were grouped as being highly active (Life Satisfaction Index = 4.40). In the case of those who were physically inactive (the lowest PA level) had a Life Satisfaction Index of 3.79 (Tab. 5). Differences in the Life Satisfaction Index of the blind and visually impaired participants based on their PAL were statistically significant (F (2, 79) = 3.55; p 0.05). Those with high PAL had significantly higher life satisfaction than those with insufficient PAL (inactive). No statistically significant differences were noted in the life satisfaction of participants with minimal PAL and those who were inactive. In relation to satisfaction in the individual life domains, significant differences were found for leisure situation (F (2, 77) = 6.79; p 0.01) and vocational situation (F (2, 73) = 3.67; p 0.05) and PAL. Those who were highly active had significantly higher life satisfaction in leisure situation than those who were inactive. For vocational situation, the participants who were highly active or featured minimal PAL were significantly more satisfied with this life domain than those who were inactive. Discussion The main objective of the present study was to assess the PAL and life satisfaction in a blind/visually impaired Polish sample and examine the relationships between these variables. Surprisingly, it was found that 51.2% of the participants were classified as having high PAL (highly active). For comparison, a study on the population of Poland found that only 33.5% of the respondents declared themselves to be highly active [17]. Paradoxically, one reason for this may be that active blind/visually impaired individuals (66% of the participants were employed; 10% were studying) are forced to engage in more PA precisely because of their disability. Unable to perform such tasks as driving, which is known to contribute to a sedentary lifestyle, this group must walk and use public transportation more often that those who are able-bodied. Another cause for such a large discrepancy may have been the methodology. The population study was conducted in the form of a personal interview, while this study made use an online questionnaire that the respondents completed themselves, which may have exaggerated the presented results [19]. A literature review of the various studies on using the IPAQ to measure PAL found a general recommendation to use this tool in the form of an interview, i.e., such as a telephone poll or a face-to-face survey [15, 19, 20]. The most important problem appears to be clarifying to respondents what are the differences between vigorous- and moderate-intensity PA as well as drawing attention to the fact that such activities as walking need to be performed for 10 minutes without interruption. Average energy expenditure for this group of blind and visually impaired individuals, as measured by the short form IPAQ, was MET over a period of seven days. For comparison, a telephone poll was performed on randomly selected individuals with the same research tool in eight European Union countries, finding average energy expenditure to be MET (Tab. 6) [2]. The results of this study were similar if not in some cases higher than those found in this sample of ablebodied individuals across Europe. For example, the amount of PA performed by this group of blind/visually impaired individuals was similar to the mean PA of the population of Spain ( MET) and higher than that measured in Italy ( MET) and Great Britain ( MET). The number of days of vigorous- and moderate-intensity PA was lower than the mean of most of the studied European Union countries. This was similar in the case of the mean number of minutes of vigorous- and moderate-intensity PA (Tab. 6). However, the number of days spent by this sample walking once per day for at least 10 minutes in a seven-day period (5.75 days) was very 213

24 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals Table 6. Comparison of the amount and type of physical activity performed between the participants of this study and the able-bodied populations of eight EU countries [2] Country Mean MET/ week* Vigorous intensity Moderate intensity Walking Mean MET days/week Mean MET min/week Mean MET days/week Mean MET min/week Mean MET days/week Mean MET min/week Total (n = 4995) Belgium (n = 611) Finland (n = 603) France (n = 599) Germany (n = 653) Italy (n = 600) The Netherlands (n = 606) Spain (n = 600) Great Britain (n = 723) Blind/visually impaired * Mean energy expenditure for a period of seven days for all types of PA Table 7. Comparison of life satisfaction in various life domains among individuals with a disability LiSat-9 Mastectomy [8] MS (n = 30) [9] RA (n = 42) [10] SCI (n = 1034) [11] Stroke (n = 25) [12] Visually impaired (n = 82) Life as a whole Self-care ability Leisure situation Vocational situation Financial situation Sexual life Partnership relations Family life Contacts with friends similar to mean value of all eight EU countries (5.72 days). This result was even more discernible when the amount of time spent walking was calculated as the number of minutes in a week, with the blind/visually impaired group s mean higher by one third than the European norm ( vs minutes, respectively) [2]. This difference may have been caused, as mentioned earlier, by how this group commutes every day. For individuals with a visual disability, walking is considered to be the most accessible form of PA that can be performed without relying on the help of others. The study found that blind and visually impaired Poles rated their life as being rather satisfying (life as a whole = 4.3), which is similar to the overall life satisfaction levels found in women after mastectomy (4.3) and individuals with SM (4.2) [8, 9]. The present group was characterized by a higher level of life satisfaction than those with RA (4.1) or who had suffered a stroke (3.5) [10 12]. All of the above-mentioned studies were also conducted in Poland also used the LiSat-9 scale [8 12]. It was found that the self-care ability, vocational situation, and financial situation domains of the visually impaired were similar to that of other disabled individuals. However, satisfaction with family life was eva luated the lowest by this group when compared with other individuals with a disability (Tab. 7). This study also found differences in the Life Satisfaction Index and satisfaction in the domains of leisure situation and vocational situation with PAL. Generally speaking, those who were highly active were more satisfied in these domains of life than those who were inactive. This may stem from the fact that being more physically active allows individuals to engage in more attractive forms of leisure as well as participate in more rewarding forms of work. The present study did have some limitations that need mentioning, including certain restrictions in choosing the original sample that may have influenced the obtained results. First of all, the study sample was composed of individuals who volunteered to participate in the study by electronic means and had to have access to a computer with an installed screen reader, which may have reduced the study s representativeness. Secondly, the questionnaire was self-reported, which may have 214

25 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals caused some of the responses to be exaggerated due to the natural tendency of wanting to present oneself in the best possible way. As a result, future studies should at least be extended to blind and visually impaired individuals without access to the Internet or a computer and preferably conducted in person. In addition, it would be worthwhile for subsequent research to expand the amount of collected demographic data, such as including information regarding income. This would allow for a direct comparison of an individuals actual financial situation to their declared satisfaction level in this life domain. The subjective assessment of one s financial situation may be in fact quite different from their true financial situation, and this aspect undoubtedly has a role in what types of PA a blind and visually impaired individual can participate in. An additional element that may prove to be very useful in verifying the amount of self-reported PA would be the use of a pe dometer [21, 22], which would allow for a broader comparison of the results with those by other authors. An interesting aspect would be to also compare the everyday PA and life satisfaction of blind and visually impaired individuals who practice intensive sports such as Goalball or tandem cycling [23, 24]. Conclusions 1. More than half of the blind/visually impaired participants were found to be highly active (52.2%). 2. Their subjective rating of their life satisfaction found them to be rather satisfied with life. The highest satisfaction level was reported in the life domains of self-care ability, while the lowest for financial situation and sexual life. 3. Those who were highly active (high PAL score) had significantly higher life satisfaction than those who were inactive (low PAL score). No statistically significant differences were noted in the life satisfaction of participants with minimal PAL or those who were inactive. References 1. Gościńska M., Milde K., Stupnicki R., Physical activity of the subject attending fitness clubs. Papers on Anthropology, 2009, XVIII, Rutten A., Ziemainz H., Schena F., Stahl T., Stiggelbout M., Auweele Y.V. et al., Using different physical activity measurements in eight European countries. Results of the European Physical Activity Surveillance System (EUPASS) time series survey. Public Health Nutr, 2003, 6 (4), , doi: /PHN Spittaels H., Foster C., Oppert J-M., Rutter H., Oja P., Sjöström M. et al., Assessment of environmental correlates of physical activity: development of a European questionnaire. Int J Behav Nutr Physical Activity, 2009, 6, 39, doi: / Holbrook E.A., Caputo J.L., Perry T.L., Fuller D.K., Morgan D.W., Physical activity, body composition, and perceived quality of life of adults with visual impairments. J Visual Impair Blin, 2009, 103 (1), Ray C.T., Horvat M., Williams M., Blasch B.B., Clinical assessment of functional movement in adults with visual impairments. J Visual Impair Blin, 2007, 101 (2), Langelaan M., de Boer M.R., van Nispen R.M.A., Wouters B., Moll A.C., van Rens G.H.M.B., Impact of visual impairment on quality of life: a comparison with quality of life in the general population and with other chronic conditions. Ophthalmic Epidemiol, 2007, 14 (3), , doi: / Fugl-Meyer A.R., Bränholm I-B., Fugl-Meyer K.S., Happiness and domain specific life satisfaction in adult northern Swedes. Clin Rehabil, 1991, 5 (1), 25 33, doi: / Tasiemski T., Kujawa M., Pokaczajło J., Quality of life in women after mastectomy [in Polish]. Fizjoterapia, 2009, 17 (4), Tasiemski T., Koper M., Miler M., Objective quality of life and life satisfaction level of people suffering for multiple sclerosis [in Polish]. Fizjoter Pol, 2011, 3 (4), Tasiemski T., Agniaszwili-Biedna N., Wilski M., Objective and subjective assessment of the quality of life of people with rheumatoid arthritis preliminary report [in Polish]. Ortop Traumatol Rehab, 2009, 4 (6), Tasiemski T., Life satisfaction and sports activity in people after spinal cord injury: a comparative Polish-British study [in Polish]. AWF, Poznań Tasiemski T., Knopczyńska A., Wilski M., Quality of life in people after stroke a pilot study [in Polish]. Gerontol Pol, 2010, 18 (3), Biernat E., Stupnicki R., Gajewski A., International Physical Activity Questionnaire (IPAQ) Polish version [in Polish]. Wychow Fiz Sport, 2007, 51 (1), Bauman A., Ainsworth B.E., Bull F.C., Craig C.L., Hagströmer M., Sallis J.F. et al., Progress and pitfalls in the use of the International Physical Activity Questionnaire (IPAQ) for adult physical activity surveillance. J Phys Activ Health, 2009, 6 (Suppl. September), S5 S Hallal P.C., Gomez L.F., Parra D.C., Lobelo F., Mosquera J., Florindo A.A. et al., Lessons learned after 10 years of IPAQ use in Brazil and Colombia. J Phys Activ Health, 2010, 7 (Suppl. July), S259 S Jurakić D., Pedišić Ž., Andrijašević M., Physical activity of Croatian population: cross-sectional study using International Physical Activity Questionnaire. Croat Med J, 2009, 50 (2), , doi: /cmj Piątkowska M., Polish participation in physical activity compared to other countries of the European Union [in Polish]. In: Buśko K., Charzewska J., Kaczanowski K., Modern methods of research activity, fitness and exercise capacity of human [in Polish]. AWF, Warszawa 2010, Norrbrink Budh C., Osteraker A-L., Life satisfaction in individuals with a spinal cord injury and pain. Clin Rehabil, 2007, 21 (1), 89 96, doi: / Biernat E., Gajewski A., Application of the International Physical Activity Questionnaire (IPAQ) the pros and cons, a few methodological solutions and their consequences [in Polish]. In: Buśko K., Charzewska J., Kaczanowski K., Modern methods of research activity, fitness and exercise capacity of human [in Polish]. AWF, Warszawa 2010,

26 J. Łabudzki, T. Tasiemski, Physical activity in blind individuals 20. Hallal P.C., Simoes E., Reichert F.F., Ramos L.R., Validity and reliability of the telephone-administered International Physical Activity Questionnaire in Brazil. J Phys Activ Health, 2010, 7 (3), Wolin K.Y., Heil D.P., Askew S., Matthews C.E, Bennett G.G., Validation of the International Physical Activity Questionnaire-Short among blacks. J Phys Activ Health, 2008, 5 (5), Rosenberg D.E., Bull F.C., Marshall A.L., Sallis J.F., Bauman A.E., Assessment of sedentary behavior with the International Physical Activity Questionnaire. J Phys Activ Health, 2008, 5 (Suppl. 1), S30 S Karakaya I.C., Aki E., Ergun N., Physical fitness of visually impaired adolescent goalball players. Percept Mot Skills, 2009, 108 (1), , doi: /pms Tasiemski T., Wilski M., Mędak K., An assessment of athletic identity in blind and able-bodied tandem cyclists. Hum Mov, 2012, 13 (2), , doi: /v Paper received by the Editor: February 7, 2013 Paper accepted for publication: April 24, 2013 Correspondence address Tomasz Tasiemski Zakład Sportu Osób Niepełnosprawnych Akademia Wychowania Fizycznego ul. Królowej Jadwigi 27/ Poznań, Poland tasiemski@awf.poznan.pl 216

27 2013, vol. 14 (3), Laterality of lower limbs during V2 Alternate in Nordic combined athletes doi: /humo Soňa Jandová *, Jan Charousek Technical University of Liberec, Liberec, Czech Republic Abstract Purpose. The aim of this study was to analyse the foot pressure distribution by cross-country skiers during the push-off phase when using the V2 Alternate skating technique depending on lower limb preference. The study also focused on whether push-off during V2 Alternate would be performed more quickly and in a shorter time interval by the dominant leg than the non-dominant leg. Methods. Data were collected using a pedographic system together with synchronised video recording. Conventional dialogistic methods used in kinanthropology were used to detect the lower-limb lateral preference. Results. Statistically significant differences in the vertical component of force produced by the right/leg lower limbs was observed. However, no statistically significant differences were present in the duration when weight was transferred to one of the lower limbs. Conclusions. Although V2 Alternate is a movement task that is considered to be symmetrical (where left and right leg push-off should be practically identical), the results of the study proved otherwise. In practice, this implies that the explosive force capabilities of cross-country skiers should be trained especially for the non-dominant leg so as to ensure that a fully adequate push-off can be conducted during two-sided skating. Key words: dynamometry, skiing technique, pressure distribution, dominant and non-dominant leg Introduction The occurrence of right and left-sided dominance has been known for a number of years, with research on speech disorders in the 19 th century first documenting this phenomenon. It was discovered that movements of the right side of the body are governed by the left hemisphere of the brain while those of the right side of the body are governed by the left hemisphere of the brain due to the crossing of the main pathways of the brain cortex. However, the cause of laterality, or the preference of humans to use one side of their body over the other, and the factors influencing the ontogenetic development of laterality have been difficult to determine. Blakeslee [1] believes that the most important factors in the development of laterality are biological (the functional asymmetry of the left and right hemispheres) and social. Sovák [2] distinguishes four different categories of laterality, being undetermined, determined right-preference, determined left-preference and crossed laterality, whereas Kováč and Horkovič [3] recognize extreme rightpreference, strong right-preference, weak right-preference (ambidexterity) and left-preference laterality. However, due to specific exercises it is possible to overcome determined laterality in some sports [4]. Some individuals are able to exhibit two-handedness or two-footedness as the result of long-term intensive training. Porac and Coren [5] * Corresponding author. defined lateral preference as being significant during the selection and use of paired body organs during specific activities. According to Vaverka [6], one side of the body in movement activities exhibits better developed coordination, with it being of higher quality and more skilful than the other side. A number of tests were developed to determine laterality. Ruisel [7] proposed a battery of six tests to ascertain the lateral preference of the lower limbs, while Oberleck [8] determined the lateral preference of the lower limbs based on how accurate one is able to kick a ball. Starosta [9], Kollarovits and Gerhát [10], Kasa [11], Šimonek [12] and Hellebrandt et al. [13] have all used standardized tests to estimate laterality. Generally, lower limb activity is less asymmetrical than the upper limbs as the legs work similarly during such activities as walking and running [14]. Of considerable interest is how lateral preference is expressed in sports, with the literature on the subject paying significant attention to skiing. Vaverka and Vodičková [15] examined alpine skiing and found indicators of lower limb laterality in relation to the carved ski arc by dynomometrically measuring differences in foot pressure distribution. A study by Rapp et al. [16] focused on the biomechanical aspects of cross-country skiing by analysing the historical development of skiing technique. Several authors [17, 18] have also emphasized that performance in cross-country skiing is influenced by the force generated at push-off as well as the stamina of the skier. These authors reported that there were higher values of vertical ground reaction force during push-off in the classic skiing style than when skate skiing. A study by Canclini et al. [19], conducted during World Cup races in the 217

28 S. Jandová, J. Charousek, Laterality during V2 skating 1990s, found large differences in the techniques of worldclass cross-country skiers and those who compete at a lower level, especially in terms of slide length, and also observed intra-individual variability of skiing technique. Additional studies by Canclini et al. [20] noted differences in stride frequency, push-off speed and slide length of athletes competing in the World Championships. However, after studying the aforementioned literature, it seems that the interaction of force between the foot and insole during classic and skate skiing has not been fully addressed. The aim of this study was to therefore analyse foot pressure distribution by analysing a group of experienced cross-country skiers by monitoring insole pressure distribution during the push-off phase when using the V2 Alternate skating technique in terms of their lower limb preference on flat terrain at race speed. In relation to the stated objective, this study also focused on whether push-off during V2 Alternate would be performed more quickly and in a shorter time interval by the dominant leg in comparison with the non-dominant leg. A certain uniformity in the values of the vertical component of force during push-off was expected as measurements were performed on high-level athletes and that the long-term training such competitors undergo would offset their determined laterality [4]. Material and methods The study was performed on five male Nordic combined athletes (age: 26.4 ± 5.57 y; height: 1.79 ± 0.03 m; weight: 67.8 ± 2.32 kg) that officially represent the Czech Republic. The study was conducted at the Harrachov ski resort in the Czech Republic. Four of the five cross-country skiers featured right leg dominance while the fifth individual had no preference for which foot he used for push-off. The participants were asked to complete eight runs on flat terrain using various skating techniques. Along a selected 100-metre section they were asked to use the V2 Alternate style (symmetrical push-off) at race speed. Data were collected by dynamographic measurement with simultaneous video recording so as to allow for a more detailed analysis. Measures of the applied force and its duration during the push off-phase was performed using the Pedar in-shoe dynamic pressure measuring system (Novel, Germany) at a frequency of 100 Hz. This system records the pressure of the foot on a sensor insole placed inside the participant s cross-country boot. Recordings of maximum ground reaction force were wirelessly transmitted to a PC, where this data was synchronized to the video recordings using the bundled Novel software. The Wilcoxon test was used to statistically analyse the obtained results. A symmetry index was also used to analyse the differences between the left and right leg. Results Maximum ground reaction force at push-off and its duration during the weight transfer from the left to right leg is presented in Table 1 (an example of the recorded force measurement using the Pedar system is shown in Figure 1). Differences between the dominant and nondominant lower limb were observed for both ground reaction force and its duration. Three of the four crosscountry skiers who prefer to push off with their right leg achieved a higher Fz max (N) value with their dominant (right) leg. The situation was different for the fifth participant with no leg preference for push-off, who achieved similar Fz max (N) values with both the left and right legs. The duration of weight transfer between the dominant to non-dominant lower limb was longer in three of the four skiers who prefer to use their right leg for push-off, while for the remaining two it was shorter. The Wilcoxon rank sum test rejected the null hypothesis for push-off measures of all five competitors except for the duration of weight transfer to the left leg. Significant differences in Fz max values were found, although no significant differences were observed in the duration of weight transfer between the right and left leg (Tab. 1). Overall, although the V2 Alternate skating technique is defined as a symmetrical motor task (where the push-off from the left and right legs should be practically identical), the use of a symmetry index for the measured values found otherwise. The symmetry index (where a value of 1.0 denotes functional similarity of the limbs) for maximum ground reaction force and the duration of weight transfer was and 1.025, respectively. Discussion Due to the fact that few studies have addressed the occurrence of lower limb laterality in cross-country Table 1. Basic statistical characteristics of maximum ground reaction force (Fz max ) registered at push-off and its duration (t) during the weight transfer between left and right leg Variable Right leg Left leg Difference SD SD SD Symmetry index Correlation coeff. Wilcoxon p value Defferences Significant t (s) No Fz max (N) Yes 218

29 S. Jandová, J. Charousek, Laterality during V2 skating Figure 1. Example of the pressure distribution between the left (nondominant) and right (dominant) leg observed using the Pedar system Table 2. Correlation coefficients expressing the relationship between duration and force at push-off Correlation t P (s) t L (s) Fz maxr (N) Fz maxl (N) t P t L Fz maxr Fz maxl t R duration when weight transferred to the right ski; t L duration when weight transferred to the left ski; Fz maxr maximum value of vertical ground reaction force for the right leg; Fz maxl maximum value of vertical ground reaction force for the left leg skiing, a comparison of the results was performed with those of Vaverka and Vodičková [15], where amongst other findings they claim that during downhill skiing the duration of weight transfer on the preferred lower limb is longer and with larger values of force. The correlation coefficients (Tab. 2) calculated in the present study, expressing the relationship between the duration when weight was shifted between one ski and the other and the maximum registered force, found a high negative correlation between these variables. This argues in favour of the hypothesis that a lower value force is replaced by increased duration. In practice, this signifies that for skiers one leg is stronger for push-off while one is more skilful for sliding. In order to confirm this theory it would be necessary to conduct further research on a larger group of participants with both right- and leftsided lower limb dominance. When comparing the results of this study to those of Stöggl at al. [21] on peak pressure during V2 skating, the participants of this study achieved slightly lower values. This may have been caused by the selected group of participants, as in the present study these were skiers who competed in the Nordic combined and were not a group of exclusively cross-country skiers. Future studies should explore this issue with skiers with a clearly determined preference for using the left leg for push-off and also include a larger group of skiers with an undetermined lower limb preference. Conclusions Based on the results, it can be postulated that even for movement regarded as symmetrical there exist statistically significant differences, as was found in the values recorded for maximum vertical ground reaction force in this group of skiers. However, no statistically significant differences were found for the duration when weight was transferred to the preferred foot at push-off. Overall, although V2 Alternate is a movement task that is considered to be symmetrical (where left and right leg push-off should be practically identical), this was found to be otherwise. In practice, this implies that the explosive force capabilities of cross-country skiers should be trained especially for the non-dominant leg so as to ensure that a fully adequate push-off can be conducted during twosided skating. This gives rise to the notion that such athletes should engage in unilateral training [22, 23]. This present study has shown that applying dynamometric measurement is suitable for monitoring the quality of push-off while skate skiing, with additional research needed on a larger group of cross-country and Nordic combined skiers Acknowledgments This study was supported by a grant from the Technical University of Liberec (#5868). References 1. Blakeslee R., The right brain [in German]. Aurum, Freiburg Sovák M., Problems of the left hand [in Slovak]. Jednotná škola, 1956, 2,

30 S. Jandová, J. Charousek, Laterality during V2 skating 3. Kováč D., Horkovič G., Laterality, present studies and perspectives [in Slovak]. Psychologica, 1967, 18, Starosta W., Significance of functional symmetry and asymmetry in sport [in German]. Zeszyty naukowe AWF w Gdańsku, 1983, 7, Porac C., Coren S., Lateral Preferences and Human Behavior. Springer, New York Vaverka F., Laterality and effectivity of human movement the biomechanical point of view. In: Milanović D., Prot F. (eds.), Proceedings of the 4 th International Scientific Conference on Kinesiology Science and Profession Challenge for the Future, University of Zagreb, Croatia 2005, Ruisel I., Functional tests of lateral preference relationships of the lower limbs. Stud Psychol, 1973, 15 (2), Oberleck H., Side phenomenon and typology in sport [in German]. Hoffmann, Schorndorf Starosta W., Movements symmetry and asymmetry in sport training. A guide for coaches [in Polish]. Instytut Sportu, Warszawa Kollarovits Z., Gerhát Š., Evaluation of Kinesthetic-Differentiation Ability. Telesná Výchova a Šport, 1993, 3 (1), Kasa J., Development of Kinesthetic-Differentiation Ability years old children. In Turek M. (ed.), Proceeding International Scientific Conference Nr. 3 of Scientific Society of Physical Education and Sport, Prešov University, Prešov 1994, Šimonek J., Spectrum of coordination ability developing during sport lessons at schools [in Slovak]. In: Turek M. (ed.), Proceeding International Scientific Conference Nr. 3 of Scientific Society of Physical Education and Sport, Prešov University, Prešov 1994, Hellebrandt V., Thurzová, Majherová M., Ramacsay L., Šleboda M., Characteristic of Strength Manifestation of Lower Limb s Kinesthetic-Differentiation Ability in Alpine Skiers. Physical Education and Sports of Children and Youth. FTVŠ, Bratislava 1995, Drnková Z., Syllabová R., Riddle of left-handers and righthanders [in Czech]. Avicenum, Praha Vaverka F., Vodičková S., Laterality of the Lower Limbs and Carving Turns. Biology Sport, 2010, 27 (2), Rapp W., Lindinger S., Müller E., Holmberg H.C., Biomechanics in classical cross-country skiing past, present and future. In: Müller E., Lindinger S., Stoggl T. (eds.), Science and skiing IV. Meyer & Meyer Sport, Oxford 2009, Lindinger S., Müller E., Niessen W., Schwameder H., Kösters A., Comparative biomechanical analysis of modern skating techniques and special skating simulation drills on Word-class level. In: Müller E., Schwameder H., Raschner C., Lindinger S., Kornexl E. (eds.), Science and skiing II. Kovač, Hamburg 2001, Korvas P., Hellebrandt V., Zvonar M., Force and plantar contact area characteristics during push-off in crosscountry skiing. In: Kerstin U. (ed.), Proceedings of ESM August , Alborg University and Aalborg Hospital, Denmark 2012, Canclini A., Pozzo R., Moriconi B., Cotelli F., 3D and 2D kinematic analysis of classical technique in elite cross country skiers during a Word cup race (S.Caterina 1995) and Word championships (Ramsau 1999). In: Müller E., Schwameder H., Raschner C., Lindinger S., Kornexl E. (eds.), Science and skiing II. Kovač, Hamburg 2001, Canclini A., Pozzo R., Cotelli C., Baroni G., 3D kinematics of double poling in classical technique of elite cross-country skiers engaged in world championships races ( ). In: Müller E., Bacharach D., Klika R., Lindinger S., Schwameder (eds.), Science and skiing III. Meyer & Meyer Sport, Oxford 2005, Stöggl T., Kampel W., Müller E., Lindinger S., Double-push skating versus V2 and V1 skating on uphill terrain in cross-country skiing. Med Sci Sports Exerc, 2010, 42 (1), , doi: /MSS.0b013e3181ac Teixeira L.A., Silva M.V., Carvalho M.A., Reduction of lateral asymmetries in dribbling: The role of bilateral practice. Laterality, 2003, 8 (1), Kim K., Cha Y.J., Fell D.W., The effect of contralateral training: Influence of unilateral isokinetic exercise on one-legged standing balance of the contralateral lower extremity in adults. Gait Posture, 2011, 34 (1), , doi: /j.gaitpost Paper received by the Editors: January 9, 2013 Paper accepted for publication: June 3, 2013 Correspondence address Soňa Jandová Technical University of Liberec Institute of Health Studies Studentská Liberec, Czech Republic sona.jandova@tul.cz 220

31 2013, vol. 14 (3), REFLECTIONS ON THE CHANGES OBSERVED IN THE STRUCTURE OF MOTOR SKILLS IN YOUNG ATHLETES doi: /humo Krzysztof Karpowicz *, Małgorzata Karpowicz University School of Physical Education, Poznań, Poland Abstract Purpose. The main objective of the study was to discern what trends are present in the structure of motor skills in young athletes by analyzing a group of basketball players within a context of their sports-specific training. Methods. Data were collected over a five-year period between from 82 young Polish basketball players aged years. In order to determine their motor skill level, the International Physical Fitness Test (IPFT) was administered. Basic somatic parameters, such as height, weight, and body mass index, were also recorded. Results. Analysis of the significant differences between the mean IPFT scores for each year found relatively few statistically significant changes. No statistically significant changes were noted for somatic build. For motor skill level, an upward trend was found for speed, lower limb strength, arm strength, hand strength, abdominal endurance, and agility. Total IPFT scores for each subsequent year indicated a systematic improvement of the participants general physical fitness levels. Conclusions. Despite only few of the results being statistically significant, the general trend of the changes in physical fitness levels is easily observed. Apart from the issue around the selection of surrounding selecting individuals to play in competitive sports, and in particular in which specific sports discipline, it was found that the training loads (such as the one used in boys basketball) have in most cases a positive impact on general physical fitness. Key words: young athletes, basketball, structure of motor skills Introduction Participation in sports play a very large role in the lives of both adults and children. For adults, the practice of various types of sports disciplines does not necessitate meeting any specific prerequisites to being trained. All that is required is meeting the minimal physical, mental, psychological fitness requirements for a given sport. For children and even adolescents, participation in sports is a far more complicated matter. This is especially so when taking into account their participation in the realm of competitive sports, as it is necessary to consider that during these early years of life the body undergoes numerous physical, structural, hormonal, emotional, and psychological changes. As a result, it is important that the athletic training of children and adolescents take into consideration their various phases of development. In all regards, sports for this age group should be treated as part of a gradual, long-term developmental process, all the while keeping in mind the importance of not disturbing the natural rhythm of their development, only stimulating it to follow in the direction of a future sports specialization so as to achieve not only superior results when at full maturity but also the promoted behavior needed to maintain a successful sports career [1, p. 34]. * Corresponding author. Nonetheless, it is well known that the training period children and adolescents undergo when they are still young is one of the most important steps and components that can decide on their future success as adult athletes [2]. The level of preparation put in learning various abilities in this period is known to determine the effectiveness of learning and perfecting technical skills, to have a profound impact on the efficiency of tactical play, and to affect mental disposition [3 5]. Furthermore, the type and level of physical preparedness an athlete possesses is based on a cumulative effect of both the development and shaping of their individual motor skills and abilities. This, however, is not a simple calculation but a specific functional model dependent on such conditions as featuring correct motor development or initial motivation [3, 6]. The conceptual model of the motor preparation of children and adolescents has over the past decades undergone significant change. One of the main factors determining this change was the advancement of knowledge on the body s functional adaptations to phy sical activity and ontogenic background of motor development. In addition, the demands placed on the body when practicing various types of sports have changed [7 10]. Such contemporary knowledge induces one to reflect on the training methodology that has been presently employed at early stages of sports training. This stems from practical problems that have arisen from a lack of a precise characteristics on the interactions of training stimuli, a lack of differentiation in regards to the development of individual abilities, and an incom- 221

32 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes patibility with the natural dynamics of the systematic transformations that occur during puberty. Furthermore, there is the notion that training exercises do not generally effect the body but instead involve specific functional mechanisms leading to specific and not general adaptive changes [10, 11]. This prompts us to consider what relationships exist between general workouts and sports-specific exercises in the sphere of athletic training. It seems that in many cases the principle of applying general workouts is considered to be rather marginal, due to the relatively low effectiveness of such general workouts as well as the problems faced by coaches that require them to specify what concrete measures should be used all the taking into consideration the individual dynamics of motor skills development. Therefore, it seems easier to follow the principles of sports-specific training, or otherwise known as specialized training. Of some assistance, in this regard, should be the use of training stages and their related goals on completing process tasks, which can also help determine the relationship between general and sportsspecific training [12, 13]. In light of the above, it can be assumed that sports effectiveness involves one to possess a sufficiently high level of general physical fitness. This is reflected by the division of the entire training process in various stages, beginning with a general fitness regime followed by targeted and then specialized training, with the aim of the targeted stage to focus training on recognized predispositions and profiling potential motor abilities as a functional base for future specialization [14, p. 179]. The physical fitness profile of a youth athlete is dynamically shaped throughout the entire period of maturation (puberty). Its development is thus determined by a dynamic system of functions and not static components of recognized motor abilities. From this point of view, training conducted during the growth spurt should be directed towards improving general physical fitness and only later should start developing specialized skills when the dynamics of physical changes that occur during puberty diminishes [1, 9, 14 18]. The above considerations, though themselves largely accepted, are in the realm of sports training often overlooked. Although the role of sports in stimulating body development is well known, we often forget that simply increasing training load in specific areas only leads to temporary gains. Hence the training process in sports require constant monitoring, where competitive scores and rankings cannot be the sole criterion for ascertaining a young athlete s improvement [2]. Reviews, evaluations, and eventual corrections of the training process should include such factors as biological development, motor potential, functional capacity, motor abilities, (technical) motor skills, inner motivation, accrued knowledge about the sport, the will to persist, and endurance levels. Only such a system of checks on training effectiveness can allow a coach to individually optimize the type of training and intensity for his/her players. In light of the above considerations, the aim of this study was to determine what trends exist among the structure of motor skills and motor skill level by analyzing a group of young basketball players over a fiveyear period by taking into account the general fitness tasks they perform aimed at forming a functional and technical basis but also those that take into account the basic adequate prerequisites for a player s intended specialization for an individual at this stage in training. The use of young basketball players for verifying this issue is due this being a discipline featuring the most complex movement structures. In this regard, realizing the potential of complex motor activities, learning new motor acts, and the plasticity of ingrained habits all require a high level of concentration abilities, which themselves significantly determine the mastery, improvement, and effective use of technical skills [19 21]. Material and methods Data were collected over a five-year period ( ) on a group of talented young basketball players from the province of Greater Poland, all of whom were competing in the Youth Sports System program as members of their local Provincial Junior Team. The sample consisted of 96 young basketball players years of age. However, only the results of those who participated in all physical fitness tests were subjected to analysis, which amounted to 82 boys (Tab. 1). The study was conducted in partnership between the University of Physical Education in Poznań and the Greater Poland Sports Association. Data were collected each year in the second half of March, with all tests performed on the University premises. The specific days when measurements were taken were subject to the training calendar of the participants as they belonged to different basketball clubs. The participants themselves were a select group of young basketball players who were some of the best players in the province of Greater Poland and were engaged in pre-season training at loads typical of this age group ( cadet level). The training objectives at this phase of the training process were focused on strategic (theory and in competition), tactical (use of different plays), and operational (exercises) goals [22]. The participants weekly training volume was on average eight hours, with approxi- Table 1. Number of participants over the course of the study Year of research Boys (n)

33 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes Table 2. Classification of physical fitness level (International Physical Fitness Test) [24] Physical fitness level mately 40 games played in a season. The end of the study (in 2010) coincided with Greater Poland Cadet A-League championships, in which participants teams played on average 20 games. The participants overall training program at this point in time was focused on improving their individual technical-tactical skills in both offensive and defensive play and was also aimed at preparing them for the basketballs finals in the National Junior Olympics that were to be held at the end of April The structure of the participants motor skills and their motor skill level was assessed using of the International Physical Fitness Test, a test battery that consists of eight basic components allowing for a comprehensive physical fitness assessment. Its origins date back to the 1964 Olympic Games held in Tokyo, Japan. On this occasion, the International Committee on the Standardization of Physical Fitness Tests was organized to unify and standardize the methods available for assessing physical fitness levels. After many years of work, the end result was then finalized and approved at a conference held in Oxford, England. Today, after a history of more than 40 years, the International Physical Fitness Test is often criticized as outdated. However, it is still widely used by many coaches and researchers as an uncomplicated tool in measuring motor skill performance [23]. In Poland, it is also recommended by the Ministry of Sport and Tourism as a useful gauge in determining the physical fitness levels of young athletes. Measures of participants motor skill level and flexibility were performed in accordance with the recommendations set forth by the International Physical Fitness Test [24]. Speed was measured by the 50 m speed test (also known as a sprint test); endurance, based on the 1000 m run; and agility, evaluated by a 4 10 m shuttle run. Measures of strength included evaluating lower limb explosive strength by the standing long jump and abdominal endurance with the 30-s sit-up test. Grip strength was measured by a hand dynamometer, while upper limb and shoulder strength with the bent-arm hang or a pull-up test on a bar. Trunk flexibility is an anatomical feature of the body that describes the range of movement of the spine and hip and was measured by the standing forward bend. The results obtained for each test component were then converted to a point scale (based on a T-scale) depending on chronological age, as for young athletes this is one of the main selection criterion for joining different training groups at various stages of training. It was for this reason the scores were not age-adjusted for body height, which is used as an indicator of somatic development. The results were then compared to the norms proposed by Pilicz et al. (Tab. 2). Basic somatic parameters such as body height and mass were also measured and used to calculate the participants BMI [25]. Basic statistical methods were used to analyze the obtained scores, which included calculating the arithmetic means, standard deviations, and minimum and maximum values. Significant differences between each year s mean scores were calculated by Tukey s Honestly Significant Difference (HSD) test [26]. Results Point range (regardless of age or sex) High 481 and above Average Low 319 and below The descriptive characteristics of the results for each year are presented in Table 3 and include the means, standard deviations, and minimum and maximum values. The results from the International Physical Fitness Test for each individual are provided as point values standardized for age. Analysis was first performed on the significant differences between the mean results by employing Tukey s Honestly Significant Difference test [26], with the results presented in Table 4. Analysis of the significance of differences between the mean scores in the following years of research found statistically significant differences between 2006 and 2007 (based on the total number of points on the IPFT) as well as between 2009 and 2010 (hand strength and agility capabilities). Based on the assumption that the differences in the results during the analyzed period may have unevenly progressed, as confirmed by the age-related differences (Tab. 4), it was decided to determine what trends were present in terms of the development of the analyzed parameters. Using the method of least squares, the time frame of these changes were plotted as first- or seconddegree polynomials [26], with the results presented in Figures The presented figures show that the parameters characterizing somatic build in the subsequent years of the study are similarly shaped, with the curves characterized by a sinusoidal pattern, finding a coefficient of determination (R 2 ) between 74% to 98%. With regard to motor skill levels, as determined by using the International Physical Fitness Test, an upward trend was noted in terms of running speed (50 m run), lower limb strength (standing long jump), arm strength (pull-ups), hand strength (dynamometer), abdominal endurance (sit-ups), and agility (4 10 m shuttle run). However, the opposite was found when analyzing the results of the endurance race (1000 m run). The relatively low level of resistance to fatigue steadily declined from 2008, which contrasted to the steady increase observed 223

34 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes Table 3. Statistical characteristics of the scores attained over the course of the study Year Body height Body mass BMI 50 m run Long jump 1000 m run Hand grip strength Pull-ups 4 10 m run Sit-ups Standing forward bend IPFT score cm kg kg/m 2 pts. pts. pts. pts. pts. pts. pts. pts. pts Mean Minimum Maximum Standard deviation Mean Minimum Maximum Standard deviation Mean Minimum Maximum Standard deviation Mean Minimum Maximum Standard deviation Mean Minimum Maximum Standard deviation IPFT International Physical Fitness Test Table 4. Significant differences between the participants mean scores over the course of the study (Tukey s HSD test) Body height Body mass BMI 50m run Long jump 1000 m run Hand grip strength Pull-ups 4 10 m run Sit-ups Standing forward bend IPFT score cm kg kg/m 2 pts. pts. pts. pts. pts. pts. pts. pts. pts. Mean Mean Difference Significance * Mean Mean Difference Significance Mean Mean Difference Significance Mean Mean Difference Significance * * * * denotes significant differences at p 0.05; IPFT International Physical Fitness Test 224

35 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes [cm] 195 y = x x x R² = [pts.] 65 y = x x R² = Figure 1. Body height Figure m run [kg] y = x x x R² = Figure 2. Body mass [pts.] y = x R² = Figure 7. Hand grip strength 24 y = x x x R² = [pts.] 60 y = x R² = Figure 3. BMI Figure 8. Pull-ups [pts.] 70 y = x R² = [pts.] 75 y = x R² = Figure m run Figure m run [pts.] y = x R² = Figure 5. Long jump [pts.] y = x2 2,545x R² = Figure 10. Sit-ups 225

36 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes [pts.] [pts.] y = 0.605x x R² = Figure 11. Standing forward bend y = x R² = Figure 12. IPFT score Figure 15. Structure of motor skills profile in 2008 (IPFT scores) Figure 13. Structure of motor skills profile in 2006 (IPFT scores) Figure 16. Structure of motor skills profile in 2009 (IPFT scores) Figure 14. Structure of motor skills profile in 2007 (IPFT scores) Figure 17. Structure of motor skills profile in 2010 (IPFT scores) 226

37 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes between Overall, the participants total point score on the International Physical Fitness Test over the course of the study pointed to a systematic improvement in their physical fitness. Analysis of the participants structure of motor skills, based on their motor skill level profiles normalized for mean and standard deviations, found that it also underwent change (Fig ), clearly indicating an upward trend. This is particularly evident in the results from 2010, where most of the trials were found to be higher than the mean by about half a standard deviation. The only exception were the results from the 1000 m run, which in 2010 were found to be half a standard deviation lower than the arithmetic mean. Discussion As an indicator of body development and general health, physical fitness is a focal subject in numerous studies analyzing physical culture. One item of interest in the literature on the subject is analysis of the intergenerational differences in motor skill development, with studies repeatedly finding that it has a regressive character [27 29]. This has led some to justify their interpretation of such changes in terms of the formation of a new type of physical fitness barometer as a consequence of the changes in lifestyle now faced in the modern world. This includes the adoption by today s youth a different system of values, including their preferred form and dimension of physical activity, which naturally affects their participation in sports. Nonetheless, as overall physical fitness is the cornerstone in learning sports techniques and tactics, there still exists a need to separately train motor skills [30 32]. The purpose of the present study was to determine what trends are present in the structure of motor skills and the motor skill level of young basketball players by analyzing them over a period of five years. As a result, this study can be used as a reference for comparing the motor development of subsequent generations of talented young athletes. In the course of the study, it was found that the structure of motor skills of the participants showed relatively comprehensive and uniform motor preparation. The only exception to this general trend was the young basketball players endurance levels. This may obviously have a detrimental outcome, as basketball is a discipline that requires both speed and stamina. However, the differences for this component were not statistically significant. Analysis of how the participants scored on the International Physical Fitness Test over the studied time frame indicates that their overall physical fitness levels systematically improved. Although the differences in only a few cases were statistically significant, the general trend is easily observed. This is contrary to the aforementioned regressive trend observed among successive generations, which may likely be due to the participants involvement in athletic training, which obviously positively stimulates body development. In this regard, sports for children and youth should have a general fitness, health, and educational character and, above all, it should be performed in tune with their biological and physiological development. The physical fitness level of the participants, as based on the classification standards of the International Physical Fitness Test [24], can be described as average, although the results recorded in 2008 and 2009 had them already approaching high levels of physical fitness. By 2010 they were classified at the lower limit of the high level. It is should be therefore expected that this trend for future age groups ought to be maintained. The significant improvement in the motor skill level of each subsequent age group seems to differ from the observations put forward by advantage Przewęda [33], who studied the physical fitness of Polish youth. He believes that if the current trend in physical activity levels is maintained, then one could then speak of the predominance of physical fitness based on speed-agility over physical fitness determined by strength. Conclusions Apart from the issue around the selection of individuals who should play competitive sports, and in particular in which specific discipline, while also taking into consideration the significant impact of such a choice on the morpho-functional characteristics of young athletes, it can be concluded that training loads at this stage (such as the one used in boys basketball) have in most cases a positive impact on general physical fitness, as an indicator of human health and development, and consequently on sports performance. References 1. Raczek J., The basis for the sports training of children and youth [in Polish]. RCMSKFiS, Warszawa Ważny Z., The modern system of training in competitive sports [in Polish]. SiT, Warszawa Fraser-Thomas J.L., Cote J., Deakin J., Youth sport programs: avenue to foster positive youth development. Physical Education Sport Pedagogy, 2005, 10 (1), 19 40, doi: / Starosta W., Selected biosocial determinants of the effectiveness of the training of sports of children and youth. In: Bergier J. (ed.), Sport of children and youth at the turn of the century [in Polish]. IWFiS, Biała Podlaska 2000, Sozański H., Śledziewski D., Kielak D., Sukniewicz M., Perkowski K., Siwko F., Theoretical basis of development of physical fitness in the process of sports training of children and teenagers [in Polish]. AWF, Warszawa Schmidt R.A., Lee T.D., Motor control and learning. A behavioral emphasis. Human Kinetics, Champaign Ryguła I., The research process in the sport science [in Polish]. AWF, Katowice

38 K. Karpowicz, M. Karpowicz, Structure of motor skills in young athletes 8. Mynarski W., Żywiczka A., The empirical model of coordination considerations of man fitness preparation [in Polish]. AWF, Katowice Sozański H., The diversity of sports development of young players, depending on the nature of the training [in Polish]. AWF, Warszawa Raczek J., The concept of the physical preparation of children and youth [in Polish]. Roczniki Naukowe, 1985, 13, Hirtz P., Starosta W., Sensitive and critical periods of motor coordination development and its relation to motor learning. J Hum Kinetics, 2002, 7, Thomas J.R., Nelson J.K., Research methods in physical activity. Human Kinetics, Champaign Naglak Z., Time structure of training athletes specializing in team sports games. In: Ryguła I. (ed.), Factors determining the effectiveness of sports competition in basketball [in Polish]. AWF, Katowice 1995, Sozański H. (ed.), The basis of the theory of training [in Polish]. RCM-SKFiS, Warszawa Sozański H., Adamczak J., Siewierski M, Periodization of sports training process theory and reality. In: Strzelczyk R., Karpowicz K. (eds.), Periodization of sports training process theory and reality. Monografie 407 [in Polish]. AWF, Poznań 2012, Raczek J., Model of sports training of children and youth ideas, controversies, proposals [in Polish]. Sport Wyczynowy, 1984, 5, Kosendiak J., Aims and objectives of training at an early stage, and its implementation. In: Strzelczyk R., Karpowicz K. (eds.), Periodization of sports training process theory and reality. Monografie 407 [in Polish]. AWF, Poznań 2012, Karpowicz K., Strzelczyk R., The structure of motor effects level of young sportsman at the direction stage of training. In: Strzelczyk R., Karpowicz K. (eds.), Periodization of sports training process theory and reality. Monografie 407 [in Polish]. AWF, Poznań 2012, Starosta W., The coordination and condition abilities in team sports games. In: Bergier J. (ed.), Science in sports team games [in Polish]. IWFiS, Biała Podlaska 1995, Karpowicz K., Karpowicz M., Janowski J., Konarski J., Strzelczyk R., The general and special fitness and the sport level of young basketball players. In: Kuder A., Perkowski K., Śledziewski D. (eds.), The directions of improvement training and sports fight diagnostics [in Polish]. PTNKF, Warszawa 2006, Czerwiński J. (ed.), Control training and sportsmanship in team games [in Polish]. AWFiS, Gdańsk Naglak Z., The theory of team sport game. Player training [in Polish]. AWF, Wrocław Szopa J., Mleczko E., Żak S., The basis of anthropomotorics [in Polish]. PWN, Warszawa Pilicz S., Przewęda R., Trześniowski R., Point scale to assess the physical fitness of Polish youth [in Polish] AWF, Warszawa Drozdowski Z., Anthropology of sport [in Polish]. PWN, Warszawa Stanisz A., Affordable statistics course using STATISTI- CA PL on the examples of medicine [in Polish]. StatSoft Polska, Kraków Przewęda R., Dobosz J., The physical condition of the Polish youth [in Polish]. AWF, Warszawa, Studia i Monografie, 98, Jarosz M. (ed.), Obesity, nutrition, physical activity, health of Polish people [in Polish]. Instytut Żywności i Żywienia, Warszawa Dobosz J., The individual evaluation of physical changes in the perspective of population changes. In: Charzewska J. (ed.), Biosocial aspects of the development of contemporary Polish youth during the ripening [in Polish]. AWF, Warszawa 2007, Wachowski E., Strzelczyk R., Advantages of motor properties [in Polish]. Trening, 1991, 1, Czerwiński J., Jastrzębski Z., The process of training in team sports games. Theory and practice [in Polish]. AWFiS, Gdańsk Czerwiński J., Sozański H. (ed.), Modern concepts of training in team sports games [in Polish]. AWFiS, Gdańsk Przewęda R., The status of the efficiency development of children and youth in Poland [in Polish]. Biuro Studiów i Ekspertyz Kancelarii Sejmu, Warszawa Paper received by the Editors: August 22, 2012 Paper accepted for publication: June 3, 2013 Correspondence address Krzysztof Karpowicz Zakład Teorii Sportu Akademia Wychowania Fizycznego ul. Królowej Jadwigi 27/ Poznań, Poland karpowicz@awf.poznan.pl 228

39 2013, vol. 14 (3), Methods of determining hip joint centre: their influence on the 3-D kinematics of the hip and knee during the fencing lunge doi: /humo Jonathan Sinclair 1, *, Lindsay Bottoms 2 1 University of Central Lancashire, Preston, United Kingdom 2 University of East London, London, United Kingdom Abstract Purpose. The lunge is a fundamental offensive fencing technique, common to all contemporary fencing styles. Therefore, when using 3-D kinematic analysis to quantify lower extremity rotations during the fencing lunge, it is important for researchers to correctly interpret this movement. Locating the centre of the hip is required to accurately quantify hip and knee joint rotations, with three non-invasive techniques using anatomical, functional and projection methods currently available for the estimation of hip joint centre. This study investigated the influence of these three techniques on hip and knee joint kinematics during the fencing lunge. Methods. Three-dimensional kinematics of the lunge were collected from 13 experienced epee fencers using an eight-camera motion capture system. The 3-D kinematics of the lunge were quantified using the three hip joint centre estimation techniques. Repeated measures ANOVAs were used to compare the discrete 3-D kinematic parameters, and intra-class correlations were employed to identify similarity across the 3-D kinematic waveforms from the three techniques. Results. The results indicate that whilst the kinematic waveforms were similar (R ); significant differences in discrete parameters were also evident at both the hip and knee joint in the coronal and transverse planes. Conclusions. It appears based on these observations that different hip joint centre locations can significantly influence the resultant kinematic parameters and cannot be used interchangeably. Key words: hip joint centre, kinematics, fencing, lunge Introduction A powerful fencing lunge is fundamental to successful performance, it being the most common attack with all three fencing weapons: the foil, epee and sabre. The lunge is an explosive movement that begins from an en-guard position, with the feet shoulder-width apart, where the back foot is 90 degrees to the forward-facing front foot. The fencer then straightens their sword arm and pushes off from their back leg while lifting up and kicking out their front leg for the lunge. To score, a fencer lunges from the en-guard position quickly closing the distance to the opponent and touches the opponent with his/her weapon. Unlike the forward lunge common in many other sports, the fencing lunge maintains a perpendicular orientation of the feet, where the sole of the non-leading foot remains planted on the ground and the non-leading leg is forcefully and almost completely extended. When using 3-D kinematic analysis to quantify lower extremity rotations during the fencing lunge, it is important for researchers to correctly interpret this movement. In recent years, efforts have been made to improve 3-D kinematic techniques during motion analysis in order to accurately model and track body segments. Movement artefact has been reduced via the utilization of the calibrated anatomical systems technique (CAST), * Corresponding author. using tracking clusters placed on body segments to create technical coordinate systems [1]. However, modelling of the thigh segment remains difficult [2], particularly at its proximal insertion with the pelvis, as there are number of techniques that are available for the location of the hip joint centre. Locating the centre of the hip is required to calculate hip joint rotations and moments in 3-D kinematic analysis [3 5]. The hip joint centre is an important identifying landmark in human movement analysis as it allows for the determination of the anatomical reference frame of the femur [1]. A number of techniques currently exist that include anatomical [6], functional [7, 8] and projection [9] methods, all of which may influence the resultant hip and knee joint profiles [5]. Although the validity of each method has been reported to justify their utilization, there is currently a lack of information regarding the influence of the three available hip joint centre location techniques on 3-D kinematic parameters during fencing movements and the interchangeable use of each technique [10]. Furthermore, whilst investigations have been conducted whereby the accuracy of each technique in determining the anatomical position of the hip joint centre was examined using radiographic imaging, there is a paucity of information regarding the influence of the different techniques upon the resultant kinematic waveforms and discrete variables. Therefore, the aim of the current investigation was to compare the 3-D kinematics of the fencing lunge 229

40 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge quantified using three different (anatomical, projection and functional) hip joint centre estimation techniques via both discrete variable and waveforms analyses. Material and methods Thirteen participants including eight males and five females volunteered to take part in this investigation. All were competitive epee fencers with a minimum of five years experience. Participants were free of injury at the time of data collection and provided written informed consent in accordance with the Declaration of Helsinki, with the procedure utilized for this investigation approved by the ethical committee at the University of Central Lancashire. The mean characteristics of the participants were: age ± 4.50 years, height ± 7.60 cm and body mass ± 8.49 kg. A statistical power analysis was conducted using Hopkins method to reduce the probability of type II error and define the minimum number of participants needed for this examination. It was found that the sample size was sufficient to provide more than 80% statistical power. The fencers completed a suitable warm-up and were allowed time to familiarize themselves with the experimental protocol prior to the commencement of data collection. They were then required to complete 10 trials hitting a dummy with their weapon whilst returning to a starting point (pre-determined by each participant prior to the commencement of data capture) following each trial to control lunge distance. The participants began with their right (lead) foot on a force platform (Kistler Instruments Ltd., England), which was embedded in the floor (Altrosports 6mm, Altro Ltd., England) of the biomechanics laboratory where the study was performed. Kinematic data were captured at 200 Hz via an eightcamera motion analysis system (Qualisys Medical AB, Sweden). Calibration of the required capture volume was performed before each data collection session. Only calibrations which produced average residuals of less than 0.85 mm for each camera for a mm wand length and point residuals above 4000 in all cameras were accepted prior to data collection. The marker set used for the study was based on the calibrated anatomical systems technique (CAST) [1]. In order to define the lead leg s foot, shank and thigh, retroreflective markers were attached unilaterally to the calcaneus, 1st and 5th metatarsal heads, medial and lateral malleoli, medial and lateral epicondyle of the femur and greater trochanter. To define the pelvis, additional retroreflective markers were placed on the anterior (ASIS) and posterior (PSIS) superior iliac spines. All markers were positioned by the lead author. Rigid tracking clusters were positioned on the shank and thigh. Each rigid cluster comprised of four 19 mm diameter spherical reflective markers mounted to a thin sheath of lightweight carbon fibre with length-to-width ratios in accordance with Cappozzo et al. [11]. A static trial was conducted with the participant in the anatomical position in order for the positions of the anatomical markers to be referenced in relation to the tracking clusters, following which the non-technical markers (i.e. medial and lateral malleoli, medial and lateral epicondyle of the femur) were removed. The anatomical technique that was used in the present study was based on the recommendations of Bell et al. [6] via the inter-asis breadth. This method places the hip joint centre 14% medial, 22% posterior and 30% distal from the ipsilateral (right) ASIS (Fig. 1). The projection technique was also based on previously established recommendations [9], where this method estimated HJC as a three-dimensional point, located at one-quarter of the distance along a line from the ipsolateral (right) to the contralateral (left) greater trochanter markers during the static trials (Fig. 1). To define the functional HJC, participants performed five sequential flexion-extension and abduction-adduction movements of the right hip at a self-selected velocity followed by a cycle of full hip circumduction [8]. Flexion-extension and abduction-adduction ranges of movement were in the order of 45 and 40, respectively. Trials were processed by Qualisys Track Manager in order to identify the anatomical and tracking markers Figure 1. Pelvic, thigh, tibial and foot segments, with segment co-ordinate system axes (P XYZ pelvis, S XYZ shank; AT XYZ anatomical thigh, PT XYZ projection thigh, FT XYZ functional thigh) 230

41 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge and then exported as C3D files. Kinematic parameters were quantified using Visual 3-D (C-Motion Inc., USA) after marker data were smoothed using a low-pass Butterworth 4 th order zero-lag filter at a cut-off frequency of 12Hz. This frequency was selected as being the frequency at which 95% of the signal power was contained below. Three-dimensional kinematics of the hip and knee were calculated using an XYZ cardan sequence of rotations (where X was flexion-extension, Y was abduction-adduction and Z was internal-external rotation) [12]. All data were normalized to 100% of the lunge movement, with the processed trials then averaged. The three-dimensional kinematic measures from the hip and knee that were extracted for statistical analysis were: 1) angle at initiation of movement, 2) angle at completion of lunge, 3) range of motion from initiation to completion of the lunge, 4) peak angle, 5) relative range of motion from initiation to peak angle 6) angular velocity at initiation, 7) angular velocity at completion of lunge, 8) peak angular velocity, 9) angular acceleration at initiation, 10) angular velocity at completion of lunge and 11) peak angular acceleration. Descriptive statistics including means and standard deviations of the 3-D kinetic and kinematic parameters were calculated for each hip joint centre prediction technique. Differences between the parameters were examined using repeated measures ANOVA with significance accepted at the p 0.05 level. Appropriate post-hoc analyses were conducted using a Bonferroni correction to control for type I error. Effect sizes were calculated using ŋ 2. Cohen s suggestion on effect sizes was adopted (small ŋ 2 < 0.01; medium 0.06 and large 0.13). If the sphericity assumption was violated then the degrees of freedom were adjusted using the Greenhouse-Geisser correction. In addition, intra-class correlations were utilized to compare between the sagittal, coronal, and transverse plane waveforms using the three different techniques. The Shapiro-Wilk statistic for each condition was used to confirm that data were normally distributed. All statistical procedures were conducted using SPSS 19.0 statistical software (SPSS Inc., USA). Results Figures 2 4 present the mean 3-D angular kinematics of the hip and knee joint during the lunge. Tables 1 6 present the 3-D kinematic parameters from the hip and knee observed as a function of the hip joint centre esti- Figure 2. Hip and knee kinematics in the (a.) sagittal, (b.) coronal and (c.) transverse planes as a function of hip joint centre location (black line anatomical technique, grey line functional technique, dotted line projection technique) Figure 3. Hip and knee joint velocities in the (a.) sagittal, (b.) coronal and (c.) transverse planes as a function of hip joint centre location (black line anatomical technique, grey line functional technique, dotted line projection technique) 231

42 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge Table 1. Hip joint kinematics (means and standard deviations) as a function of hip joint centre technique Hip Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Angle at Initiation ( ) ± ± ± Angle at Completion ( ) ± ± ± Range of Motion ( ) ± ± ± Relative Range of Motion ( ) ± ± ± Peak Flexion ( ) ± ± ± Y (+ adduction/ abduction) Angle at Initiation ( ) ± ± ± 8.49 Angle at Completion ( ) ± ± ± Range of Motion ( ) ± ± ± Relative Range of Motion ( ) ± ± ± Peak Abduction ( ) ± ± ± 8.76 Z (+ internal/ external) Angle at Initiation ( ) ± ± ± 9.96 ** Angle at Completion ( ) ± ± ± * Range of Motion ( ) ± ± ± Relative Range of Motion ( ) ± ± ± Peak Internal rotation ( ) ± ± ± * * significant at p 0.05; ** significant at p 0.01; significantly different from the functional technique; significantly different from the projection technique Table 2. Knee joint kinematics (means and standard deviations) as a function of hip joint centre projection technique Knee Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Angle at Initiation ( ) ± ± ± Angle at Completion ( ) ± ± ± 8.43 Range of Motion ( ) ± ± ± Relative Range of Motion ( ) ± ± ± Peak Flexion ( ) ± ± ± Y (+ adduction/ abduction) Angle at Initiation ( ) 5.93 ± ± ± 8.01 Angle at Completion ( ) ± ± ± ** Range of Motion ( ) 6.22 ± ± ± 4.77 Relative Range of Motion ( ) 3.97 ± ± ± 4.26 Peak Adduction ( ) 1.96 ± ± ± 8.23 Z (+ internal/ external) Angle at Initiation ( ) 3.81 ± ± ± * Angle at Completion ( ) 3.00 ± ± ± Range of Motion ( ) 8.56 ± ± ± 4.70 Relative Range of Motion ( ) ± ± ± 7.14 Peak External rotation ( ) ± ± ± * * significant at p 0.05; ** significant at p 0.01; significantly different from the functional technique; significantly different from the projection technique 232

43 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge mation technique. The results indicated that the kinematic waveforms were similar but significant differences in discrete parameters were also evident. Hip joint angles In the transverse plane, a significant main effect F(2, 24) = 6.53, p 0.01, ŋ 2 = 0.35 was observed for the magnitude of rotation at the commencement of the lunge movement. Post-hoc analysis revealed that the anatomical technique was associated with significantly (p = 0.02) more external rotation than the functional method. A significant main effect F(2, 24) = 4.15, p 0.01, ŋ 2 = 0.26 was also observed for the magnitude of rotation at the completion of the movement. Post-hoc analysis revealed that the anatomical technique was associated with significantly (p = 0.04) less external rotation than the functional method. Finally, a significant main effect F(2, 24) = 4.50, p 0.05, ŋ 2 = 0.27 was observed for the magnitude of peak transverse plane rotation. Post-hoc analysis revealed that the anatomical technique was associated with significantly (p = 0.04) less external rotation than the functional method. Comparisons between hip waveforms using the three different methods revealed strong correlations in all three planes of rotation: sagittal (R 2 = 0.99), coronal (R 2 = 0.97) and transverse (R 2 = 0.96). Knee joint angles In the coronal plane, a significant main effect F(1.13, 13.58) = 5.95, p 0.01, ŋ 2 = 0.33 was observed for the magnitude of rotation at the completion of the lunge movement. Post-hoc analysis revealed that the functional method was associated with significantly (p = 0.04) more adduction in comparison with the anatomical technique. In the transverse plane, a significant main effect F(2, 24) = 3.67, p 0.05, ŋ 2 = 0.26 was also observed for the magnitude of rotation at the commencement of the lunge movement. Post-hoc analysis revealed that the projection method was associated with significantly (p = 0.04) more external rotation than the anatomical technique. Finally, a significant main effect F(2, 24) = 4.88, p 0.05, ŋ 2 = 0.20 was observed for the magnitude of peak transverse plane rotation. Post-hoc analysis revealed that the projection method was associated with significantly (p = 0.04) more external rotation than the anatomical technique. Comparisons between knee waveforms using the three different methods revealed strong correlations in all three planes of rotation: sagittal (R 2 = 0.99), coronal (R 2 = 0.96) and transverse (R 2 = 0.94). Hip joint velocities No significant (p 0.05) main effects were observed for any of the hip joint angular velocity parameters observed as a function of hip joint centre location technique. Comparisons between hip waveforms using the three different methods revealed strong correlations in all three planes of rotation: sagittal (R 2 = 0.99), coronal (R 2 = 0.98) and transverse (R 2 = 0.95). Hip joint accelerations No significant (p 0.05) main effects were observed for any of the hip joint angular acceleration parameters observed as a function of hip joint centre location technique. Comparisons between hip waveforms using the three different methods revealed strong correlations in all three planes of rotation: sagittal (R 2 = 0.99), coronal (R 2 = 0.97) and transverse (R 2 = 0.95). Figure 4. Hip and knee joint accelerations in the (a.) sagittal, (b.) coronal and (c.) transverse planes as a function of hip joint centre location (black line anatomical technique, grey line functional technique, dotted line projection technique) Knee joint accelerations No significant (p 0.05) main effects were observed for any of the knee joint angular acceleration parameters observed as a function of hip joint centre location tech- 233

44 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge Table 3. Hip joint velocities (means and standard deviations) as a function of hip joint centre technique Hip Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Velocity at Initiation ( s 1 ) ± ± ± Velocity at Completion ( s 1 ) ± ± ± Peak Velocity ( s 1 ) ± ± ± Y (+ adduction/ abduction) Velocity at Initiation ( s 1 ) ± ± ± Velocity at Completion ( s 1 ) ± ± ± Peak Velocity ( s 1 ) ± ± ± Z (+ internal/ external) Velocity at Initiation ( s 1 ) ± ± ± Velocity at Completion ( s 1 ) 3.58 ± ± ± 7.99 Peak Velocity ( s 1 ) ± ± ± Table 4. Knee joint velocities (means and standard deviations) as a function of hip joint centre technique Knee Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Velocity at Initiation ( s 1 ) ± ± ± Velocity at Completion ( s 1 ) ± ± ± Peak Velocity ( s 1 ) ± ± ± Y (+ adduction/ abduction) Velocity at Initiation ( s 1 ) 3.66 ± ± ± Velocity at Completion ( s 1 ) 8.38 ± ± ± Peak Velocity ( s 1 ) ± ± ± Z (+ internal/ external) Velocity at Initiation ( s 1 ) ± ± ± Velocity at Completion ( s 1 ) 2.31 ± ± ± Peak Velocity ( s 1 ) ± ± ± nique. Comparisons between hip waveforms using the three different methods revealed strong correlations in all three planes of rotation: sagittal (R 2 = 0.99), coronal (R 2 = 0.98) and transverse (R 2 = 0.95). Discussion The aim of the current investigation was to compare the 3-D kinematics of the hip and knee during the fencing lunge using three different hip joint centre location techniques. This study represents the first to examine the differences between hip joint centre estimation techniques when quantifying lower extremity kinematics during the fencing lunge. In the sagittal plane, no differences were observed between discrete parameters for the hip or knee joint between any of the three hip joint centre locations techniques (Tab. 1 6). In addition to this, the highest intraclass (R ) correlations were observed for the sagittal plane waveforms indicating a high level of similarity across all techniques in the sagittal plane. In the coronal and transverse planes, although the intra-class correlations showed a good level of agreement between waveforms (R ), significant differences between the three hip joint centre estimation techniques were observed for both the hip and knee angles. This suggests that different techniques for the determination of hip joint centre may affect overall discrete kinematic parameters. It should be noted that the anatomical technique was typically different from the functional and projection methods in the transverse plane. This concurs with the findings of Eng and Winter [13] and Bowsher and Vaughan [14], who both noted that transverse plane hip joint kinematics were 234

45 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge Table 5. Hip joint accelerations (means and standard deviations) as a function of hip joint centre technique Hip Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) ± ± ± Peak Acceleration ( s 2 ) ± ± ± Y (+ adduction/ abduction) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) ± ± ± Peak Acceleration ( s 2 ) ± ± ± Z (+ internal/ external) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) ± ± ± Peak Acceleration ( s 2 ) ± ± ± Table 6. Knee joint accelerations (means and standard deviations) as a function of hip joint centre technique Knee Anatomical Projection Functional Mean ± SD Mean ± SD Mean ± SD X (+ flexion/ extension) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) ± ± ± Peak Acceleration ( s 2 ) ± ± ± Y (+ adduction/ abduction) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) ± ± ± Peak Acceleration ( s 2 ) ± ± ± Z (+ internal/ external) Acceleration at Initiation ( s 2 ) ± ± ± Acceleration at Completion ( s 2 ) 2.90 ± ± ± Peak Acceleration ( s 2 ) ± ± ± sensitive to anatomical frame alterations. It is likely that this observation is a reflection of the more medial position of the HJC in the anatomical technique compared with the functional and projection configurations. Given that the co-ordinate systems of the segments are based on the positions of the proximal and distal joint centres, the pose of the thigh segment is altered. This caused the thigh segment to be more externally rotated leading to increases in hip external rotation and knee internal rotation in the anatomical technique. This observation concurs with the findings of Sinclair et al. [10], who also observed statistical differences when examining 3-D kinematics of the hip and knee during running when using three different hip joint centre location techniques. However, the extent of the differences between hip joint centre location techniques can be conceptualized through inspection of the effect sizes, which are considered small to moderate based on Cohen s recommendations [15]. This indicates that whilst there are significant differences between techniques, the overall influence of the hip joint centre location on 3-D kinematic parameters is generally low. Nonetheless, the observations from the current investigation may have potential clinical significance particularly in movements such as the lunge where high loading of the lower extremities occurs [16] in conjunction with relatively large coronal transverse plane motions of the hip and knee joints. Mizuno et al. [17], Horton and Hall [18] and Koga et al., [19] documented that increases in non-sagittal rotations at the hip and knee, which were shown to be significantly greater in the functional and projected techniques, are associated with the a etiology of injury to the lower extremities. Therefore it appears that researchers should carefully consider their 235

46 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge choice of hip joint centre location technique when quantifying non-sagittal rotations and selecting clinical normative data, as it may affect the interpretation of their data. It should be noted that the hip joint centre location has little influence on first and second derivative angular parameters. This leads to the conclusion that alterations in hip joint centre location can have a significant influence on angular displacement information, there does not seem to been any effects when quantifying angular kinematics for derived angular velocity and acceleration information. However, whilst this study considered angular displacement and derivative information, joint moments using inverse dynamics are also important in describing musculoskeletal movements [20]. Future work may wish to examine the influence of the hip joint centre on hip and knee joint moments during the fencing lunge. That no radiographic measures were included in the current investigation may serve as a potential limitation, as the accuracy in determining the true location of the hip joint centre could not be documented. However, this is an invasive technique that is rarely used due to institutional ethical concerns and that radio-graphical planar films can be susceptible to parallax errors and poor control of participant positioning [21]. Furthermore, whilst this study provided information regarding the differences in discrete parameters and kinematic waveforms, the inter/intra-examiner reliability in defining the hip joint centre was not examined in terms of these parameters. This is a factor that future work may wish to address before an optimal estimation technique can be recommended. Conclusions In summary, whilst it is beyond the scope of this report to determine an optimal technique for the estimation of the hip joint centre, it does provide important information in that the different techniques yielded statistically significantly different discrete parameters when quantifying rotations outside the sagittal plane. Therefore, it appears that they may not be able to be used as interchangeably as has previously been commonplace in the literature on the subject and that cross-study comparison of hip and knee joint kinematics during the fencing lunge should be made with caution. Acknowledgements Our thanks go to Glen Crook for his technical assistance. References 1. Cappozzo A., Catani F., Della Croce U., Leardini A., Position and orientation in space of bones during movement: Anatomical frame definition and determination. Clin Biomech, 1995, 10 (4), Besier T.F., Sturnieks D.L., Alderson J.A., Lloyd D.G., Repeatability of gait data using a functional hip joint centre and a mean helical knee axis. J Biomech, 2003, 36 (8), , doi: /S (03) Cappozzo A., Leo T., Pedotti A., A general computing method for the analysis of human locomotion. J Biomech, 1975, 8 (5), , doi: / (75) Kirkwood R.N., Culham E.G., Costigan P., Radiographic and non-invasive determination of the hip joint center location: effect on hip joint moments. Clin Biomech (Bristol, Avon), 1999, 14 (4), doi: /S (98) Stagni R., Leardini A., Cappozzo A., Grazia-Benedetti M., Cappello A., Effects of hip joint centre mislocation on gait analysis results. J Biomech, 2000, 33 (11), , doi: /S (00) Bell A.L., Brand R.A., Pedersen D.R., Prediction of hip joint centre location from external landmarks. Hum Mov Sci, 1989, 8 (1), 3 16, doi: / (89) Cappozzo A., Gait analysis methodology. Hum Mov Sci, 1984, 3 (1), 27 50, doi: / (84) Leardini A., Cappozzo A., Catani F., Toksvig-Larsen S., Petitto A., Sforza V. et al., Validation of a functional method for the estimation of hip joint centre location. J Biomech, 1999, 32 (1), , doi: /S (98) Weinhandl J.T., O Connor K.M., Assessment of a greater trochanter-based method of locating the hip joint center. J Biomech, 2010, 43 (13), , doi: /j. jbiomech Sinclair J., Taylor P.J., Edmundson C.J., Brooks D., Hobbs S.J., The influence of two different hip joint centre identification techniques on 3-D hip joint kinematics. In: International Convention on Science, Education and Medicine in Sport annual conference July Glasgow 2012, Cappozzo A., Cappello A., Croce U., Pensalfini F., Surface-marker cluster design criteria for 3-D bone movement reconstruction. IEEE Trans Biomed Eng, 1997, 44 (12), , doi: / Sinclair J., Taylor P.J., Edmundson C.J., Brooks D., Hobbs S.J., Influence of the helical and six available Cardan sequences on 3-D ankle joint kinematic parameters. Sports Biomech, 2012, 11 (3), , doi: / Eng J.J., Winter D.A., Kinetic analysis of the lower limbs during walking: What information can be gained from a three dimensional model? J Biomech, 1995, 28 (6), , doi: / (94)00124-M. 14. Bowsher K.A., Vaughan C.L., Effect of foot-progression angle on hip joint moments during gait. J Biomech, 1995, 28 (6), doi: / (94)00123-L. 15. Cohen J., Statistical power analysis for the behavioral sciences. Academic Press, New York Sinclair J., Bottoms L., Taylor K., Greenhalgh A., Tibial shock measured during the fencing lunge: the influence of footwear. Sports Biomech, 2010, 6 (2), 65 71, doi: / Mizuno Y., Kumagai M., Mattessich S.M., Elias J.J., Ramrattan N., Cosgarea A.J. et al., Q-angle influences tibiofemoral and patellofemoral kinematics. J Orthop Res, 2001, 19 (5), , doi: /S (01) Horton M.G., Hall T.L., Quadriceps femoris muscle angle: normal values and relationships with gender and selected skeletal measures. Phys Ther, 1989, 69 (11),

47 J. Sinclair, L. Bottoms, Effect of hip joint centre on lunge 19. Koga H., Nakamae A., Shima Y., Iwasa J., Myklebust G., Engebretsen L. et al., Mechanisms for noncontact anterior cruciate ligament injuries: knee joint kinematics in 10 injury situations from female team handball and basketball. Am J Sports Med, 2010, 38 (11), , doi: / Richards J., Forces moments and muscles. In: Richards J. (ed.), Biomechanics in clinic and research. Churchill Livingston Elsevier, USA 2008, Siu D.W., Cooke T.D.V., Broekhoven L.D., Lam M., Fisher B., Saunders G. et al., A standardized technique for lower limb radiography: practice, application, and error analysis. Invest Radiol, 1991, 26 (1), Paper received by the Editors: September 11, 2012 Paper accepted for publication: June 14, 2013 Correspondence address Jonathan Sinclair Division of Sport, Exercise and Nutritional Sciences School of Sport Tourism and Outdoors University of Central Lancashire Preston, Lancashire PR1 2HE, United Kingdom JKSinclair@uclan.ac.uk 237

48 2013, vol. 14 (3), The effects of a perturbation-based balance training on the reactive neuromuscular control in community- -dwelling older women: a randomized controlled trial doi: /humo Luciano Pavan Rossi 1, 4 *, Rafael Pereira 2, Michelle Brandalize 3, Anna Raquel Silveira Gomes 4 1 State University of Centro-Oeste, Guarapuava, Paraná, Brazil 2 State University of Southwest Bahia, Jequié, Bahia, Brazil 3 Guairacá Faculty, Guarapuava, Paraná. Brazil 4 Federal University of Paraná, Curitiba, Paraná, Brazil Abstract Purpose. The purpose of this study was to evaluate the effects of short-term perturbation-based balance training and a detraining period on postural control in older adults. Methods. A group of healthy older women were recruited and divided into two groups: an exercise group (EG, n = 21, age = 67.0 ± 2.0 y) that performed balance-based exercises three times a week over a sixweek period and a control group (CG, n = 20, age = 67.9 ± 3.1 y). Center-of-pressure displacement (CoP) and electromyographic data (EMG onset, time-to-peak and amplitude) were assessed during forward and backward perturbations for six leg muscles. All variables were analyzed before the training program began, at its end, and after a six-week period of detraining. A mixed ANOVA model was used to analyze the within- and between-subject results. Results. A decrease in backward CoP displacement, EMG onset and time-to-peak of the ankle muscles, especially the tibialis anterior (TA) and gastrocnemius (MG), was observed. Improvement in muscle EMG amplitude for the ankle muscles (TA, MG and Soleus SO) at the early phase (0 200 ms) of the perturbation test, with the SO also showing an increase in amplitude at the intermediate phase ( ms). After the detraining period, only the TA muscle maintained an improvement in reaction time. Conclusions. Perturbation-based balance training improved neuromuscular responses such as muscle reaction time and ankle muscle activation and consequently aided the body s ability to maintain correct center of pressure, although after a period of detraining this gain was not maintained for most of the assessed variables. Key words: elderly, exercise, postural balance, electromyography, reaction time Introduction Senescence is associated with a general deterioration of many biological systems, mainly in the locomotor system. The deterioration of postural control and the decreased ability to preserve body balance during unpredictable perturbations, such as those that occur during activities of daily living, may contribute to an increase in the incidence of falls among elderly persons [1, 2]. Changes in the sensory and motor systems are also suspected to play a role in the decreased ability to maintain adequate postural adjustment when standing upright [3]. In an attempt to maintain postural control during unpredictable perturbations, excessive movement of the center of mass can be quickly corrected by generating muscle torques at the ankles, hips, and other joints, whereby a stabilizing effect can be achieved by rapidly moving the base of support [4]. However, elderly people have greater difficulty in detecting the direction and magnitude of such disturbances, which limits the gene ration of appropriate neuromotor action that would be quick and forceful enough to counteract the effects of such perturbations [5]. * Corresponding author. Older adults show larger horizontal center-of-pressure displacement and require more time to reverse the direction of this displacement than younger adults when exposed to unpredictable balance perturbations [3, 6]. This could be explained, at least in part, by the increased time to activate and reach peak muscle activation in response to postural changes [1], as response time has been shown to play an import role in the recovery from a loss of balance. This slowed response causes greater acceleration during a fall, therefore demanding a greater force to counteract the fall [7]. In addition, Van den Bogert [8], through the use of an inverted pendulum model, showed that variations in response time are more important than variations in walking velocity when determining the successful recovery of avoiding a fall after tripping. Understanding the changes in the postural control of elderly individuals is important to help prevent the loss, reduction, or reversal of specific age-related impairments and help improve reactive postural control [9]. Several systematic reviews and clinical trials have recommended the use of exercise programs that include a balance-training component to improve body balance [10] to prevent falls in elderly adults [11 13]. However, current exercise programs are frequently criticized for a lack of standardization of specific training protocol such as type of exercise and duration [13], and those 238

49 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women studies who did perform analysis of such programs did not involve testing a perturbation situation [10, 13]. A perturbation-based balance training program that is arbitrarily administered (variations in time, magnitude, and direction) works against the central nervous system s ability to predict the specific characteristics of perturbation or its ability to use such information to counteract the effects of a loss of balance [12]. The introduction of new dynamic postural control strategies might therefore help better restore balance against abrupt postural disorders [9, 14, 15] and could possibly be used in the future to predict falls and improve balance in the elderly. Unstable devices such as the mini-trampoline have been used to improve the elderly s abilities to recover their balance during forward falls [16]. However, the effects of perturbation-based balance training, such as in a circuit set that includes the use of such unstable devices, on reactive neuromuscular responses and center-of-pressure displacement in the elderly have not yet been studied. Thus, the aim of this study was to conduct a randomized clinical trial to verify the effects of a six-week perturbation-based balance training program followed by a six-week period of detraining in a group of healthy elderly women by measuring electromyographic (onset, time-to-peak, and mean amplitude of EMG signals at 0 200, and ms) and stabilometric (forward and backward center-of-pressure displacement) variables in situations with unpredictable perturbation. Our hypothesis was that a regularly performed six-week (three times per week) perturbation-based balance training program may be sufficient in ameliorating reactive postural control and maintain improvements in balance control after a detraining period of six weeks. Material and methods The study population consisted of elderly women living in a local community who were invited to participate in the study by leaflet or word of mouth. Seventythree women attended the initial meeting, of whom 27 were excluded after the following exclusion criteria were applied: pain in the lower extremities; having had orthopedic surgery; history of fractures within the past year; inability to walk unaided; occurrence of neurological diseases; diagnosed acute inflammatory disease (due to possible interference in performing the training exercises), uncontrolled mellitus diabetics or arterial hypertension; use of medications that can affect balance; or featuring cognitive impairment based on a score of < 24 on the mini-mental state examination. The remaining 46 women were selected for inclusion. All were community-dwelling individuals, of mixed race and social class, aged between 65 and 80 years old, and classified as active (score > 53) according to the Brazilian version of the Human Activity Profile criteria [17]. The study was approved by the Ethics Committee of the State University of Centro-Oeste (#200/2011) and was registered at The Brazilian Clinical Trials Registry (#RBR6HP5H9). The volunteers were randomly divided into two groups: a Control Group (CG, n = 20, age = 67.9 ± 3.1 y, BMI = 28.5 ± 3.2 kg m 2 ) and Exercise Group (EG, n = 21, age = 67.0 ± 2.0 y, BMI = 27.6 ± 2.4 kg m 2 ). In order to reduce the chance of having unbalanced groups, the participants were classified in quartiles based on the Timed-up & Go test (TUG) [18]. The participants of each quartile were randomly assigned to either the EG (TUG = 10.2 ± 1.3 s) or CG (TUG = 10.1 ± 1.8 s). An independent t test (p > 0.05) found no differences between groups for age, BMI, and TUG scores. The study design is shown in Figure 1. All participants were evaluated by use of a perturbation test based on a sliding apparatus constructed specially for this study, which was similar to the one described by Freitas et al. [1]. Data were collected three times, before the training program began (pre-training), after completing six weeks of balance training (post-training), and after a six-week detraining (post-detraining). The purpose of the specially-built apparatus (see Fig. 2) was to produce a sudden perturbation as a closed kinetic chain (e.g., trip and slip) by instigating forward and backward balance loss. The apparatus consisted of a sliding steel platform (45 cm 45 cm 5 cm) built so as to allow the measurement of center-of-pressure displacement during postural change and to collect electromyographic data in accordance with previous studies [4, 7]. To capture center-of-pressure displacement during perturbation, a baropodometric platform was placed on top of the sliding platform. The platform moved either forwards or backwards at a distance of 12 cm in a time frame of 0.47 s at a mean velocity of 24.8 cm/s and mean acceleration of 54.7 cm/s 2. The force generated to move the platform (abrupt perturbation) was generated by dropping a weight of 5 kg from a height of 25 cm that was connected to the platform by a steel cable. During the perturbation test, participants were instructed to stand on the baropodometric platform with their feet parallel and 5 cm apart, their arms relaxed close to their sides, head upright, and eyes open. A strain gauge was used to measure the initial moment of the platform s displacement in order to determine the start of reaction time. To avoid the risk of falling the participants were secured by an upper-body safety harness [12]. To evaluate for intra-observer variability, ten measurements made with the strain gauge (peak strength) and platform speed on two separate days three days apart were collected. The Intra-class Correlation Coefficient (ICC) and a confidence interval (CI) of 95% were adopted. Good repeatability for peak strength with the strain gauge was found (ICC = 0.785; 95% CI 0.37, 0.94) and moderate to good repeatability (ICC = 0.73, 95% CI 0.24, 0.92) for sliding platform speed. ICC and IC analysis were performed using SPSS ver (IBM, USA). To assess concomitant electromyographic data, six pairs of bipolar surface electrodes were placed on the participants dominant side s rectus femoris (RF), vastus 239

50 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women Figure 1. Flow diagram of the study design SC security cable BP baropodometric platform SH safety harness SP sliding platform EMG electrodes C steel cable SG strain gauge W 5 kg weight Figure 2. Experimental perturbation-based apparatus using a sliding platform medialis oblique (VMO), tibialis anterior (TA), semitendinosus (ST), medial head of gastrocnemius (MG), and soleus (SO) muscles (leg preference was chosen by asking the participants to climb up a 40 cm platform; the leading leg instinctively chosen by the participants was considered the dominant leg). Capture of EMG signals for the RF, VMO and TA muscles was performed during forward displacement of the platform, while the ST, MG and SO muscles were analyzed when the platform moved backwards. EMG signals were recorded at 2000 Hz amplified with a gain of 1000x, then band-pass filtered ( Hz) and converted from analog to digital by a 16 bit A/D converter. The EMG signals were full-wave rectified and low-pass filtered by a 3 rd order zero-lag Butterworth filter. EMG data includes measurements of EMG onset (representing how fast a muscle is activated after the introduction of the perturbation), EMG time-to-peak (representing how quickly a muscle reaches its maximum level of activation), and the amplitude (intensity) of the EMG signal. These variables provided important information on muscle function and force production. Statistical analysis was performed using a customized version of Matlab (Mathworks, USA) to process and analyze the EMG signal data. EMG onset for each muscle was automatically determined when the intensity of muscle activity crossed 7% of the electromyographic signal peak after perturbation. All EMG onsets were visually confirmed by the experimenter with graphs generated by 240

51 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women the Matlab program. EMG time-to-peak was computed as the difference between the instant that the muscle reached maximum level of activation and EMG onset time. The amplitude of EMG activity for each muscle was estimated by calculating the root mean square (RMS) at three time intervals: ms (early phase), ms (intermediate phase), and ms (late phase) with respect to EMG muscle onset. The exercise training program consisted of sessions lasting 40 min held three times per week [13] for a period of six consecutive weeks [13, 19, 20]. They were conducted in groups of 12 and supervised by a physiotherapist. The first 10 min consisted of a warm-up performed on a stationary bicycle at 40 60% of heart rate reserve. The remaining 30 min consisted of exercises designed specifically for balance training with the use of balance devices simulating unstable ground [20, 21]. During each training session, six unstable devices were used: a proprioceptive disk [21], a rocker, a balance board [20, 22], a Bosu ball (Bosu, USA), an inverted Bosu ball, and a mini-trampoline [16]. During all balance exercises the participants were instructed to stand upright, look forward, and maintain a knee flexion of 15 degrees. The types of training exercises performed were based on the suggestions of researchers [19, 20], beginning with bipodal exercises for the first three weeks which advanced to unipodal exercises for the remaining three weeks. The exercise protocol consisted of performing four 1-min repetitions [19, 22] on each device (completing the circuit) with 1 min rest between each repetition. For statistical analysis, distributions of the stabilometric data and EMG onset, time-to-peak, mean amplitude signals were tested for normality using the Shapiro- Wilk test while Levene s test was used to determine homogeneity. Two-way ANOVA (2 groups 3 measures) was used to compare the groups versus their results. When the relationship was determined to be statistically significant, one-way ANOVA with repeated measures was used. For the mean amplitude of the EMG signals, the Friedman test was used to compare measures at pretraining (PRE) post-training (POST) 6 weeks after training (POST6). When statistical significance was observed, the Wilcoxon test with Bonferroni correction ( /number of comparisons) was used as a post-hoc test. Comparisons between groups were performed with the Mann-Whitney U test. In addition, the Minimal Detectable Change (MDC) was adopted in order to detect the smallest amount of change by a measure that corresponds to a noticeable change in ability, calculated by the equation MDC = 1.96 * 2 * SEM, where SEM (Standard Error of Measurement) = standard deviation * (1 ICC). A significance level of p < 0.05 was adopted for all statistical procedures, which were performed using SPSS ver (IBM, USA). Results Stabilometric measurement of center-of-pressure (CoP) displacement found backward CoP displacement having a significant group measure (F 2,78 = 9.17; p < ) interaction. The backward CoP displacement measured after the training program was significantly less than measures tested at pre-training (p < ) and post-detraining (p = 0.003). Additionally, the exercise group s (EG) backward CoP displacement was significantly smaller than the control group s (CG) before beginning the training program (F 1,39 = 4.60, p = 0.038) but not after the detraining period (F 1,39 = 0.46, p = 0.50). In contrast to the results on backward displacement, forward CoP displacement did not show significant group measure (F 2,78 = 3.01; p = 0.056) interaction, although repeated measures performed separately for each group showed a reduction in the CoP for the EG (F 2,40 = 5.28, p = 0.009) after completing the training program (Fig. 3). Analysis on the collected electromyographic data found that EMG onset for RF, VMO and ST after the balance training program did not show significant differences or interaction for measures and groups (p > 0.05, Exercise Group (EG) and Control Group (CG) * significantly different from PRE of the same group (p < 0.05) # significantly different from POST of the CG (p < 0.05) Figure 3. Backward (A) and forward (B) CoP displacement measured at intervals before (PRE), after (POS), and six weeks after (POS6) the balance training program 241

52 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women * significantly different from PRE measures of the same group (p < 0.05), significantly different from PRE and POS of the same group (p < 0.05) # significantly different from POS of the CG (p < 0.05) Figure 4. EMG onset of rectus femoris (A), vastus medialis oblique (B), semitendinosus (C), tibialis anterior (D), medial head of gastrocnemius (E) and soleus (F) muscles after sudden perturbation Table 1. Mean ± SD of stabilometric and EMG time variables (EMG onset and time-to-peak) measured at intervals before (PRE), after (POST), and six weeks after (POST6) the balance training program showing Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC) for each variable Group Variable PRE POST POST6 ICC SEM MDC Exercise group Control group Stabilometry (cm) Onset (ms) Time-to-peak (ms) Stabilometry (cm) Onset (ms) Time-to-peak (ms) Forward displacement ± ± 3.13 a ± 3.44 b Backward displacement ± ± 2.37 a,c ± 2.50 b RF ± ± ± VMO ± ± ± ST ± ± ± TA ± ± a,c ± d MG ± ± a ± SO ± ± a,b ± RF ± ± ± VMO ± ± ± ST ± ± ± TA ± ± a,c ± d MG ± ± a,b,c ± d SO ± ± ± Forward displacement ± ± ± Backward displacement ± ± ± RF ± ± ± VMO ± ± ± ST ± ± ± TA ± ± ± MG ± ± ± SO ± ± ± RF ± ± ± VMO ± ± ± ST ± ± ± TA ± ± ± MG ± ± ± SO ± ± ± a significantly different (repeated measures ANOVA/post-hoc Bonferroni, b significantly different between POST POST6 of the same group (p < 0.05), c significantly different from POST of the CG (p < 0.05), d significantly different from POST6 of the CG (p < 0.05), p < 0.05) between PRE POST of the same group (p < 0.05) 242

53 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women Table 2. Mean ± SD of EMG amplitude at early (0 200 ms) and intermediate ( ms) phase of activation measured before (PRE), after (POST), and six weeks after (POST6) the balance training program Group EMG amplitude PRE POST POST6 Mean ± SD RF ± ± ± VMO ± ± ± ms ST ± ± ± TA ± ± a, c ± b MG ± ± a, c ± b SO ± ± a, c ± b RF ± ± ± VMO ± ± ± ms ST ± ± ± 9.66 TA ± ± ± MG ± ± a ± SO ± ± a, c ± b RF ± ± ± VMO ± ± ± ms ST ± ± ± TA ± ± ± MG ± ± ± SO ± ± ± RF ± ± ± VMO ± ± ± ms ST ± ± ± 8.68 TA ± ± ± MG ± ± ± SO ± ± ± a significantly different in PRE POST, b POST POST6 (Friedman test, c significantly different (Mann Whitney U test, p < 0.05) between means of groups in POST, p < 0.05/Wilcoxon as post hoc /3) Exercise group Control group see Fig. 4A C). In contrast, EMG onset for TA post-training showed a significant group measure interaction (F 2,78 = 6.52; p = 0.002) (see Fig. 4D). Further analysis indicated that EMG onset for the TA was reduced after the training period only for the EG (p < 0.05) and that this reduction continued to be present even after the 6-week detraining period (p < 0.05). The EG group also showed earlier EMG onset times compared with the CG at measurement period after the training (F 1,39 = 7.525, p = 0.009) and detraining period (F 1,39 = 4.67, p = 0.03). As observed with the TA muscle, EMG onset for the MG and SO muscles post-training found that the EG showed significant differences among the measures (MG: F 1.40, = 6.04, p = 0.013, SO: F 2.40 = 20.61, p = 0.000, see Fig. 4E F). Both muscles exhibited a significant reduction in EMG onset time after undergoing balance training, although this reduction was sustained after the six-week detraining period only for the MG (p < 0.05). There was no significant group measure interaction for both MG (F 1.55, =1.80, p = 0.18) and SO (F 2.78 =2.43, p = 0.09) and no difference between the CG and EG for all analyses (p > 0.05). Similar to what was observed with the time of EMG onset, EMG time-to-peak after training for RF, VMO, and ST did not show significant differences or interaction for measures and groups (p > 0.05), while the TA showed a significant group measure interaction (F 1.74, = 10.30, p = ) (see Tab. 1) with differences found only for the EG (F 1.39 = 20.61, p = 0.000), which indicated that EMG time-to-peak for the TA was reduced after training only for the EG (p < 0.05) and that this reduction was kept even after the detraining period (p < 0.05). These values were 16% lower for the EG at posttraining and 13% lower at post-detraining than the CG (p < 0.05). The EMG time-to-peak for the GM post-training showed a significant difference between measures (F 2,78 = 14.29; p < 0.001) and significant group measure interaction (F 2,78 = 20.73; p < 0.001). The GM muscle exhibited a significant reduction in EMG time-to-peak post-training and post-detraining (p < 0.05) and these values were lower than the CG s only at post-training (p < 0.05). The EMG amplitude at the early phase of activation (0 200 ms) found significant differences between measures for the EG for the TA, MG and SO muscles as identified by the Friedman test (p < for all muscles, see Tab. 2). Post hoc analysis indicated an increase in EMG amplitude post-training for the MG, SO and TA muscles at 13%, 17%, and 17%, respectively (p < ), although only the TA muscle sustained this significant increase at post-detraining (POST POST6, p > 0.05). 243

54 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women EMG amplitude at the intermediate phase ( ms) showed an increase in muscle activation for the TA, MG, and SO muscles (p < 0.05) for the EG at posttraining (TA: 10%, p = 0.005; MG: 8%, p = 0.002; and SO: 10%, p = 0.001). However, only the TA and MG muscles sustained this increase after the detraining period (POST POST6, p > 0.05). Comparison between groups showed greater amplitude for the EG than the CG posttraining for muscles: TA (17%, p = 0.04), MG (13%, p = 0.007), and SO (19%, p = 0.000) at the early phase and for SO (10%, p = 0.047) at the intermediate phase. EMG amplitude at the late phase ( ms) had no statistically significant differences within- and between-groups for all of the evaluated muscles (p > 0.05). No clinical changes were observed in the analyzed variables when tested by the Minimal Detectable Change (MDC), finding that the balance training program did not generate statistically significant differences in this regard. Discussion The purpose of the present study was to investigate the role of perturbation-based balance training on postural control. Two hypotheses were formulated: (1) would elderly women show an improvement in the reactive neuromuscular response of the lower limb muscles and a decrease in center-of-pressure (CoP) displacement after completing a six week perturbation-based balance training course based on a circuit set of unstable devices and (2) would these changes still be present following a sixweek period of detraining? It was observed that CoP displacement was reduced following the balance training program, although significant differences were observed only for backward displacement when compared with control group. Nonetheless, this suggests an improvement in balance control as it would help prevent excessive horizontal displacement of center-of-mass (CM). Indeed, the reduction of CoP displacement is the main goal of postural response immediately after perturbation so as to avoid a fall [1]. This was also confirmed in the present study by the decreased temporal muscle activity and increased EMG activity of the ankle muscles after completing the balance training program, which may have prevented excessive CoP displacement through quick and appropriate muscle activation [1, 4]. Furthermore, the exercise group (EG) showed faster reaction times in the anterior and posterior ankle muscles after completing the balance training program, in particular with the tibialis anterior (TA), which maintained this reduction even after the detraining period. The results were greater for TA possibly due to more frequent activation by unstable surfaces such as when standing on a mini-trampoline or balance board [23], equipment used in this study s training regime. Regarding EMG time-to-peak, both TA and MG had a 17% average reduction in the EG post-training compared with the CG, although this improvement was maintained post-detraining only for the TA muscle. Nonetheless, this indicates that improvement in muscle reactivity can be achieved in the elderly with short-term balance training (six weeks). This outcome shows how quickly the muscles of older adults can reach their maximum level of activation and generate torque after perturbation [1]. This was additionally confirmed by other studies, which found that maximum TA strength is preserved in the sixth decade of life [24] and that older adults can generate ankle joint torque similar to that of younger adults after platform translation [25]. In addition, early and appropriate muscle activation diminishes the chances of excessive CM displacement and can help obtain quicker time-to-peak intensity [1], which is particularly important in the elderly when the central and peripheral nervous systems suffer age-related degradation. Demyelination, loss of axonal fibers, degeneration of fast fibers motor neurons are all common problems that can lead to a decrease in nerve conduction velocity [26] and peak activation, especially after the fifth decade of life [1]. Furthermore, slowed motor time reaction is representative of reduced excitation contraction coupling, including slowed calcium release or reuptake from the sarcoplasmic reticulum and decreased activity of metabolic enzymes such as creatine kinase and actomyosin ATPase [27, 28]. Several studies had shown changes in the reaction time of the peroneus longus and tibialis anterior muscles with balance training in young adults [21, 29]. Our study showed that both EMG onset and EMG time-to-peak can also be trained and improved in the elderly with balance training. For older individuals, the improvement of these variables can help prevent a fall as a fast muscular reactive response is essential in maintaining balance during a slip or trip. Concerning the results on EMG amplitude, this study showed improvement among the distal muscles after balance training. However, this improvement was expressive only in the EMG amplitude at the early phase of activation (0 200 ms), which may possibly be the result of the unstable apparatuses used in the training exercises that may have stimulated a faster muscle reactive response. According to Maki et al. [14], compensatory reactive responses are decisive reactions for preventing falls. These reactions are much more rapid than volitional limb movements and are effectual in controlling the CM motion generated by sudden, unpredictable perturbations. Our results confirm, at least in part, the first hypothesis on the effectiveness of a balance training exercise regime in reducing CoP motion, EMG time-to-peak, and onset and increasing muscle activity (EMG amplitude). However, these improved EMG parameters (EMG onset, time-to-peak, and amplitude) were found only in the distal muscles, which may have resulted from the use of unstable surface training that would more actively recruit the ankle muscles, especially the TA [23]. 244

55 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women It is known that older individuals decrease their use of ankle-based strategies and prefer hip postural strategies to remain upright [30], and this may be related to the slowness in stabilizing the ankles in perturbation tests that simulate a fall [4] and to delayed muscle activation [1]. Therefore, the neuromuscular enhancement of the distal muscles obtained here may be important in improving the postural control in older adults. For the second hypothesis, on the effects of detraining, we found that the balance training exercise regime was not able to maintain all improvements (except for the TA muscle, which maintained improved EMG onset and time-to-peak levels), which may be related to the continuously debilitating effects of senescence. The deterioration observed among the majority of the studied electromyography variables after the detraining period, particularly in the MG and SO muscles, might also explain why the improvement in CoP displacement was not retained. Thus, six weeks of no exercise can generate significant reductions in muscle reactive capacity and postural control, indicating that a progressive loss of postural and muscle capacity can occur in the elderly in a relatively short timeframe [2]. This highlights the need for the elderly to participate in regularly-held exercise programs (i.e., without long pauses) so as to sustain the benefits obtained after completing an initial balance training program. There were some limitations in the study that need to be addressed in future research. First, the training regime adopted in the present study used static balance training. The use of dynamic balance training might have generated more indicative results that may have also been maintained after the detraining period. The evaluation of a perturbation while walking would have served as a more pertinent guide as most falls occur during walking [15]. Another limitation was the absence of kinematic analysis, which could have shown an improvement in other balance strategies other than neuromuscular. It is also suggested that future studies consider the evaluation of mediolateral displacement and those muscles corresponding to this movement direction as well as perform weekly evaluations after the detraining period in order to analyze exactly when and why the losses arising from detraining happen. Conclusions Disturbance-based balance training with the use of multidirectional unstable devices improved ankle muscle reactive capability (EMG onset and EMG time-to-peak). This was best demonstrated by EMG amplitude at the early phase of activation during the perturbation test especially for the TA muscle and at the intermediate phase for the MG and SO. However, no changes among the analyzed variables were observed for the hip and knee muscles or for EMG amplitudes of all muscles in the late phase of activation in response to the disturbance. The improvement in muscle reactive capability may explain better postural control during the perturbation test. However, a six-week period of detraining was enough to reverse the observed improvements in postural control and reactive muscular response, except for the increase in temporal activation of the tibialis anterior muscle. Acknowledgements This study received financial support from the Araucária Foundation in Brazil (#16423). In addition, A. Gomes is a fellowship recipient at Conselho Nacional de Desenvolvimento Científico e Tecnológico (under grant #308696/2012-3). 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56 L.P. Rossi, R. Pereira, M. Brandalize, A.R.S. Gomes, Balance training in older women Society clinical practice guideline for prevention of falls in older persons. J Am Geriatr Soc, 2011, 59 (1), , doi: /j x. 12. Mansfield A., Peters A.L., Liu B.A., Maki B.E., Effect of a perturbation-based balance training program on compensatory stepping and grasping reactions in older adults: A randomized controlled trial. Phys Ther, 2010, 90 (4), , doi: /ptj Sherrington C., Whitney J.C., Lord S.R., Herbert R.D., Cumming R.G., Close J.C.T., Effective exercise for the prevention of falls: a systematic review and meta-analysis. J Am Geriatr Soc, 2008, 56 (12), , doi: / j x. 14. Maki B.E., McIlroy W.E., Fernie G.R., Change-in-support reactions for balance recovery. Eng Med Biology Mag, 2003, 22 (2), 20 26, doi: /MEMB Pijnappels M., Reeves N.D., Maganaris C.N., Van Dieen J.H., Tripping without falling; lower limb strength, a limitation for balance recovery and a target for training in the elderly. J Electromyogr Kinesiol, 2008, 18 (2), , doi /j.jelekin Aragão F.A., Karamanidis K., Vaz M.A., Arampatzis A., Mini-trampoline exercise related to mechanisms of dynamic stability improves the ability to regain balance in elderly. J Electromyogr Kinesiol, 2011, 21 (3), , doi: /j.jelekin Souza A.C., Magalhães L.C., Teixeira-Salmela L.F., Crosscultural adaptation and analysis of the psychometric properties in the Brazilian version of the Human Activity Profile [in Portugues]. Cad Saúde Pública, 2006, 22 (12), , doi: /S X Podsiadlo D., Richardson S., The timed Up & Go : a test of basic functional mobility for frail elderly persons. J Am Geriatr Soc, 1991, 39, (2) Cardinale M., Newton R., Nosaka K., Strength and conditioning: Biological principles and practical applications. Wiley-Blackwell, Chichester Cooper R.L., Taylor N.F., Feller J.A., A randomised controlled trial of proprioceptive and balance training after surgical reconstruction of the anterior cruciate ligament. Res Sports Med, 2005, 13 (3), , doi: / Osborne M.D., Chou L.-S., Laskowski E.R., Smith J., Kaufman K.R., The effect of ankle disk training on muscle reaction time in subjects with a history of ankle sprain. Am J Sports Med, 2001, 29 (5), Verhagen E.A.L.M., van Tulder M., van der Beek A.J., Bouter L.M., van Mechelen W., An economic evaluation of a proprioceptive balance board training programme for the prevention of ankle sprains in volleyball. Br J Sports Med, 2005, 39 (2), , doi: /bjsm Ferreira L.A.B., Pereira W.M., Rossi L.P., Kerpers I.I, Paula A.R., Oliveira C.S., Analysis of electromyographic activity of ankle muscles on stable and unstable surfaces with eyes open and closed. J Bodyw Mov Ther, 2011, 15 (4), , doi: /j.jbmt McNeil C.J., Vandervoort A.A., Rice C.L., Peripheral impairments cause a progressive age-related loss of strength and velocity-dependent power in the dorsiflexors. J Appl Physiol, 2007, 102 (5), , doi: /japplphysiol Gu M.-J., Schultz A.B., Shepard N.T., Alexander N.B., Postural control in young and elderly adults when stance is perturbed: dynamics. J Biomech, 1996, 29 (3), , doi: / (95) Rivner M.H., Swift T.R., Malik K., Influence of age and height on nerve conduction. Muscle Nerve, 2001, 24 (9), , doi: /mus Prochniewicz E., Thomas D.D., Thompson L.V., Age-related decline in actomyosin function. J Gerontol A Biol Sci Med Sci, 2005, 60 (4), , doi: /gerona/ Kaczor J.J., Ziolkowski W., Antosiewicz J., Hac S., Tarnopolsky M.A., Popinigis J., The effect of aging on anaerobic and aerobic enzyme activities in human skeletal muscle. J Gerontol A Biol Sci Med Sci, 2006, 61 (4), Akhbari B., Takamjani I.E., Salavati M., Sanjari M.A., A 4-week biodex stability exercise program improved ankle musculature onset, peak latency and balance measures in functionally unstable ankles. Phys Ther Sport, 2007, 8 (3), , doi: /j.ptsp Amiridis I.G., Hatzitaki V., Arabatzi F., Age-induced modifications of static postural control in humans. Neurosci Lett, 2003, 350 (3), , doi: /S (03) Paper received by the Editor: May 13, 2013 Paper accepted for publication: June 19, 2013 Correspondence address Luciano Pavan Rossi R. Camargo Varela de Sá, 03 Vila Carli, Guarapuava PR, Brazil lucianofisioo@yahoo.com.br 246

57 2013, vol. 14 (3), Changes in breathing pattern and cycling efficiency as a result of training with added respiratory dead space volume doi: /humo Paulina Hebisz *, Rafał Hebisz, Marek Zatoń University School of Physical Education, Wrocław, Poland Abstract Purpose. The aim of this study was to evaluate the impact of training with added respiratory dead space volume (ARDSV) on changes in a breathing pattern and cycling efficiency. Methods. Twenty road cyclists were equally divided into an experimental (E) and control (C) group. All of them were involved in a training program that included endurance training (at moderate intensity) and interval training (at maximal intensity). During semi-weekly endurance training, ARDSV (1000cm 3 tube) was introduced in the experimental group. Respiratory parameters, including, among others, oxygen uptake (VO 2 ), carbon dioxide excretion (VCO 2 ), end-tidal partial pressure of carbon dioxide (PETCO 2 ), pulmonary ventilation (VE), tidal volume (TV) and total work done during the tests (W), were measured before and after the experiment by a progressive and continuous test. Results. Higher PETCO 2 and TV in both groups during the progressive and continuous tests were observed. VCO 2 increased in group E during continuous test, while for group C only in the first four minutes of the test. VO 2 and VE increased only in group E during submaximal and maximal exercise. Total work increased during the continuous test in both groups (significantly higher in group C than E). However, total work during the progressive test increased only in group E. Conclusions. Training with ARDSV improved exercise capacity at maximal effort and was associated with an increase in maximal oxygen uptake. On the other hand, this type of training lead to a decrease in cycling efficiency, reducing in effect the benefits associated with an increase in VO 2 max and reducing the ability to perform submaximal effort. Key words: added dead space, breathing pattern, cycling efficiency Introduction Cardiorespiratory efficiency is determined not only by the amount of oxygen supplied and used (maximal oxygen uptake) by the cardiovascular system but also by the efficiency in removing excess carbon dioxide [1, 2]. Some researchers believe that pulmonary ventilation may limit maximum performance during aerobic exercise. An increase in pulmonary ventilation during exercise allows the lungs to adjust the partial pressure of carbon dioxide in the arterial blood (P a CO 2 ), while the respiratory system helps control the hydrogen ion concentration in extracellular fluids [3]. However, reduced pulmonary ventilation causes an excessive increase of P a CO 2 in the blood during effort, where increased P a CO 2 levels are associated with greater blood and tissue acidosis [4]. A simultaneous increase in the partial pressure of carbon dioxide and decrease in blood ph is known to adversely affect muscle contractile properties and metabolism (by limiting enzyme activity), contributing to fatigue [2, 5]. As a result, high levels of P a CO 2 may indicate an insufficient increase in lung ventilation during effort and therefore limit the ability for maximal exercise. This may be due to mechanical respiratory constraints when reaching the upper limit of peak expiratory flow such insufficient respiratory muscle strength * Corresponding author. or even reduced chemoreceptor responsiveness. On the other hand, lower ventilation is also connected with decreased respiratory muscle work and may be the cause of decreasing blood flow to the respiratory muscles while increasing blood flow (by about 10%) to limb muscles. Such a mechanism may delay the onset of fatigue [4]. P a CO 2 can be measured noninvasively by sampling end-tidal partial pressure of carbon dioxide (P ET CO 2 ) [4, 6]. In most cases, the resting value of P ET CO 2 is slightly lower than PaCO 2 as decreased blood flow distribution in the lungs causes alveolar partial pressure of carbon dioxide to be lower than arterial partial pressure of carbon dioxide. However, P ET CO 2 is higher than P a CO 2 at submaximal or maximal effort, causing an increase in pulmonary blood flow and an increase in the delivery rate of carbon dioxide (CO 2 ) to the lungs [7, 8]. During effort, the difference between P a CO 2 and P ET CO 2 is mainly connected to respiratory rate, as the amount of expired CO 2 does not plateau. Therefore, for a given value of alveolar CO 2, P ET CO 2 is higher while the breathing frequency is lower [4]. According to Benallall and Busso [8], the difference between P a CO 2 and P ET CO 2 during exercise is influenced by both respiratory rate and tidal volume, where the greater the volume and respiration rate, the greater difference between these two measures. Additionally, a high value of P ET CO 2 may indicate high cardiovascular and ventilation efficiency. As a result, P ET CO 2 can serve as a marker that combines measures of performance and ventilation efficiency although it 247

58 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern cannot be regarded as an independent physiological variable [4]. In order to improve the efficiency of the gas exchange system and respiratory muscles, techniques such as specific inspiratory or expiratory muscle training or hyperpnoea training have been introduced [9 12]. Several authors reported that these methods improve breathing efficiency by increasing tidal volume while decreasing respiratory rhythm, resulting in a decrease in submaximal and an increase in maximal ventilation efficiency [9, 13, 14]. Furthermore, increased respiratory muscle strength following inspiratory training may contribute to a reduction in relative tension during submaximal exercise [14, 15]. A study by the present author also found that increasing dead space tidal volume as one form of respiratory training showed increases in pulmonary ventilation (VE) and respiratory tidal volume (TV) [16]. As it was not known whether the observed changes in the breathing process affected the efficiency of carbon dioxide removal, it was assumed that the increase in TV reduced P ET CO 2. Therefore, the aim of this study was to evaluate the impact of inspiratory training with added respiratory dead space volume on the breathing pattern, amount of exhaled carbon dioxide, and cycling efficiency. It was hypothesized that a change in breathing pattern, characterized by an increase in TV, would enhance work efficiency. Material and methods The study involved a 20-person group of road cyclists (all men) who were training together. The participants were evenly divided into an experimental (E) and control (C) group. Before the experiment, no statistically significant differences were noted between the experimental and control groups for mean values of age (E = 16.5 ± 0.5 y, C = 17.1 ± 0.7 y), body height (E = ± 3.8 cm, C = ± 4.4 cm), body mass (E = 70.4 ± 5.4 kg, C = 69.4 ± 7.2 kg), and maximal oxygen uptake (E = 64.4 ± 4.6 ml kg 1 min 1, C = 64.2 ± 4.7 ml kg 1 min 1 ) and work capacity (C = kj ± 41.8, C = ± 30.9 kj) during a progressive cycloergometer test. The study was approved by the Ethics Committee of the University School of Physical Education in Wroclaw, Poland and carried out in accordance with the Declaration of Helsinki. Additionally, all participants provided their written informed consent prior to testing. The experiment lasted 10 weeks during which the participants continued their existing training program that involved both aerobic and anaerobic cycling exercises. Three types of training were employed: (1) interval training consisting of 40-second repetitions at maximum intensity followed by six minutes of active recovery by exercising at a low intensity (50 60% maximum heart rate, HRmax), (2) high intensity interval training consisting of alternating exercise, where five minutes was performed at maximum intensity (95 100% HRmax) followed by fifteen minutes of medium-intensity exercise (65 70% HRmax), and (3) steady-state endurance training performed at 70 80% HRmax. Throughout each training session heart rate was monitored using a S810 heart rate monitor (Polar Sports, Finland). One type of training was employed once a day in the order provided and was then followed by a day of rest (i.e., first day interval training, second day high intensity interval training, third endurance training, a day of rest, and the next day again interval training, etc.). Each daily training session lasted 120 to 150 min. An apparatus increasing respiratory dead space was introduced in the experimental group. It consisted of a mask with a 1000 cm 3 tube worn over the mouth, forcing the inhalation of additional atmospheric air and thereby diluting the amount of exhaled air left in the mask and tube after each previous exhalation. This device was used only when the experimental group performed endurance training (therefore every fourth day during the 10-week period). The control group performed the same exercises as the experimental group but without any modification to their breathing pattern. Each participant was subjected to two physiological exercise tests prior and after the 10-week experiment. The first was a progressive test (incremental load) whereas the second was a continuous test performed at constant load. The tests were separated by an interval of one week with the progressive test being the first performed. During the tests, the experimental group did not use the apparatus for increasing respiratory dead space volume. The exercise tests were performed in laboratory conditions at the Exercise Laboratory at the University School of Physical Education in Wroclaw, Poland (PN-EN ISO 9001:2001 certified). The progressive test was performed on an Excalibur Sport cycle ergometer (Lode B.V., Netherlands), which was calibrated before each test session according to manufacturer s instructions. The test began at a load of 50 W, which was increased by 50 W every three minutes until the participant reached exhaustion. The cycle ergometer was controlled with a computer program that also registered instantaneous power, time, and speed and used these values to calculate the total work done during the test. Measurement of respiratory parameters began two minutes before the test and continued for five minutes after it was completed (after reaching exhaustion) and included: oxygen uptake (VO 2 ), carbon dioxide excretion (VCO 2 ), end-tidal partial pressure of carbon dioxide (P ET CO 2 ), pulmonary ventilation (VE), tidal volume (TV), and breathing frequency (BF). Measurement was performed by having the participants wear a mask connected to a Quark b² gas analyzer (Cosmed, Italy). The gas analyzer was calibrated before each test with a reference gas mixture of: CO 2 5%, O 2 16%, and N 2 79%. Oxygen consumption and oxygen consumption per kilogram of body mass were calculated for each participant 248

59 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern based on the composition of exhaled air and pulmonary ventilation. The continuous test was also performed on the Excalibur Sport cycle ergometer. A 10-minute warm-up on the ergometer preceded the test, during which the load for each participant was chosen so that heart rate did not exceed the anaerobic threshold (defined during the progressive test). The test was performed at a constant load of 85% of maximal aerobic power and continued until exhaustion. Maximal aerobic power was treated as the value at which maximum power was produced for at least 90 seconds during the progressive test. Exercise was performed at a self-selected pedal frequency. The computer program controlling the cycle ergometer modulated the workload in response to changes in pedaling frequency. The same respiratory parameters (VO 2, VCO 2, P ET CO 2, VE, TV, and BF) as in the progressive test were measured, following the exact same method. Oxygen consumption and oxygen consumption per kilogram of body mass was then calculated based on the composition of exhaled gas and pulmonary ventilation. Respiratory parameters (VO 2, VCO 2, P ET CO 2, VE, TV, and BF) were measured breath by breath. For later analysis, the parameters recorded during progressive test were averaged over 60-second periods. Measures of VCO 2 and P ET CO 2 during the continuous test were also averaged over 60-second periods, while VO 2, VE, TV, and BF were averaged in the steady-state phase (5 th 10 th minute of the test). In addition, a new variable was introduced measuring the percentage of maximal oxygen uptake (%VO 2 max) by the formula [VO 2 /VO 2 max 100%] and also calculated in the steady-state phase. Only data up to the 10-minute mark during the continuous test were analyzed as some of the participants were unable to continue exercising after this point. Statistical analysis was performed using Statistica ver (Statsoft, Poland). The arithmetic means and standard deviations of all measured parameters were calculated. Statistical significance was determined using Student s t test for all dependent variables. The level of statistical significance was set at p < Student s t test was also applied to determine the significance of differences between groups. Figure 1. P ET CO 2 measured for the experimental (E) and control (C) groups during the continuous test before and after the experiment Figure 2. P ET CO 2 measured for the experimental (E) and control (C) groups during the progressive test before and after the experiment Results End-tidal partial pressure of carbon dioxide (P ET CO 2 ) significantly increased during the continuous test in the experimental group between the 2 nd and 10 th minute of the test and in the control group at the 3 rd and 4 th minutes, and between the 6 th and 10 th minute of the test (Fig. 1). In the progressive test, P ET CO 2 values increased in both groups, with statistically significant differences in the experimental group observed at a load of W and in the control group at W (Fig. 2). The amount of carbon dioxide excreted (VCO 2 ) significantly increased upon conclusion of the experiment Figure 3. VCO 2 measured for the experimental (E) and control (C) groups during the continuous test before and after the experiment 249

60 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern Figure 4. VCO 2 measured for the experimental (E) and control (C) groups during the progressive test before and after the experiment Figure 5. VCO 2 measured at maximum load for the experimental (E) and control (C) groups during the progressive test before and after the experiment Table 1. Total work done and respiratory parameters for the experimental (E) and control (C) groups during the progressive test before and after the experiment Parameter Group E before Group E after Group C before Group C after ± SD ± SD ± SD ± SD W (kj) ± ± 46.10* ± ± VO 2 max (l/min) 4.48 ± ± 0.23* 4.38 ± ± 0.47 VO 2 max (ml/min/kg) 64.4 ± ± 2.9* 64.3 ± ± 5.1 VEmax (l/min) ± ± 18.6* ± ± 23.4 TVmax (l/breath) 2.93 ± ± 0.29* 2.89 ± ± 0.33* BFmax (breaths/min) ± ± ± ± 3.16* arithmetic mean, SD standard deviation, W total work done, VO 2 max maximal oxygen uptake VEmax maximal pulmonary ventilation, TVmax maximal tidal volume, BFmax maximal breathing frequency * difference before and after experiment at p > 0.05 Table 2. Total work done and averaged respiratory parameters (between the 5th and 10th minute) for the experimental (E) and control (C) groups during the continuous test before and after the experiment Parameter Group E before Group E after Group C before Group C after ± SD ± SD ± SD ± SD W (kj) ± ± 111.8* ± ± 121.4* VO 2 (l/min) 3.79 ± ± 0.24* 3.91 ± ± 0.30 %VO 2 max ± ± ± ± 6.82 VE (l/min) ± ± 11.73* ± ± TV (l/breath) 2.63 ± ± 0.25* 2.54 ± ± 0.25* BF (breaths/min) ± ± 5.54* ± ± 4.49* arithmetic mean, SD standard deviation, W total work done, VO 2 mean oxygen uptake %VO 2 max mean percentage of maximal oxygen uptake, VE mean pulmonary ventilation TV mean tidal volume, BF mean breathing frequency, * difference before and after experiment at p > 0.05 in each minute of the continuous test in the experimental group. In the control group, a significant increase was observed only between the 1 st and 4 th minute of the continuous test (Fig. 3). However, during the progressive test, VCO 2 significantly decreased at a load of 350 W and significantly increased at 400 W and also at maximum load (power) in the experimental group, while no statistically significant differences for VCO 2 were observed in the control group (Fig. 4 and 5). After the experiment, only the experimental group in the progressive test featured significantly increased values for total work done, maximal oxygen uptake, and maximal pulmonary ventilation. Maximal tidal volume (TVmax) was found to significantly increase in both 250

61 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern groups after the 10-week period, whereas maximal breathing frequency (BFmax) significantly decreased only in the control group (Tab. 1). The total work done in the continuous test was found to increase in both groups. In the experimental group, increased values were observed for pulmonary ventilation and tidal volume while breathing frequency decreased. The control group featured an increase in tidal volume with a decrease in breathing frequency (Tab. 2). Discussion A gradual rise in P ET CO 2 is frequently observed during exercise of increasing intensity, reaching its maximum value at the beginning of respiratory compensation for lactic acidosis after which it slightly decreases and continues to do so until maximum effort is ceased. Rarely has P ET CO 2 been observed to continue to increase until the cessation of exercise [7]. According to Yano et al. [17], the same can be seen during exercise performed at a constant intensity (70% of maximal oxygen uptake), with P ET CO 2 first increasing and then decreasing. Similarly, the present study also found an initial increase and then decrease in P ET CO 2 in both the progressive and continuous tests. These changes are associated with a buildup of carbon dioxide, whose concentration rises for a few minutes and then plateaus as exercise is continued or even decreases due to increased pulmonary ventilation [2, 17]. In a study on individuals with chronic heart failure, it was found that a reduction in maximal P ET CO 2 values was correlated with a decrease in maximal oxygen uptake during incremental exercise [7]. In the present study, measures of maximal P ET CO 2 during the progressive test were found to have increased after the 10-week period in both the experimental and control groups. However, significant increases in maximal oxygen uptake and total work were observed only in the experimental group. Thus, it is quite probable that other factors than P ET CO 2 contributed to the rise invo 2 max in the experimental group. It is believed, in the case of conditioned athletes, that the most important exogenous agent that improves VO 2 max is high-intensity training [18]. However, in our study where exercise intensity was monitored using heart rate monitors (i.e., they performed the same intensity training), no significant differences were found in the results between the experimental and control groups. Therefore, further studies are needed to help explain how training with added respiratory dead space volume increases exercise capacity at maximum aerobic effort. According to Bussotti et al. [4], individuals with very low exercise P ET CO 2 (and therefore likely low P a CO 2 ) have lower exercise efficiency, as evidenced by high submaximal oxygen uptake and also exercise acidosis levels. In such cases, the authors observed a specific breathing pattern characterized by high pulmonary ventilation due to increased breathing frequency, which provoked an increase in physiological dead space and the amount of work performed by the respiratory muscles. In the present study, P ET CO 2 measured during the continuous test increased in both groups, although the control group reached higher P ET CO 2 values than the experimental group after the 10-week period. The experimental group presented higher oxygen consumption and pulmonary ventilation levels during the test than before the experiment as well as higher values than those of the control group. These results indicate that training with added respiratory dead space volume caused deterioration in exercise efficiency and could have mitigated the economizing effects on their endurance training. However, increases in pulmonary ventilation are due to tidal volume and not to an increase in breathing frequency. High pulmonary ventilation with high tidal volume and low breathing frequency is considered to be desirable, as it reduces physiological dead space and is less taxing on the respiratory muscles [4]. Our results indicate that the control group performed more total work during the continuous test despite a smaller change in tidal volume. The gains, in view of the increases in the maximal respiratory parameters, the experimental group achieved in the progressive test were reduced in the continuous test probably due to a decrease in exercise efficiency. This is the most likely explanation why this group showed less dramatic improvements in the total work done than the control group. It also can be deemed that the change in the experimental group s breathing pattern did not lead to improved efficiency. Anderson et al. [19] believe that breathing characterized by a reduction in breathing frequency with a simultaneous increase in tidal volume, triggering an increase in pulmonary ventilation, results in a reduction in end-tidal carbon dioxide tension. These authors suggest that lower P ET CO 2 may indicate higher ventilation efficiency. Then again, it is necessary to overcome the elastic forces of the lungs and chest wall, hence the increase in tidal volume above critical volume is associated with increased respiratory function [20]. This may be the reason explaining the lower performance of the experimental group, although this issue requires further investigation. Exercise performed with added respiratory dead space volume from 0.2 to 2 liters and exercise performed with some form of breathing restriction, such as swimming or diving, is known to cause hypercapnia, or an increase in the partial pressure of carbon dioxide in arterial blood [5, 21 24]. This drop in the chemical balance of the system irritates chemoresponsive areas within the cardiovascular system. As a result, pulmonary ventilation increases through an increase in tidal volume [23, 24] and an increase in breathing frequency [25]. It was proven that ventilation increases as P ET CO 2 rises and that ventilation is constant below a given P ET CO 2 level creating a ventilatory threshold in relation to 251

62 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern P ET CO 2 [26]. The present study observed an increase in P ET CO 2 and VCO 2 during exercise that was accompanied with an increase in pulmonary ventilation. This may have been caused by changes in chemoresponsive sensitivity. In the literature on the subject, it was shown that prolonged or frequent environmental exposure to re-inspiring expired air affects the hypoxic ventilatory response, or the increased respiratory response to changes in oxygen tension in exhaled air. This is characterized by a greater increase in pulmonary ventilation during the initial phase of hypoxia [27 29]. In the present study, it is possible that the experimental groups sensitivity to CO 2 and hydrogen ions changed due to training with increased respiratory dead space volume. Such conditions could provoke an increase in the partial pressure of carbon dioxide and a decrease in blood ph levels even at exercise performed at the same intensity (in terms of power) [30]. These are factors that, similar to changes in the partial pressure of oxygen, may irritate the cardiovascular system s chemoreceptors. Conclusions Training with added respiratory dead space volume caused a drop in exercise efficiency, thereby reducing the benefits of an increase in maximal oxygen uptake and reducing the ability to perform submaximal exercise. When performing maximal exercise (such as during a progressive test) that includes high intensity anaerobic efforts, training with added respiratory dead space volume increases exercise capacity by increasing maximal oxygen uptake. References 1. Brown S.J., Cardio-respiratory system efficiency in trained endurance cyclists. Med Sportiva, 2010, 14 (4), Jones N.L., An obsession with CO2. 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Sport Wyczynowy, 2008, 4 6, Yano T., Horiuchi M., Yunoki T., Ogata H., Kinetics of CO 2 excessive expiration in constant-load exercise. J Sports Med Phys Fitness, 2002, 42 (2), Laursen P.B., Blanchard M.A., Jenkins D.G., Acute highintensity interval training improves T vent and peak power output in highly trained males. Can J Appl Physiol, 2002, 27 (4), , doi: /h Anderson D.E., McNeely J.D., Windham B.G., Deviceguided slow-breathing effects on end-tidal CO 2 and heartrate variability. Psychol Health Med, 2009, 14 (6), , doi: / Carey D., Pliego G., Raymond R., How endurance athletes breathe during incremental exercise to fatigue: interaction of tidal volume and frequency. J Exerc Physiol, 2008, 11 (4), Zhao L., Lu J.B., Yang S.Q., Zhu L.H., Effect of dead space loading on ventilation, respiratory muscle and exercise performance in chronic obstructive pulmonary disease. 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63 P. Hebisz, R. Hebisz, M. Zatoń, Dead space loading and breathing pattern 24. Sidney D.A., Poon C.S., Ventilatory responses to dead space and CO 2 breathing under inspiratory resistive load. J Appl Physiol, 1995, 78 (2), Mercier J., Ramonatxo M., Prefaut C., Breathing pattern and ventilatory response to CO 2 during exercise. Int J Sports Med, 1992, 13 (1), 1 5, doi: /s Yano T., Matsura R., Arimistu T., Yamanaka R., Lian C.S., Yunoki T. et al., Ventilation and blood lactate levels after recovery from single and multiple sprint exercise. Biol Sport, 2011, 28 (4), Ursino M., Magosso E., Avanzolini G., An integrated model of the human ventilator control system: the response to hypercapnia. Clin Physiol, 2001, 21 (4), , doi: /j x. 28. Duffin J., Mahamed S., Adaptation in the respiratory control system. Can J Physiol Pharmacol, 2003, 81 (8), Sheel A.W., MacNutt M.J., Control of ventilation in humans following intermittent hypoxia. Appl Physiol Nutr Metab, 2008, 33 (3), , doi: /H Zatoń M., Smołka Ł., Circulatory and respiratory response to exercise with added respiratory dead space. Hum Mov, 2011, 12 (1), 88 94, doi: /v Paper received by the Editors: July 12, 2013 Paper accepted for publication: August 23, 2013 Correspondence address Paulina Hebisz ul. Wrocławska 3b Mirków, Poland paulinahebisz@interia.pl 253

64 2013, vol. 14 (3), The climbing preferences of advanced rock climbers doi: /humo Artur Magiera*, Robert Roczniok The Jerzy Kukuczka Academy of Physical Education, Katowice, Poland Abstract Purpose. Previous studies have broadened the knowledge about the general characteristics of rock climbing. However, there is a lack of research on rock climbers who are at a similar performance level but have different climbing preferences. The purpose of this study was to focus on what similarities and differences are present in the anthropometric, physiological, and training characteristics of advanced rock climbers. Methods. A group of 31 advanced Polish rock climbers volunteered to participate in the study. A questionnaire was administered to determine their climbing preferences. The participants anthropometric characteristics, physical fitness, and aerobic power were measured using standard methods. Results. Similarities were found among the climbers in terms of the training exercises they used, their preference for certain types of rock faces and rock handholds, and their participation in different types of climbing and other sports disciplines. Differences were found among various anthropometrical characteristics, physical fitness, and training exercise frequency between climbers who preferred different climbing styles (on-sight vs. redpoint) or climbing routes ( crux vs. endurance ). Conclusions. During the off-season, various training exercises were used, with the majority employing specialized forms of training (bouldering, repeating previously climbed routes, and leading routes in different styles). They practised on average 10 hours a week and preferred climbing overhanging walls with edge handholds. The best results the climbers achieved in on-sight climbing were in foreign countries and by individuals with high aerobic power measured by an arm ergometer test. Climbers who achieved better results in redpointing used the Campus board more frequently when training and completed their most difficult climbs in Poland. Additional differences were noted between climbers who preferred endurance routes and those who preferred shorter climbing efforts (crux routes), with the former presenting better finger flexor muscle endurance and greater muscle mass. Key words: rock climbing, preferences, training Introduction Rock climbing is a very diverse form of physical activity. It can be differentiated by numerous criteria such as the length and endurance of a climb (from completing one short, intensive bouldering problem to a multi-day, oxygen-deficient Himalayan climb), the type of risk involved (from free soloing on mountain peaks to secured climbs on artificial rock walls), or the amount of tools and equipment required (from only a pair of shoes and a chalk bag to several dozen kilograms of equipment on a multi-day aid climb). The extensive variety of climbing subtypes makes the sport attractive to a wide range of individuals. Even narrowing the above considerations and naming them as one sub-discipline of mountaineering rock climbing still leaves climbers with numerous choices (e.g., climbing style, length, type of rock face) that can be matched to their own personal preferences, talents, and strengths (in terms of skill, ability, body build, psychological readiness, etc.). Among the various climbing preferences individuals may have, there also exist those that relate to the type of actions they prefer to perform over others when training or during the climbing season. Individual preferences are * Corresponding author. subject to contextual personality- and environmentallybased factors that create a system of assessments and priorities to which one thing or activity is valued over another, creating, in effect, a hierarchical scale [1]. They are fundamental in nature and specify the original basis for a person interested in a specific activity. As a result, there exist large inter-individual variations among athletes in the sporting environment. This principle is reflected in sports training by the need to include all the features and characteristics an athlete possesses, while taking into consideration their individual strengths and ability to improve during the training process [2]. The amount of research conducted on rock climbing has been steadily increasing over recent years. The majority of studies have focused on the energy requirements [3 8], anthropometric characteristics, or fitness levels of climbers [9 11]. Some have sought to understand the determinants of sporting success in rock climbing competitions [12, 13]. These studies have increased knowledge on rock climbing per se in terms of its physical demands and the characteristics of its participants. However, there is still a lack of information on the types of climbers that exist, such as differences in climbers at a similar skill level in respect to their preference for one aspect of climbing over another. This study aimed to bridge this gap by focusing on the similarities and differences in advanced climbers in terms of their morpho- 254

65 A. Magiera, R. Roczniok, The climbing preferences of advanced rock climbers functional traits and training characteristics. The study sought to answer the following questions: 1. What are the characteristics of advanced rock climbers in terms of: a) the training exercises they perform during the off-season, b) the rock faces and rock holds they prefer to climb, and c) their involvement in other types of climbing or sports disciplines? 2. Are there any anthropometric and physical fitness characteristics that determine a climber s preference for a particular climbing style (OS 1 or RP 2 )? Additionally, are there any differences in the training exercises used by climbers who prefer OS or RP? 3. Which anthropometric and fitness characteristics as well as training exercises differentiate climbers who prefer short (< 15 m) climbing routes or with only one difficult move to those who prefer endurance-based climbs? Material and methods Thirty-one advanced rock climbers from Poland were recruited to participate in the study. The minimum size of the sample 3 was determined by statistical means. Inclusion criteria when selecting the sample population among advanced Polish climbers were being at least 18 years of age and having on-sighted a route graded at least VI.2, based on the Polish (Kurtyka) scale. Their highest mean graded on-sight climb was VI.4/4+ (VI.2 VI.5+) and VI.5+ (VI.4 VI.7) when redpointing. All were male, with a mean age of ± 5.43 years and 8.32 ± 3.43 years experience in rock climbing. All provided their written informed consent to participate in the study. The study was conducted in Data on the participants were collected by use of a diagnostic survey to determine their climbing preferences and direct observation to measure their anthropometric characteristics and fitness levels. The questionnaire asked the participants about: what kinds of the training exercises (TE) they used when training during the off-season, separated as either general training exercises (G), targeted training exercises (T), or specialized training exercises (S): 1 OS (on-sight) a lead climbing style performed without falling and without aid or foreknowledge of the route. 2 RP (redpoint, based on the German Rotpunkt ) a freeclimbing style performed without falling in one go without rest, although with prior knowledge of the route after having practiced it beforehand. 3 The number of advanced rock climbers in Poland who participated in the 2004 Polish Cup was 48 ( with the estimated number of climbers who had completed an on-sight VI.2 graded climb or higher in Poland to be about 400 (source: own data). general training consisted of: standard warmup exercises (TE G1), resistance training using machines or free weights (TE G2), stretching exercises (TE G3), relaxation exercises (TE G4), coordination exercises (TE G5), running (TE G6), swimming (TE G7), and playing any other team or individual sport (TE G8); targeted training: pull-up bar exercises including pull-ups, chin-ups, lock-offs (TE T1), Bachar ladder (a rope ladder) exercises (TE T2), dynamic climbing exercises performed without the use of the legs on a Campus board, a board with slates of wood attached in a ladder-like configuration (TE T3), finger board training by hanging and climbing on various poles (TE T4), exercises performed on a system wall, a small climbing wall used to repeat climbing movements (TE T5), mixed static-dynamic arm exercises performed on a peg board using only the arms (TE T6), exercises performed using a gymnastic wall bar (TE T7), and other types of exercises similar to the ones above (TE T8); specialized training: bouldering problems consisting of a few although very intensive climbing movements (SE S1), circuit bouldering exercises performed at low height without the use of a safety rope (SE S2), exercises targeted to practice leading in the on-sight, flash, or redpoint styles of climbing while using a safety rope (SE S3), technique exercises (SE S4), tactics training such as how to plan new routes, how to find resting spots, where to attach the rope to the quickdraw, or how to direct a partner where the best handholds are when bouldering (SE S5), repeating well-known routes for practice (SE S6), and any other specialized forms of training (SE S7); the frequency of using the above exercises, the amount of time they spent training per week (Training), the average time spent rock climbing outdoors during the season (Outdoors), and the number of years of climbing experience (Exp.); their preferred types of rock faces (Faces) and rock handholds (Handholds); their preferred type of climbing route: routes with only one difficult move or a short (< 15 m) route performed at a constant, submaximal intensity ( Crux routes), long (> 15 m) routes performed at an intermittent or constant but high intensity ( Endurance routes); their highest graded on-sight (OSmax) and redpoint (RPmax) climb rated on a decimal scale [14], as the currently used grading scales are difficult to subject to statistical analysis; and how many types of climbing they participate in (Climb. types). 255

66 A. Magiera, R. Roczniok, The climbing preferences of advanced rock climbers The reason for the methodological division of the participants training exercises as general, targeted, and specialized was the specificity of each training exercise in regards to their in-season performance (i.e., attempting the climb their most difficult route OSmax and RPmax). Hence, the reason why exercises aimed at improving overall fitness and not only those specifically connected with rock climbing were included in the general training group. Targeted training was considered to be exercises performed on devices that can improve climbing skills by engaging those muscles most involved in climbing. This category included exercises that improve overall physical fitness but have little impact on climbing technique or tactics or the climber s psyche. The last category (specialized training) included all training exercises that required practicing different kinds of climbing handholds involving a high degree of climbing technique and tactics. The climber s anthropometric characteristics were measured using methods widely adopted in sports anthropology. Body composition was assessed by bioelectrical impedance using a BIA-101/SC analyzer (Akern, Italy) and the packaged Bodygram software. The participants were measured for body mass (Mass), body height (Height), Ape Index (the ratio of arm length to body height [13]), percent body fat (BF%), percent muscle mass (MM%), and Body Mass Index (BMI). In addition, the flexibility of the climbers was also assessed by measuring the range of movement of the lower limbs at the hips by use of a goniometer [16]: this included measures of flexion (Flex.) and abduction (Abduc.) as well as hip flexibility in the frog (Frog) position (measured as the distance from the pubic symphysis to the wall when sitting feet placed together with the legs spread as far as possible to the sides). The participants fitness included measures of: finger strength (FSmax the isometric strength of four outstretched fingers on a dynamometer [17]), shoulder muscle strength (SMSmax performing one weighted pull-up with maximum load, 1RM), endurance of Type I flexor finger muscles (FFMmax50% maintaining grip with four fingers at 50% FSmax during a continuous isometric contraction), endurance of Type II flexor finger muscles (FFMmax70% maintaining grip with four fingers at 70% FSmax until exhaustion during an isometric contraction performed for 10 s under load followed by 10 s of rest [18]), and shoulder static muscular endurance (SSME time of bent-hang hang until exhaustion). Aerobic capacity was measured in laboratory conditions on an E-824 ergometer (Monark, Sweden) that was modified for arm crank ergometry. The test began with a load of 15 W, with resistance gradually increased adding 15 W every 2 min and performed until exhaustion. Ergospirometry variables measured during the test included maximal oxygen consumption (VO 2 max) and oxygen uptake at the anaerobic threshold (VO 2 AT). Statistical analysis consisted of calculating basic descriptive statistics (arithmetic mean, standard deviation, median, maximum and minimum values, and variability). The Mann-Whitney U test was used to determine the level of significance. The results were also analyzed with the 2 test and multivariate cluster analysis. Cluster analysis is a useful method for grouping a large number of variables in several subsets (clusters) that relate to one another by use of a dendrogram. The collected data were first standardized by specifying for each value a coefficient calculated from the mean value and standard deviation. The dendrogram was then created based on Ward s method of hierarchical clustering, which minimizes the sum of the squared deviations of any two clusters that can be formed at any stage. As the original values were continuous variables, the Euclidean distance was adopted to measure the similarities of the clusters by the formula: (x, y) ={ i (x i y i ) 2 } ½. Results Table 1 presents the anthropometric characteristics and fitness levels (flexibility, muscular strength, and aerobic capacity during the arm ergometer test) of the rock climbers including their climbing experience and training history. Figure 1. Advanced rock climbers preferences for certain rock faces Figure 2. Advanced rock climbers preferences for certain rock handholds Figure 3. Advanced rock climbers preferences for climbing subtypes 256