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. 15, number 3 (September), 2014

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. 15, number 3 (September), 2014, 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 Józef Rusiecki Olsztyn University College, Olsztyn, 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 Indexed in: SPORTDiscus, Index Copernicus, Altis, Sponet, Scopus, CAB Abstracts, Global Health 7 pkt wg rankingu Ministerstwa Nauki i Szkolnictwa Wyższego Copyright 2014 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: 100

3 2014, vol. 15 (3) contents physical activity, fitness and health Ziemowit Bańkosz, Paweł Szumielewicz Proprioceptive ability of fencing and table tennis practioners Jadwiga Pietraszewska, Anna Burdukiewicz, Aleksandra Stachoń, Justyna Andrzejewska, Tadeusz Stefaniak, Kazimierz Witkowski Body build and the level of development of muscle strength among male jiu-jitsu competitors and strength-trained adults applied sport sciences Chad E. Smith, Brian Lyons, James C. Hannon A pilot study involving the effect of two different complex training protocols on lower body power James Fisher, Christopher Langford The effects of load and effort-matched concentric and eccentric knee extension training in recreational females biomechanics and motor control Alekhya Tirumala, Basavaraj Motimath Effect of resistance tube exercises on kicking accuracy, vertical jump and 40-yard technical test in competitive football players an experimental study physiological aspects of sports Benedikt A. Gasser, Adrian M. Stäuber, Glenn Lurmann, Fabio A. Breil, Hans H. Hoppeler, Michael Vogt Oxygen consumption while standing with unstable shoe design Pantelis Theodoros Nikolaidis, Johnny Padulo, Hamdi Chtourou, Gema Torres-Luque, José Afonso, Jan Heller Estimating maximal heart rate with the 220-age formula in adolescent female volleyball players: a preliminary study Barbara Głuchowska, Aleksandra Żebrowska, Tomasz Kamiński An assessment of exercise tolerance in normobaric hypoxia of patients with diabetes mellitus Type psychological diagnostics of sport and exercise Rainer Schliermann, Isabel Stolz, Volker Anneken The sports background, personality, attitudes, and social competencies of coaches and assistant coaches in the Just Soccer program for pupils with intellectual disabilities Publishing guidelines Regulamin publikowania prac

4 2014, vol. 15 (3), PROPRIOCEPTIVE ABILITY OF FENCING AND TABLE TENNIS PRACTIONERS doi: /humo Ziemowit Bańkosz 1 *, Paweł Szumielewicz 2 1 University School of Physical Education, Wrocław, Poland 2 Fencing Club Wrocławianie, Wrocław, Poland Abstract Purpose. The aim of the study was to compare the spatial component of proprioceptive ability by reproducing a upper limb movement typical in table tennis and fencing. Methods. The research comprised 41 young males of which 12 were table tennis players, 14 fencers, and 15 not involved in any competitive sports as a control. The experiment was based on assessing the precision of pronation and supination of the forearm at the elbow joint in recreating a set movement range by use of a goniometer. Results and conclusions. The results point to a higher level of proprioceptive ability in fencers and table tennis players than the control group but only in respect to the tasks executed with the dominant limb. This is inferred to be the result from the specific character of both sports (i.e. the intensive use of one limb and the consequent laterality of that limb) causing higher sensitivity and proprioception. This may provide a link between swordplay, table tennis, and the level of proprioception. The research methodology used herein may be useful in monitoring fencing training. Although not unequivocally statistically significant, the results indicate the potential for further research in this area. Key words: proprioception, fencing, table tennis, joint position sense Introduction Achieving success in modern sports requires ever-increasing levels of peak physical and mental conditioning, hence the search for newer and more efficient training methods by sports practitioners and researchers [1]. Some researchers have suggested that one way to mobilize fitness potential without increasing strain is through the use of training methods that focus on developing motor coordination abilities such as the ability to kinesthetically differentiate movement and its ranges by way of proprioception [1]. The literature features research that stresses the significance of proprioception in sports yet also notes the complexity and variety of measuring standards due to various factors including difficulties in selecting the methods of assessing the motor skill in question [1, 2]. Nonetheless, the noted dependency between sporting excellence and proprioceptive ability has suggested that this factor should be taken into account during the recruiting process [3]. Lephart et al. [4] compared the accuracy of movement at the knee joint in gymnasts and a control group concluding that specific sports training had a positive influence on knee proprioception by creating enhanced neurosensory pathways in athletes. Similar findings showed that ice hockey players and ballet dancers presented significantly better results than a control group in proprioception of the foot and ankle complex and linked this result with their involvement in athletic activity [5]. When examining figure * Corresponding author. skaters, Starosta et al. [3] found a mutual relationship between the level of proprioceptive sensitivity and athletic achievement, concluding that a higher achievement level is associated with greater proprioception in recreating a set range of movement. Other authors have pointed out the importance of developing sensorimotor perception in beginner swimmers as a base for further improvement [6]. The literature demonstrates that proprioceptive ability is better developed in those parts of the body directly involved in a given sport. Li and Huang [7] drew similar conclusions, finding basketball sharpshooters to exhibit a high level of motion sensitivity in finger and elbow flexors and a great degree of accuracy in choice reaction tasks. The results of Starosta [1] and Starosta et al. [3] may also indicate the particular significance of proprioceptive ability. In these bodies of work, it was found that the differentiation of movement in canoeists during the competitive season is much greater than in the preceding training season. In addition, a significant relationship between the level of proprioception, the results of a motor test, and technique was found [3]. Walaszek and Nosal [8] found that children practicing acrobatic rock n roll were characterized by a higher level of proprioception than a control group. Analysis of the relationship between the results of exercise tests and the precision of applying strength (proprioceptive sensitivity) concluded that research on proprioceptive sensitivity may be useful in monitoring training in numerous sports [2]. Proprioception of movement can be expressed in the selection, execution, or sensation of the position of in- 128

5 Z. Bańkosz, P. Szumielewicz, Proprioceptive ability of fencing and table tennis practioners dividual body parts (the spatial component), the muscle strength involved in the movement (the strength component), and the speed of the movement (the temporal component) [9]. According to Starosta [1], developing proprioceptive ability by initiating, refreshing, and acquiring kinesthetic awareness in the three above-mentioned components may increase training effectiveness. Some authors have emphasized the importance of specific exercises improving movement imagery and kinesthetic ability (based on creating kinesthetic experience) in improving and strengthening proprioception [10]. Table tennis and fencing are sports in which success depends on many interconnected factors, with motor coordination abilities indicated as the most important. Borysiuk [11] found that such abilities have a decisive effect in fencing, especially in the spheres of movement precision and motor adaptation. Czajkowski [12] also highlighted the significance of motor coordination in this sport, emphasizing the special role of time perception as a tactical option and the ability to take an opponent by surprise as an integral part of any bout. Similar conclusions on the significance of motor coordination were found in the literature on table tennis [13, 14]. However, little research has assessed the level and significance of proprioceptive ability in both sports, where the role of such features as sensing (sensing time, the table tennis ball, or weapon) are very important [12, 15]. Those few studies in the literature suggest that proprioceptive ability significantly affects technical skills and sporting success in table tennis [9, 13, 16]. These include skills such as selecting the paddle s position and angle, the selection and strength intensity of a stroke, and discerning the ball s rotation [9, 14]. In fencing, notions such as the sense of the weapon, distance, and pace have been analyzed [17]. Other aspects of particular significance include sensing the steel, sensing the position of the upper limb (forearm, arm, hand) when thrusting or controlling the weapon, directing thrusts towards the target area, movement precision when parrying, the speed at which the arm is straightened, and sensing the steel are of great significance [17]. Due to the fact that the skills related to effective proprioceptive ability seem important both in table tennis and fencing, it would be interesting to determine whether athletes involved in these sports display a high level of motor skills (measured by known and available methods). An answer in the affirmative would emphasize the significance of kinesthetic diversity in both sports and may prompt its inclusion and development in the training process. An assessment of the level of proprioceptive ability could also serve in monitoring training in fencing and table tennis. Therefore, the aim of the study was to compare proprioceptive ability by recreating the position of upper limb movements typical in table tennis and fencing. This would include a search for all correlative relationships between the above factors. It was hypothesized that a higher level of this ability in table tennis and fencing athletes than in untrained individuals may signify the importance of this factor in both sports, determine a link between athletic activity and the level of proprioceptive ability, and also signify the influence of specific training on how proprioceptive ability is shaped. Material and methods Research comprised young males at a similar age level. The sample included 12 table tennis players, 14 fencers, and 15 of their peers as a control. Measures of age, body height, and body mass of the examined groups are presented in Table 1. Table 1. Basic descriptive characteristics of the examined groups for age, body height, and body mass Age (years) Body height (cm) Body mass (kg) SD SD SD Table tennis (n = 12) Fencing (n = 14) Control (n = 15) The fencers were members of a fencing club with about 3 years competitive experience. Competitive experience in the case of the table tennis players was slightly longer at about 5 years. The control group comprised 15 boys from a local primary school not involved in any competitive sport. Testing was performed with a goniometer to assess the precision of recreating a set movement range [3, 9]. The testing apparatus consisted of a specially constructed goniometric appliance to measure forearm pronation and supination at the elbow joint (Figure 1). It consisted of a stationary main body with a rotating cylinder attached to a handle in which the cylinder/handle rotated on a Teflon bearing. A revolving linear potentiometer fixed at the end of the cylinder recorded the angle of rotation. An analog-to-digital converter and Labview software ver (National Instruments, USA) were used to digitally record the angular values when rotating the cylinder/handle. Figure 1. Goniometer and subject positioning 129

6 Z. Bańkosz, P. Szumielewicz, Proprioceptive ability of fencing and table tennis practioners Participants sat on a chair of adjustable height and held the handle of the appliance in such a way that the forearm and the upper arm formed a right angle. The elbow of the arm executing the movement was positioned touching the body (Figure 1). During the examination the forearm s axis coincided with the axis of movement, while the capitulum of the third metacarpal bone coincided with the rotation axis in accordance with the requirements of the measured movement range. The participants were not allowed to familiarize themselves with the appliance prior to testing. For the purpose of the test, participants were blindfolded and asked to execute a pronation movement with the dominant limb three times beginning from the start position of 0 and rotating the handle to an angle of 45. Upon reaching the 45 angle a loud ring was automatically sounded. Immediately after completing the third try, the participants were asked to repeat the same movement five times but this time from memory (blindfolded with no audio cue) and to stop at the 45 angle. The above procedure was then repeated with a supination movement, and then repeated in full for the nondominant hand. The software recorded the maximum range of movement in each direction (pronation/supination) as the angle was reproduced by the subject. The subject s starting position was confirmed before each attempt and adjusted by the researcher conducting the test. The time for repeating the five movements from memory could not exceed 30 s. The extent of proprioceptive differentiation was determined for both the dominant and non-dominant limbs in the pronation and supination movements by calculating the precision rate, or the standard deviation of the recreated angular values, by the formula: 5 i = 1 PR = 2 x i 5, in which PR precision rate, x i the value of the recreated angle of pronation or supination in i th sample, arithmetic mean of the recreated angles. Precision rates were calculated for P-D (pronation of dominant limb), S-D (supination of dominant limb), P-ND (pronation of non-dominant limb), and S-ND (supination of non-dominant limb). A smaller precision rate was treated as an indicator of better proprioceptive ability (in more accurately recreating the spatial component of the movement in question). Statistical analysis of the acquired results was performed with Statistica software (Statsoft, USA). After basic descriptive statistics were calculated, between-group comparisons were made with the Kruskal Wallis one-way analysis of variance and multiple comparisons of mean ranks for all groups. Results The purpose of the experiment was to assess the precision of recreating a pronation and supination movement of the forearm at the elbow joint by three groups: table tennis players, fencers, and a control group not involved in any competitive sports. The table tennis players acquired the lowest precision rates in recreating supination with the dominant limb and pronation with the dominant limb. These values were slightly higher in the case of the non-dominant limb (Table 2). It is interesting to note the high or average mean dispersion and variation of the results as evidenced by the standard deviations and interquartile ranges as well as the relatively average and high values of the coefficient of variation. Table 2. Basic descriptive statistics of the precision rates in recreating pronation with the dominant limb (P-D), supination with the dominant limb (S-D), pronation with the non-dominant limb (P-ND), and supination with the non-dominant limb (S-ND) movements Variable ( ) Me ( ) Min ( ) Max ( ) IQR ( ) SD ( ) CV (%) Table tennis (n = 12) Fencing (n = 14) P-D S-D t P-ND S-ND P-D t S-D * P-ND S-ND Control (n = 15) P-D S-D P-ND S-ND mean, Me median, Min minimum, Max maximum, IQR interquartile range, SD standard deviation, CV coefficient of variation, * difference from control at p < 0.05, t difference from control group at p <

7 Z. Bańkosz, P. Szumielewicz, Proprioceptive ability of fencing and table tennis practioners A similar distribution of the results and their values may be observed in the group of fencers. The arithmetic means and medians were slightly lower in the tests performed with the dominant limb than the non-dominant one (Table 2). Of interest is that the difference in performing the pronation movement was quite considerable. Analysis of the dispersion and variation of the results indicates smaller differentiation than in the table tennis group. Analysis of the results in the control group revealed larger median and mean values in most of the analyzed movements compared with both groups of athletes (Table 2). Coefficients of variation and standard deviations in all four analyzed movements were similar and at an average level, signifying average intragroup differences. Analysis also included comparing the precision rates obtained in the tested movements by all of the groups. As normal distributions were not found in some of the movements, intergroup differences were assessed using non-parametric tests. Comparison of the arithmetic means and medians found similar results between the table tennis players and fencers in virtually all four of the tested movements, with no statistical differences revealed by Kruskal Wallis one-way analysis of variance. Precision rates obtained by the athletes were lower than the control group in movements performed with the dominant limb in both pronation and supination (a sign of better ability). Kruskal Wallis one-way analysis of variance found a statistically significant difference (H = 6.20, p = ) only in supination of the dominant limb (S-D). The post hoc multiple comparisons of mean ranks for all groups did not confirm a statistically significant difference, with p values of 1.00 between fencers and table tennis players, 0.15 between fencers and controls, and 0.07 between table tennis players and controls. No statistically significant differences between the athletes and the control group were observed in the tests performed with the non-dominant limb. Discussion This study analyzed the spatial component of proprioceptive ability, which involves sensing and differentiating the position of individual body parts, in this case, the position of the forearm at the elbow joint during a pronation and supination movement. The literature claims that the level of proprioceptive, or kinesthetic, sensitivity is the highest in parts of the body involved in a given sport. This was found to be the case in basketball players, who displayed greater sensitivity and a higher level of upper limb proprioception [7]. Arman et al. found that professional ballet dancers demonstrated greater accuracy than a control group in positioning upper and lower limb joints and hypothesized this to be the effect of improved proprioceptive response as a result of dance practice [18]. Other researchers have also pointed out the significance of proprioceptive sensitivity in soccer as well as the connection between the level of proprioception and improved technique in karate [19, 20]. Rejman et al. [21] examined monofin swimmers and suggested that the high level of kinesthetic response in this group was the result of an adaptation prompted by the specificity of the additional sensory stimulus received in the form of feedback from the large surface area of the monofin. Similar conclusions can be inferred by the results of the present study, although better movement execution by the two athlete groups was only observed in the dominant limb when compared with the control group. The table tennis players and fencers displayed lower mean and median precision rates than the control group for the dominant limb in the supination movement, albeit these differences were not unequivocally statistically significant as determined by post-hoc testing. This may suggest a relationship between the practice of swordplay and table tennis and the level of proprioceptive ability. The differences in executing these movements with the dominant limb may result from the specific character of both sports (hitting a ball with a paddle, holding and wielding a blade) being performed with the dominant limb. It is possible that practicing a sport that involves numerous repetitions of precise arm, forearm, hand, or finger movements may increase the proprioceptive sensitivity of the more frequently used limb, and may solidify or refresh kinesthetic sensation [1]. This may account for the better results (especially in the case of the fencers) in the supination movement. In the case of the non-dominant limb, the two athlete groups did not differ from the control group. In table tennis, supination and pronation movements are performed to change the angle of the paddle [13]. In fencing, supination and pronation movements at the elbow joint are characteristic during parrying, especially in the Quarte (parry 4) and Sixte (parry 6) [17]. The results of the present study may corroborate the extensive use of these types of parries in training and competition by the examined fencers, while at the same time, give rise the use of the research methodology herein to monitor training progression. Studies on proprioception have indicated that athletes are characterized by greater proprioceptive differentiation than individuals not involved any sports [4, 8, 18]. This difference between a trained and untrained population was explained by the specificity of the practiced sport. However, these differences may in fact result from the development of proprioceptive ability during the training process typical of a given sport. In addition, a higher level of this ability may also result from the general recruitment and selection criteria of a given sport, as evidenced by the relationship found between proprioceptive ability and skill level [1, 3, 22]. In regards to the previously cited works, there are also reports that have indicated a lack of a clear difference 131

8 Z. Bańkosz, P. Szumielewicz, Proprioceptive ability of fencing and table tennis practioners in reproducing movements between athletes and untrained individuals. Jerosh et al. [23] compared female table tennis players with a control group finding no differences in the accuracy of reproducing movements at the elbow joint. The differences in the results of studies on proprioceptive ability may attest to its large variability and dependence on numerous factors as well as the use of different measurement methods assessing its level. Some researchers have suggested that the components (strength, spatial, and temporal) of proprioceptive ability are relatively independent of each other, that no inherent relationship exists with the age of an athlete, and that data collected on this ability is highly variable. Instead, it is believed that the level of each individual component depends on physical and mental health as well as the level of motivation [24, 25]. Conclusions 1. The results point to a higher level of proprioceptive differentiation in fencers and table tennis players than in the control group although only for movements executed by the dominant limb. This may be the result of the specific character of both sports, i.e. the intensive use of one limb, and may therefore provide a link between swordplay, table tennis and proprioceptive ability. Although not unequivocally statistically significant, the results indicate the potential for further research in this area. 2. The fencers and the table tennis players executed the task of forearm supination (by the dominant limb) better than the control group and is believed to originate from the use of this movement in both sports. It can be considered that the research methodology used herein may serve in monitoring training progress in these sports. References 1. Starosta W., The concept of modern training in sport. Studies in Physical Culture & Tourism, 2006, 13 (2), Zatoń M., Błacha R., Jastrzębska A., Słonina K., Repeatability of pressure force during elbow flexion and extension before and after exercise. Hum Mov, 2009, 10 (2), , doi: /v Starosta W., Aniol-Strzyzewska K., Fostiak D., Jablo nowska E., Krzesinski S., Pawlowa-Starosta T., Precision of kinesthetic sensation element of diagnosis of performance of advanced competitors. Biol Sport, 1989, 6 (3), Lephart S.M., Giraldo J.L., Borsa P.A., Fu F.H., Knee joint proprioception: a comparison between female intercollegiate gymnasts and controls. Knee Surg Sports Traumatol Arthrosc, 1996, 4 (2), , doi: / BF Li J.X., Xu D.Q., Hoshizaki B., Proprioception of foot and ankle complex in young regular practitioners of ice hockey, ballet dancing and running. Res Sports Med, 2009, 17 (4), , doi: / Ebahrawi M., The effect of kinesthetic perception exercises on distance and time start in crawl swimming. Ovidius University Annals, Series Physical Education & Sport/ Science, Movement & Health, 2014, 14 (1), Ji L., Huang B., A discussion on psychological characteristics of female basketball sharpshooters (Abstract). Sport Science/ Tiyu Kexue, 1987, 7 (2), Walaszek R., Nosal T., Assessment of the impact of oneyear training in acrobatic rock n roll on overall motor coordination in eight-year-old children. Baltic Journal of Health and Physical Activity, 2014, 6 (2), 90 99, doi: /bjha Bańkosz Z., Skarul A., Changes in the level of kinesthetic differentiation ability in table tennis players. Studies in Physical Culture & Tourism, 2010, 17 (1), Toussaint L., Blandin Y., Behavioral evidence for motor imagery ability on position sense improvement following motor imagery practice. Movement & Sport Sciences Science & Motricit e, 2013, 82, 63 68, doi: / sm/ Borysiuk Z., Complex evaluation of fencers predisposition in three stages of sport development. Biol Sport, 2006, 23 (1), Czajkowski Z., The essence and importance of sense of timing in fencing. Studies in Physical Culture & Tourism, 2009, 16 (3), Bańkosz Z., Accuracy of movement repeatability and sport level of table tennis players. In: Sadowski J., Niźnikowski T. (eds.), Coordination motor abilities in scientific research, AWF Warszawa, Biała Podlaska, 2008, Hotz A., Muster M., Table tennis: teaching and learning [in German]. Meyer & Meyer, Aachen Starosta W., Felbur B., Structure and conditioning of ball feeling in the opinions of table tennis players and coaches. In: Sadowski J., Starosta W. (eds.), Movement Coordination in team sport games and martial arts. AWF, Warszawa 1998, Bańkosz Z., Błach W., Kinesthetic differentiation ability and playing precision in table tennis players [in Polish, abstract in English]. Medycyna Sportowa, 2007, 23 (2), Czajkowski Z., Understanding fencing. The unity of theory and practice. SKA SwordPlay Books, New York Arman E., Gulbin R.N., Rana S.V., Joint position sense in Turkish professional ballet dancers. Journal of Physical Education and Sport Sciences, 2013, 7 (1), Cynarski W.J., Obodyński K., Litwiniuk A., The technical advancement and level of chosen coordination abilities of people practicing karate. In: Sadowski J. (ed.), Coordination motor abilities in scientific research. AWF, Warszawa, Biała Podlaska 2005, Buraczewski T., Cicirko L., Storto M., Correlation between the level of development of coordination motor abilities and a special skill in children at the beginner s stage of football training. In: Sadowski J., Niźnikowski T. (eds.), Coordination motor abilities in scientific research. AWF, Warszawa, Biała Podlaska 2008, Rejman M., Klarowicz A., Zatoń K., An evaluation of kinesthetic differentiation ability in monofin swimmers. Hum Mov, 2012, 13 (1), 8 15, doi: /v Bańkosz Z., The kinesthetic differentiation ability of table tennis players. 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9 Z. Bańkosz, P. Szumielewicz, Proprioceptive ability of fencing and table tennis practioners 23. Jerosch J., Thorwesten L., Reuter M., Proprioceptive capabilities of the elbow joint in elite female table tennis players [in German]. Deutsche Zeitschrift für Sportmedizin, 1997, 48 (2), 43 44, Kollarovits Z., Teplicka S., Testing of sensorimotor abilities in table tennis and tennis [in Slovak, abstract in English]. Acta Facultatis Educationis Physicae Universitatis Comenianae, 1995, 37, Kollarovits Z., Teplicka S., Stability of kinesthetic differentiation abilities in the period of several months [in Slovak, abstract in English]. Telesna Vychova & Sport, 1999, 9 (1), Paper received by the Editor: April 3, 2014 Paper accepted for publication: June 23, 2014 Correspondence address Ziemowit Bańkosz Katedra Dydaktyki Sportu Akademia Wychowania Fizycznego al. I.J. Paderewskiego Wrocław, Poland ziemowit.bankosz@awf.wroc.pl 133

10 2014, vol. 15 (3), Body build and the level of development of muscle strength among male jiu-jitsu competitors and strength-trained adults doi: /humo Jadwiga Pietraszewska*, Anna Burdukiewicz, Aleksandra Stachoń, Justyna Andrzejewska, Tadeusz Stefaniak, Kazimierz Witkowski University School of Physical Education, Wrocław, Poland Abstract Purpose. The aim of the present study was to assess the morpho-functional characteristics of male jiu-jitsu practitioners against a sample of strength-trained university students. Methods. The all-male research sample included 49 jiu-jitsu competitors and 30 university students actively involved in strength training. Measures of body mass and height, lower extremity length, sitting height, arm span, trunk width, skeletal breadths, circumferences and skinfold thicknesses of the trunk and extremities were collected. Body tissue composition was assessed using bioelectrical impedance analysis. Somatotype was classified according to the anthropometric method of Heath and Carter. Participants also performed three motor tests composed of the standing long jump, flexed arm hang, and sit-ups and two dynamometer tests measuring handgrip and back muscle strength. Differences between the measured characteristics in both samples were analyzed using Student s t test. Pearson s correlation coefficient was used to the determine the relationships between the morphological characteristics and the results of the motor tests. Results. The jiu-jitsu sample was slightly smaller than the strength-training students. In contrast, body mass was almost identical in both groups. The remaining length, height, and skinfold characteristics also did not differ significantly between the groups. Only hip breadth was significantly larger in the jiu-jitsu sample. No between-group differences were noted in the levels of endomorphy, mesomorphy, and ectomorphy. The composite somatotype of the jiu-jitsu athletes ( ) was very similar to that of the strength-trained students ( ). Statistically significant differences were observed in the tests assessing muscle strength. Handgrip and back muscle strength was greater in the strength-training students, whereas the jiu-jitsu athletes performed better in all three motor tests. Conclusions. The minor morphological differences between the jiu-jitsu and strength-training groups may be due to the different sporting level of the participants. Whereas the intense weight training regime of the strength-training students allowed them to achieve higher results in the dynamometer tests, the more multidimensional aspect of jiu-jitsu training was reflected in achieving better results in the motor tests. Key words: jiu-jitsu, body build, motor tests Introduction The body build profile of athletes is the result of both athlete selection criteria and training loads. Each sport involves various form of training, the aim of which is to generally improve certain fitness measures and overall physical performance, whereas the aim of more targeted training programs specific to each sport is to induce specific changes in body morphology as well as various functional characteristics. It is the combination of optimal training and the most suitable somatic predispositions that allow an athlete to attain the best results in today s ever more specialized and technical world of sports. One of the most basic elements of any sports training program is developing strength [1]. Muscle strength plays a key role in determining sporting success not only in typical strength sports such as weightlifting, powerlifting, and bodybuilding [2], but also in martial arts, track and field, and team sports. * Corresponding author. In recent years there has been an upsurge of interest in jiu-jitsu among the martial arts community with its combination of elements from karate and judo [3]. The mixed style of jiu-jitsu promotes a wide variety of techniques and tactics. The full range of jiu-jitsu techniques covers grips, throws, holds, joint locks, chokes, hits, kicks, and inflicting blows on sensitive parts of the body in various ways. One of the defining concepts behind jiu-jitsu is that a theoretically weaker athlete should be able to successfully subdue a stronger, larger opponent. Hence, jiu-jitsu favors individuals with high levels of flexibility, agility, speed, coordination, and balance [4] and not pure physical strength. Nonetheless, strength training is important for jiu-jitsu practitioners as it aids in certain moves such as throwing or choking. For these moves and others, upper body strength plays a large role as jiu-jitsu is a close and full contact sport that does not provide the space needed for more dynamic moves [5]. Alongside the importance of upper body strength is also muscular endurance, used to hold and maintain the most advantageous position when grappling against an opponent. Alongside the above, handgrip strength is also important as it is very effective in holding down an opponent by their kimono. 134

11 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners Research on the somatotypes of martial arts athletes in different weight classes is quite comprehensive. However, relatively little work has been performed on jiu-jitsu practitioners. Of those few available studies, most have focused on reporting mean body mass and height, body tissue composition, or types of body build. There remains a paucity of information when considering detailed anthropometric data and comparing morphological characteristics with strength measures. Particular interesting seems to be comparing the motor performance (strength-related) of jiu-jitsu practitioners against athletes specialized in strength training. The aim of the present study was to therefore compare the morphology, body tissue composition, and strength capabilities of jiu-jitsu against a population engaged in strength-training. This included examining the relationship between the strength levels and anthropometric characteristics between both groups. Material and methods The all-male research sample included 49 professional jiu-jitsu practitioners (mean age years) and 30 university students actively involved in strength training (mean age years). All participants weighed between kg. The jiu-jitsu group had been involved in the sport between 4 to 12 years and trained on average four times per week for 2 hours. The comparative group had been involved in an adaptive strength training program for 3 months whose aim was to improve muscular endurance [6]. This group trained three times per week (every other day) by lifting weights. Each training session consisted of two exercises targeting each major muscle group, with ninety seconds of rest provided between the exercises. The first training session began by performing one set of 19 repetitions for each exercise at a suitable weight. The number of repetitions was then increased by one each subsequent training session until reaching 24 repetitions. Afterwards the number of sets was increased to two, with the participants again completing 19 repetitions per set with the number of repetitions increased by one each subsequent exercise session until again reaching 24. Finally, participants completed three sets (from 19 to 24 repetitions). The next step was to return to completing two sets of 19 repetitions in each exercise but this time increasing the weight by 5% in each subsequent session. Upon completing this introductory phase, training was varied for each exercise by increasing, in order, the number of repetitions (from 19 to 24), then the number of sets (from two to three), and then the weight (by 5%). Data were collected through anthropometric measurement and administering fitness/strength tests. An anthropometer (GPM, Switzerland) was used to measure body height, lower extremity length, sitting height, and arm span. Measures of the trunk and extremities were performed using a spreading caliper of the same manufacturer. These included chest diameter, chest depth, biacromial diameter, biiliocristal diameter, and deltoid muscle diameter. Measures of bone breadths included elbow breadth and knee breadth. In addition, circumferences of the neck, shoulder, chest, waist, hips, arm (contracted and relaxed), and the maximal circumferences of the forearm, thigh, and calf were taken. A body fat caliper (Harpenden, UK) was used to obtain skinfold thicknesses at the subscapular, triceps, suprailiac, abdominal, and calf sites. Body mass was assessed using an electronic scale. The relationship between height and mass was assessed by body mass index. Somatotype was classified according to Sheldon s method of somatotopy as modified by Heath and Carter to determine the levels of endomorphy, mesomorphy, and ectomorphy. Body tissue composition was determined using a BIA 101 bioelectrical impedance analyzer (Akern, Italy) with the packaged Bodygram software. Variables considered for analysis included body fat mass, lean body mass, and water content. Muscle strength was assessed by dynamometer testing; this included measuring (a) handgrip strength using an adjustable hand dynamometer (Takei, Japan) with a measuring range of kgf (kilogram-force) and 0.5 kgf accuracy and (b) back muscle strength using a back dynamometer of the same manufacturer with a measuring range of kgf and 0.5 kgf accuracy. Physical fitness was assessed by three motor tests consisting of the standing long jump (distance jumped), flexed arm hang (time spent hanging), and sit-ups (number completed within a set time). Basic statistical methods were used to analyze the obtained results. Means and standard deviations were calculated. The statistical distribution of the variables were assessed with the Kolmogorov Smirnov test, finding it did not differ significantly from a normal distribution. On this basis all subsequent statistical methods assumed a normal distribution. Inter-group differences were determined by Student s t test, whereas the relationships between the muscle strength variables and morphological characteristics were examined using Pearson s product-moment correlation coefficient. The study was financed by the Polish Ministry of Science and Higher Education in a project titled Muscle strength development among martial arts and fighting sports athletes differentiated by morphological structure (No. NRSA ). The study design was approved by the Ethics Committee of the University of Physical Education in Wroclaw, Poland and all participants provided their written informed consent. Results Body mass was almost identical in both groups (Table 1). However, the jiu-jitsu sample was slightly smaller than the strength-training students, whereas those strength lifting had significantly smaller biiliocristal 135

12 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners diameter and chest depth values. On the other hand, the jiu-jitsu practitioners were characterized by a smaller hip circumference (Table 2). No significant differences were found between both groups among the skinfold thickness and length/height characteristics. For body composition a significantly higher percentage of lean body mass and water content was presented by the jiujitsu practitioners (Table 3). Conversely, the strengthtraining group had higher fat content, measured both in kilograms and as a percentage. No between-group differences were noted in the levels of endomorphy, mesomorphy, and ectomorphy. The somatotype of the jiu-jitsu athletes ( ) was very similar to that of the strength-trained students ( ). A number of significant differences were observed in the tests assessing muscle strength (Table 4). Although the differences for handgrip strength were not statistically significant, the strength-training group presented slightly higher results. Significantly higher values were found in this group for back muscle strength. In turn, the jiu-jitsu athletes performed better in all three motor tests (standing long jump, flexed arm hang, and sit-ups). However, a statistically significant difference was recorded only in the standing long jump test. In both groups, a significant positive correlation was observed between the majority of the somatic characteristics and the dynamometer tests (handgrip and back strength). In the case of the other three motor tests, any correlations with the morphological characteristics were quite low, with the majority non-significant (Table 5, 6). However, the strength-training group featured a slightly more pronounced relationship between a lower time (poorer result) in the flexed arm hang test and an increase in the values of the analyzed somatic characteristics. A statistically significant negative correlation was found between flexed arm hang time and the circumferences of the thigh and calf, whereas a positive correlation was found between flexed arm hang test and ectomorphy. No statistically significant dependencies were observed between any of the somatic characteris- Variable Table 1. Statistical characteristics of the length/height measurements and body mass Jiu-jitsu group Strength-training group Mean SD Mean SD p Body mass (kg) Body height (cm) Lower extremity length (cm) Sitting height (cm) Arm span (cm) Biacromial diameter (cm) Deltoid muscle diameter (cm) Chest diameter (cm) Chest depth (cm) Biiliocristal diameter (cm) Elbow breadth (cm) Knee breadth (cm) Values in bold denote statistical significance at p < 0.05 Table 2. Statistical characteristics of the circumference measurements Variable Jiu-jitsu group Strength-traininggroup Mean SD Mean SD p Neck circumference (cm) Shoulder circumference (cm) Chest circumference (cm) Waist circumference (cm) Arm circumference relaxed (cm) Arm circumference contracted (cm) Maximal forearm circumference(cm) Hip circumference (cm) Maximal thigh circumference (cm) Maximal calf circumference (cm) Values in bold denote statistical significance at p <

13 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners Table 3. Statistical characteristics of somatotype, skinfold thickness, and body tissue composition Variable Jiu-jitsu group Strength-training group Mean SD Mean SD p Body mass index Endomorphy Mesomorphy Ectomorphy Subscapular skinfold thickness (mm) Triceps skinfold thickness (mm) Suprailiac skinfold thickness (mm) Abdominal skinfold thickness (mm) Calf skinfold thickness (mm) Fat mass (kg) Fat-free mass (kg) Total body water (kg) Fat mass (%) Fat-free mass (%) Total body water (%) Values in bold denote statistical significance at p < 0.05 Table 4. Statistical characteristics of the motor test results Variable Jiu-jitsu group Strength-training group Mean SD Mean SD p Right handgrip strength (kgf) Left handgrip strength (kgf) Back strength (kgf) Flexed arm hang (s) Standing long jump (cm) Sit-ups (n) Values in bold denote statistical significance at p < 0.05 tics and the results of the flexed arm hang test in the jiu-jitsu group. For the standing long jump a positive correlation was established between this motor test and a number of the length/height characteristics in both groups. In the strength-training group, the strongest positive correlation was observed between standing long jump performance and lower extremity length. For the jiu-jitsu group, the largest positive correlations were with body height, knee breadth, and circumference of the waist. A clear result was found between poorer long jump distance and increased skinfold thickness among the students involved with strength training. No such dependency was found in the jiu-jitsu group. The correlation coefficients between the sit-ups test and the morphological characteristics in both groups had low values. Only in the strength-training group could a dependency be observed between an improvement in the number of sit-ups with a stronger and better developed upper body. Discussion The techniques and training methods used in combat sports are vastly diverse. As a result, there are no specific morphological criteria for those involved in these sports. However, research conducted on judo, jiu-jitsu, and karate practitioners showed only a slight variation in their morphological structure [3, 7]. Many authors have indicated that choosing the most optimal fighting technique in a combat sport may be better determined by an athlete s somatic predisposition [8]. In practice, Lech et al. found that taller and thinner individuals were more likely to use leg techniques, while those larger and shorter had a larger preponderance of using hand techniques [9]. In the same study, differences were also found in the effectiveness of countermaneuvers depending on body height. It is nonetheless apparent that the specialized forms of training inherent in combat sports cause practitioners to develop in ways most practical for combat and, as a re- 137

14 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners Table 5. Pearson s correlations between the results of the motor tests and the morphological characteristics and body tissue components in the jiu-jitsu group Variable Right handgrip strength Left handgrip strength Back strength Flexed arm hang Standing long jump Sit-ups Body mass Body height Lower extremity length Sitting height Arm span Biacromial diameter Deltoid muscle diameter Chest diameter Chest depth Biiliocristal diameter Elbow breadth Knee breadth Neck circumference Shoulder circumference Chest circumference Waist circumference Arm circumference relaxed Arm circumference contracted Maximal forearm circumference Hip circumference Maximal thigh circumference Maximal calf circumference Subscapular skinfold thickness Triceps skinfold thickness Suprailiac skinfold thickness Abdominal skinfold thickness Calf skinfold thickness Fat-free mass Total body water Fat mass Endomorphy Mesomorphy Ectomorphy sult, be distinguished from athletes involving in other disciplines. The present study found minor differences among some of the analyzed morphological and functional characteristics between jiu-jitsu practitioners and individuals engaged in strength training. Based on the literature on the subject, the mass height values of the jiu-jitsu group were typical for practitioners of this sport. Andreato et al. studied Brazilian jiu-jitsu practitioners from three ranks finding mean body mass to be 75.4 kg and mean body height cm [10]. Similar values were reported by Costa et al., with body mass 75.2 ± 11.2 kg, body height ± 8.2 cm, and BMI 25.1 ± 3.8 kg/m 2 [4]. These results show this to be the most common mass height relationship in jiu-jitsu practitioners and therefore can be used as benchmark for athletes as the mass and height range needed to better take advantage of the full range of techniques and counter-maneuvers in this sport. Analysis of skinfold thickness indicated a similar distribution of fat in both groups. The largest values were recorded at the subscapular and abdominal sites, although the jiu-jitsu group had significantly lower body fat percentage. However, body fat content was larger in both groups when compared with values reported by other authors [8, 11], with this possibly explained by the fact that the participants examined in this study were less experienced than in the above-cited studies. Due to the nature of combat, low body fat content in different parts of the body is known to help in fighting at a faster speed as well as reacting more quickly to an opponent s moves [11]. 138

15 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners Table 6. Pearson s correlations between the results of the motor tests and the morphological characteristics and body tissue components in the strength-training group Variable Right handgrip strength Left handgrip strength Back strength Flexed arm hang Standing long jump Body mass Body height Lower extremity length Sitting height Arm span Biacromial diameter Deltoid muscle diameter Chest diameter Chest depth Biiliocristal diameter Elbow breadth Knee breadth Neck circumference Shoulder circumference Chest circumference Waist circumference Arm circumference relaxed Arm circumference contracted Maximal forearm circumference Hip circumference Maximal thigh circumference Maximal calf circumference Subscapular skinfold thickness Triceps skinfold thickness Suprailiac skinfold thickness Abdominal skinfold thickness Calf skinfold thickness Fat-free mass Total body water Fat mass Endomorphy Mesomorphy Ectomorphy Sit-ups In terms of somatotype (endomorphy, mesomorphy, and ectomorphy), the body type of the participants in this study was found to be in line with those found in strength-training and combat sports populations [12 15]. The dominance of mesomorphy in both groups point to the strong development of muscle mass and muscle hypertrophy as well as increased skeletal size. The above characteristics could also be observed in the high values recorded in the handgrip strength test. Here, handgrip strength (right and left hand) values were larger than those recorded by Andreato et al. on Brazilian jiu-jitsu practitioners in the same weight class (70 90 kg), who obtained 43.7 ± 4.8 kgf for the right hand and 40.1 ± 3.8 kgf for the left hand [5]. This was especially visible in the high values attained by the strength-training participants in the present study and can be assumed to be the result of their involvement in such an intense weight training program [2, 16]. Of interest is the fact that Diaz et al. did not find larger absolute handgrip strength values for a population of judokas when compared with an untrained sample [17]. However, the judokas in that study were found to be more resistant to fatigue during this test, with this difference in strength endurance associated with the need to maintain a strong grip on an opponent s kimono during combat. The standing long jump is used to assess lower extremity explosive strength. The ascendancy of the jiujitsu group over the strength-training group may stem from their multifaceted training regime that develops not just strength but also flexibility, agility, speed, coordination, and balance. In addition, the muscular work involved in combat has both a static and dynamic charac- 139

16 J. Pietraszewska et al., Morpho-functional characteristics of jiu-jitsu practitioners ter [18]. The distance jumped in the standing long jump by the jiu-jitsu participants (233.5 m) in the present study was quite similar to that presented by Sertic et al. on a population of judokas, achieving a mean distance of cm [18]. The results of the flexed arm hang and sit-ups test in both groups demonstrate the participants high level of muscular endurance. This result confirms that abdominal muscle and upper body strength are critical in martial arts, and that martial arts training is justifiably focused on improving these elements [5]. In the current study, significant positive correlations were observed between body mass and the results of the dynamometer tests (handgrip and back strength). Detanico et al. also described a strong positive relationship between body mass and maximal strength [19] and that, in the case of athletes, body mass was associated with greater musculature. Consecutively, muscle strength was found to be proportional to the crosssectional area of skeletal muscle [1]. This was also been confirmed in the present study by the significant correlation between handgrip strength and circumference of the upper limbs. Conclusions No pronounced differences were observed between the somatotypes of the jiu-jitsu practitioners and the strength-training university students. This may be may be due to the different sporting level of the participants. However, the better dynamometer results achieved by the strength-training group can be linked to their intensive strength training regime. On the other hand, the more multidimensional aspect of jiu-jitsu training was reflected in achieving better results in the motor tests and undoubtedly connected with the high fitness of these individuals. References 1. Zatsiorsky V.M., Kraemer W.J., Science and practice of strength training. Human Kinetics, Champaign Tan B., Manipulating Resistance Training Program Variables to Optimize Maximum Strength in Men: A Review. J Strength Cond Res, 1999, 13 (3), Sterkowicz-Przybycień K., Ambroży T., Sexual dimorphism in anthropometric and fitness measurements of top ju-jitsu contestants. J Combat Sports and Martial Arts, 2013, 2 (2), 4, , doi: / Costa E.C., Santos C.M., Prestes J., Silva J.B., Knackfuss M.I., Acute effect of static stretching on the strength performance of jiu-jitsu athletes in horizontal bench press. Fit Perf J, 2009, 8 (3), , doi: /fpj e. 5. Vidal Andreato L., Franzói de Moraes S.M., Lopes de Moraes Gomes T., Del Conti Esteves J.V., Vidal Andreato T., Franchini E., Estimated aerobic power, muscular strength and flexibility in elite Brazilian Jiu-Jitsu athletes. Science & Sports, 2011, 26, , doi: /j.scispo Stefaniak T., Atlas of universal strength exercises. Part 1 [in Polish]. BK, Wrocław Ibri L., Shala S., Discriminative analysis of morphologic and motoric parameter to judo and karate sportiest boys. Crnogorska Sportska Akademija Sport Mont, 2013, 37, 38, 39, Sterkowicz-Przybycień K., Technical diversification, body composition and somatotype of both heavy and light Polish ju-jitsukas of high level. Science & Sports, 2010, 25, , doi: /j.scispo Lech G., Sterkowicz S., Rukasz W., Significance of body height in martial arts (as exemplified by judo fighters). Hum Mov, 2007, 8 (1), Vidal Andreato L., Franzói de Moraes S.M., Del Conti Esteves J.V, de Araujo Pereira R.R., Lopes de Moraes Gomes T.L., Vidal Andreato T. et al., Physiological responses and rate of perceived exertion in Brazilian jiujitsu athletes. Kinesiology, 2012, 44, 2, Pieter W., Bercades L.T., Kim G.D., Relative Total Body Fat and Skinfold Patterning in Filipino National Combat Sport Athletes. J Sports Sci Med, 2006, 5, Charzewski J., Głaz A., Kuźnicki S., Somatotype characteristics of elite European wrestlers. Biol Sport, 1991, 8 (4), Huygens W., Claessens A.L., Thomis M. et al., Body composition estimations by BIA versus anthropometric equations in body builders and other power athletes. J Sports Med Phys Fitness, 2002, 42 (1), Imran M., Hussain I., Murtaza S.T. et al., A Comparative Study of Body Builders and Weight Lifters on Somatotypes. Journal of Education and Practice, 2011, 2 (3), Sterkowicz-Przybycień K., Sterkowicz S., Żarów R., Somatotype, Body Composition and Proportionality in Polish Top Greco-Roman Wrestlers. J Hum Kinet, 2011, 28, Deschenes M.R., Kraemer W.J., Performance and physiologic adaptations to resistance training. Am J Phys Med Rehabil, 2002, 81 (11), 3 16, doi: /01.PHM E Dias J.A., Wentz M., Külkamp W., Mattos D., Goethel M., Borges Júnior M., Is the handgrip strength performance better in judokas than in non-judokas? Science & Sports, 2012, 27 (3), 9 14, doi: /j.scispo Sertić H., Sterkowicz S., Vuleta D., Influence of latent motor abilities on performance in judo. Kinesiology, 2009, 41 (1), Detanico D., Budal Arins F., Dal Pupo J., dos Santos S.G., Strength parameters in judo athletes: an approach using hand dominance and weight categories. Hum Mov, 2012, 13 (4), , doi: /v x. Paper received by the Editor: June 17, 2014 Paper accepted for publication: July 25, 2014 Correspondence address Jadwiga Pietraszewska Katedra Motoryczności Sportowca Akademia Wychowania Fizycznego al. I.J. Paderewskiego 35, P Wrocław, Poland jadwiga.pietraszewska@awf.wroc.pl 140

17 2014, vol. 15 (3), A pilot study involving the effect of two different complex training protocols on lower body power doi: /humo Chad E. Smith 1 *, Brian Lyons 2, James C. Hannon 3 1 Weber State University, Health Promotion and Human Performance, Utah, UT, USA 2 Arkansas Tech University, Health and Physical Education, Russellville, AR, USA 3 West Virginia University, College of Physical Activity and Sport Sciences, Morgantown, WV, USA Abstract Purpose. Complex training (CT) involves the coupling of two exercises ostensibly to enhance the effect of the second exercise. Typically, the first exercise is a strength exercise and the second exercise is a power exercise involving similar muscles. In most cases, CT is designed to enhance power. The purpose of this study was twofold. First, this study was designed to determine if lower body power could be enhanced using complex training protocols. Second, this study investigated whether the inclusion of a power exercise instead of a strength exercise as the first exercise in CT would produce differences in lower body power. Methods. Thirty-six recreationally-trained men and women aged 20 to 29 years attending a college physical education course were randomly assigned to one of three groups: squat and countermovement squat jumps (SSJ), kettlebell swings and countermovement squat jumps (KSJ), and a control (CON). Training involving CT lasted 6 weeks. All participants were pre- and posttested for vertical jump performance in order to assess lower body power. Results. Vertical jump scores improved for all groups (p < 0.01). The results also indicated that there were no statistically significant differences between group scores across time (p = 0.215). The statistical power for this analysis was low (0.312), most likely due to the small sample size. However, the results did reveal a trend suggesting that the training improvements were greater for both the SSJ and KSJ groups compared with the CON (by 171% and 107%, respectively) although significance was not reached. Conclusions. Due to the observed trend, a replication of this study with a greater number of participants over a longer period of time is warranted. Key words: complex training, lower body power Introduction Athletes are always searching for training techniques to gain a competitive edge. New methods are continually being developed whereas old methods are recycled and modified. Unfortunately, many of these training methods, though having some merit, become transient trends that fail to yield quality results. Among the new training methods offering some promise is complex training (CT). CT is still being considered as a viable approach for enhancing power [1, 2]. It involves performing a resistance or weight training exercise followed shortly by a biomechanically-similar plyometric exercise. This particular combination is referred to as a complex pair. Training of this nature has become popular in recently developed programs, with one of the most well-known of these programs being CrossFit. The rationale behind CT is based on the theory of postactivation potentiation (PAP), which describes the enhanced neuromuscular state observed immediately after a session of heavy resistance exercise [3]. If biomechanically similar explosive power exercises are performed while the muscles are in this potentiated state, an individual may see an increase in both acute and chronic performance [1, 2]. Therefore, CT provides a channel for eliciting PAP. * Corresponding author. A common example of how this is accomplished is by performing a 2 6 repetition maximum (RM) squat, followed within a few minutes by a vertical jump or series of vertical jumps. The challenge, however, is finding the point at which PAP is at its highest [3]. Fatigue makes this difficult to achieve. It can coexist with PAP and may inhibit its exploitation [4, 5]. If fatigue is too great, such as immediately after the heavy resistance exercise is performed, then PAP cannot have optimal effects [3]. If too much time passes, fatigue is lessened but so are the effects of PAP. Another factor which may affect PAP that has not received much attention is the demands of the exercises in the complex pair. The majority of the research on CT utilized a protocol involving a strength exercise followed by a power exercise [1, 3, 6 12]. However, few studies have been conducted using an initial power exercise instead of the more often used strength exercise in the complex pair [13 15]. Therefore, the purposes of this study were to examine the effects of CT on lower body power as measured by vertical jump performance and to investigate whether or not the nature of the first exercise, strength (e.g. squat) or power (e.g. kettlebell swing), affected PAP and performance. Material and methods University IRB approval was obtained before proceeding with this study. Thirty-six recreationally trained (in- 141

18 C.E. Smith, B. Lyons, J.C. Hannon, Two different complex training protocols volved in 60 min of moderate-to-vigorous physical activity, 3 5 days a week for the last 3 months) men and women aged years participated in the study. The participants were recruited from a physical education course held at a Southwestern United States college. Each participant provided both written and oral consent before engaging in the study. The participants were required to complete a screening questionnaire. The first portion of the questionnaire included questions to determine the physical readiness of each individual to participate in the study (Physical Activity Readiness Questionnaire); the second portion included questions regarding nutrition and supplement intake. All participants needed to be free of injury in the preceding 3 months. Participants were excluded if they had taken ergogenic aids (e.g. anabolic steroids, growth hormone, or any performance-enhancing drugs). Participants were allowed to continue with the study if they were taking, or had previously taken, vitamins or mineral supplements. The sample was randomly assigned to three groups (each with 12 participants): squat and countermovement squat jumps (SSJ), kettlebell swings and countermovement squat jumps (KSJ), and a control group (CON). Vertical jump performance was assessed using a Vertec measurement apparatus [16] and follows a similar model used by the National Strength and Conditioning Association [17]. Prior to testing, each participant conducted a dynamic warm-up consisting of the following exercises: walking superman stretch (posterior chain), lunge walk w/twist, lateral lunge walk, walking knee lift, quad stretch, leg swings, calves stretch, and arm swings. After performing the warm-up, the reach height of each participant was obtained by keeping the shoulders square and the reach arm (chosen by the participant being tested) was extended straight upward. Standing reach was subtracted from the highest of the participant s respective vertical jump attempts to determine vertical jump height. No approach steps were permitted but a countermovement jump was used prior to takeoff. Each of the participants completed a minimum of three jump attempts although the participants were not limited to three jumps if they continued to improve. Rest periods between jumps were determined by the participants perceived readiness and lasted approximately 30 s to 2 min. Testing for each participant was completed within 15 min or less. The highest vertical jump measure of each participant was used for data analysis. The study protocol involved one preliminary screening session, the intervention (6 weeks of complex training held three times per week for the SSJ and KSJ groups), and one post-test session. The preliminary screening included the previously mentioned questionnaires and a pre-test assessment of vertical jump performance (Figure 1). Participants assigned to the SSJ group were tested for 1RM squat in order to ensure that at least 75 85% of Figure 1. Preliminary Testing and Screening Figure 2. Squat depth 1RM is used as a preload for the complex sets [2, 18]. The participants were required to squat to a depth in which the top of the quadriceps were parallel with the floor (Figure 2). If during the 6 weeks of training a participant progressed and became capable of lifting 85% 1RM for more than six repetitions, the number of repetitions was then increased to eight. If lifting the weight at eight repetitions was found to be too easy, 5 kg were added and the repetitions dropped to four and six. Participants assigned to the KSJ group were also tested if they were capable of swinging a kettlebell of at least 20 kg for four to six repetitions. Participants in this group were required to swing the kettlebell so that the handle reached at least the clavicle during the four to six repetitions (Figure 3). If during the 6 weeks of training a participant was capable of lifting a heavier weight, the load was increased by at least 4 kg (the maximum weight recorded in the study was 36 kg). The 6 weeks of CT performed by the SSJ and KSJ groups involved 18 sessions that were held three times per week on non-consecutive days. Each session lasted approximately 30 min. All three groups (CON, SSJ, and KSJ) were required to maintain the same level of physical activity throughout the 6 week period as they 142

19 C.E. Smith, B. Lyons, J.C. Hannon, Two different complex training protocols Figure 3. Approximate kettlebell swing height had for the 3 months prior to the start of the study. Participants were allowed to miss no more than two nonconsecutive training days. Missing two consecutive training sessions or more than two nonconsecutive training sessions resulted in dismissal from the study. The protocol for the training sessions involved a dynamic warm-up and three CT sets. The dynamic warm-up consisted of the following exercises: walking superman stretch (posterior chain), lunge walk w/twist, lateral lunge walk, walking knee lift, quad stretch, leg swings, calves stretch, and arm swings. Both groups were also allowed a warm-up set of their respective exercise, as needed, before beginning the three complex sets. Four to six squat repetitions were performed in the SSJ group followed by five consecutive countermovement squat jumps. In the KSJ group, four to six repetitions of kettlebell swings were performed followed by five consecutive countermovement squat jumps. A recovery period of 3 min between the resistance training exercise (squats/ kettlebell swings) and the plyometric exercise (countermovement squat jumps) was provided to allow for phosphocreatine resynthesis [7, 9, 19, 20] (Figure 4). At the cessation of the 6-week training, all participants (CON, SSJ, and KSJ) were post-tested for vertical jump performance. Overall test results were utilized to determine if CT had potential as an effective training strategy for enhancing lower body power and also to determine if the nature of the first exercise within a complex set (strength vs. power) affects the efficacy of this training. Statistical analysis for the collected data was conducted using SPSS software ver [21]. Repeated measures ANOVA (3 2 factorial design) was used to test differences in pre- and post-measures of vertical jump height. An alpha value of 0.05 was selected in the data analysis. Results Figure 4. Complex Training sessions used in the SSJ and KSJ groups Of the three groups in the study, only eight subjects completed the training session in the SSJ group, eleven in the KSJ, and nine in CON group. In the SSJ group, one participant sustained an injury outside of the study and was unable to complete the program. The remainder of the subjects were excluded from the study due to low participation. A statistical analysis was run on the pre-test measures, confirming there were no statistically significant differences between groups. The results of this study revealed a statistically significant main effect difference in pre post vertical jump measures (F = 26.19, p <.001, pre-test mean: 53 ± 11.2; post-test mean: 57.3 ± 12.6). As demonstrated in Table 1, participants in the SSJ, KSJ, and CON groups improved by a mean 5.72 cm, 4.62 cm, and 2.11 cm, respectively. However, the results also indicated there were no statistically significant differences between group vertical jump scores across time (p = 0.215) for all three groups. However, the results did suggest that the training improvements were practically significant between the SSJ and CON groups as 143

20 C.E. Smith, B. Lyons, J.C. Hannon, Two different complex training protocols Table 1. Descriptive statistics for pre- and post-mean vertical jump heights, % improvement, and vertical jump differences well as between the KSJ and CON groups (ŋ 2 p = 0.12, Figure 5). This fits within the criteria for practical significance as explained by Tolson [22]. Cohen s f statistic for the group time analysis was 0.35 (ŋ 2 p = 0.12). Further examination of the results revealed low power (0.312), most likely due to the low number of participants in the study. Discussion Group Vertical jump pre-test Vertical jump post-test % improvement Difference (cm) (cm) (cm) (cm) SSJ 55.6 ± ± KSJ 50.3 ± ± CON 53.1 ± ± Figure 5. Complex training effects on vertical jump height The purpose of this study was twofold. First, the study was designed to determine if lower body power could be enhanced using CT protocols. Second, this study investigated whether the inclusion of a power exercise instead of a strength exercise as the first exercise in the complex set would produce differences in lower body power. The results of this study revealed a statistically significant difference in pre post vertical jump scores in all three groups. The improvement of the SSJ group as a result of 6 weeks CT is in agreement with previous research [1, 3, 6 9, 11, 12, 15, 23 25]. For instance, MacDonald, Lamont, and Garner [8] found a significant improvement in vertical jump measures after 6 weeks of complex training in recreationally-trained males. Mihalik et al. [23] reported similar results in male and female club volleyball players after only 4 weeks of training. To the authors knowledge, no research had been previously conducted using kettlebell swings as part of a complex training method, and the improvements observed in the KSJ group warrant further study. Why the CON group saw significant improvements in pre post vertical jump scores is not entirely clear. It is possible that the participants in the CON group were more familiar and comfortable during the post-test assessment and this testing effect had some influence on the final result. While there was a significant difference for each group from pre-to-post testing, no statistically significant difference was found between the SSJ, KSJ, and CON groups vertical jump scores across time. Due to this result, it remains unclear whether there is any difference if the first exercise in a complex set is a squat or kettlebell swing. It is likely that with a higher number of participants in each group (e.g. n = 18 per group), there may have been different results. Figure 5 also suggests a trend for establishing statistical significance between groups over time had the study been carried out for a longer period. From a practical standpoint, it appears that the results of the SSJ and KSJ groups are more favorable than those of the CON group as they improved, on average, by 5.72 cm and 4.62 cm, respectively, when compared with the CON group (2.11 cm). Furthermore, the improvements of the SSJ group appear to be more favorable than those of the KSJ group. One explanation for this result may be found when comparing the squat and kettlebell movements, squats are biomechanically more similar to the vertical jump than the kettlebell swing. Kettlebell swings rely more on the muscles of the posterior chain while the squat exercise places greater reliance on the quadriceps group. Nevertheless, it is difficult to determine how much of a factor this played in the results particularly without having enough participants or statistical significance. Experimental mortality appears to have influenced results of the study, where the study began with 36 participants and ended with 28. The SSJ group lost the largest number of subjects, and it is possible that the training was physically more challenging with this group as opposed to the KSJ and CON. However, it is unclear whether the degree of difficulty with the workouts played a role in participant attrition. The most common reason given by participants who were unable to complete the study was that they could not fit the workouts into their schedule. There are limitations in this study with regard to the pre- and post-vertical jump testing. After conducting the warm-up, the participants were not given a ceiling on the number of jumps they could attempt, only that 144

21 C.E. Smith, B. Lyons, J.C. Hannon, Two different complex training protocols they were required to complete a minimum of three. The rest period was not specifically defined and controlled, with approximate recovery time from 30 s to 2 min between attempts. In addition, some studies have suggested a rest period of 3 min between jumps in order to ensure phosphocreatine resynthesis. Future studies may benefit from using the same recovery time [10, 15]. Also of note was that each participant finished vertical jump testing within 15 min or less. This method of testing may be more applicable in real life situations where the rest period between jumps or jump attempts are not so closely scrutinized. However, due to the lack of research supporting this approach, controlling the number of jumps and rest interval length is recommended in future research. In addition to using a more standardized testing protocol, researchers may consider using other methods of assessing vertical jump besides the Vertec. Although this device is commonly used in research studies, it has its weaknesses as a testing instrument [26 29]. Future studies might benefit from using videography in addition to the Vertec, as well as providing a familiarization session for vertical jump testing [30]. Conclusions Although the study presented a relatively basic pilot study, it provides useful information on the design of future research. The results indicate that such a complex training protocol can potentially increase lower body power. In addition, the results reveal a trend suggesting that the training improvements were greater for both the SSJ and the KSJ groups compared with CON group. While significance was not reached in this regard, the SSJ and KSJ groups improved 171% and 107% more than the CON group, respectively. Due to the observed trend, a replication of this study with a greater number of participants over a longer period of time is warranted. References 1. Bogdanis G.C., Tsooukos A., Veligekas P., Tsolakis C., Terzis G., Effects of muscle action type with equal impulse of conditioning activity on postactivation potentiation. J Strength Cond Res, 2014, 28 (9), , doi: /JSC Docherty D., Robbins D., Hodgson M., Complex training revisited: A review of its current status as a viable training approach. Strength Cond J, 2004, 26 (6), Robbins D., Postactivation potentiation and its practical applicability: a brief review. J Strength Cond Res, 2005, 19 (2), Hodgson M., Docherty D., Robbins D., Post-Activation potentiation. Sports Med, 2005, 35 (7), , doi: / Weber K., Brown L., Coburn J., Zinder S., Acute effects of heavy-load squats on consecutive squat jump performance. 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22 C.E. Smith, B. Lyons, J.C. Hannon, Two different complex training protocols programs on vertical jump height and power output. J Strength Cond Res, 2008, 22 (1), 47 53, doi: / JSC.0b013e31815eee9e. 24. Radcliffe J.C., Osternig L.R., Effects on performance of variable eccentric loads during depth jumps. J Sports Rehabil, 1995, 4 (1), Santos E.J.A.M., Janeir M.A.A.S., Effects of complex training on explosive strength in adolescent male basketball players. J Strength Cond Res, 2008, 22 (3), , doi: /JSC.0b013e31816a59f Isaacs L.P., Comparison of the vertec and Just Jump systems for measuring height of vertical jump by young children. Percept Mot Skills, 1998, 86 (2), , doi: /pms Klavora P., Vertical jump tests: a critical review. Strength Cond J, 2000, 22 (5), Leard J.S., Cirillo M.A., Katsnelson E., Kimiatek D.A., Miller T.W., Trebincevic K. et al., Validity of two alternative systems for measuring vertical jump height. J Strength Cond Res, 2007, 21 (4), Young W., MacDonald C., Heggen T., Fitzpatrick J., An evaluation of the specificity, validity, and reliability of jumping tests. J Sports Med Phys Fitness, 1997, 37, Nuzzo J.L., Anning J.H., Scharfenberg J.M., The reliability of three devices used for measuring vertical jump height. J Strength Cond Res, 2011, 25 (9), , doi: /JSC.0b013e3181fee650. Paper received by the Editor: August 22, 2014 Paper accepted for publication: October 24, 2014 Correspondence address Chad E. Smith Weber State University Health Promotion and Human Performance 1302 University Circle Ogden UT , USA chadsmith6@weber.edu 146

23 2014, vol. 15 (3), The effects of load and effort-matched concentric and eccentric knee extension training in recreational females doi: /humo James Fisher*, Christopher Langford Centre for Health Exercise and Sport Science, Southampton Solent University, Southampton, UK Abstract Purpose. The purpose of this study was to compare the effects of load and intensity of effort-matched concentric and eccentric knee extension training on isometric strength. Methods. Unilateral isometric torque was measured using a MedX knee extension after which eleven recreationally trained females performed both concentric-only (CONC) and eccentric-only (ECC) unilateral knee extension exercise once per week for 8 weeks. Participants performed a single set of both CONC and ECC exercise loadmatched at 80% of maximum isometric torque for each condition. All participants exercised to repetition maximum in both CONC and ECC conditions at a pace of ~3 s duration for each muscle action. This ensured that participants exercised to the same intensity of effort for both CONC and ECC training interventions. Results. Analyses revealed significant increases in isometric torque for both CONC (14.8%) and ECC (13.0%) conditions (p < 0.05). Absolute change from pre- to post-intervention was compared for CONC and ECC training conditions revealing no statistically significant differences (p > 0.05). Effect sizes are reported as 0.60 (CONC) and 0.53 (ECC). In addition, analyses revealed significantly greater mean total training volume for ECC compared with CONC conditions (15903 vs. 8091, respectively; p < 0.001). Conclusions. The present findings indicate that, when matched for intensity of effort, both CONC and ECC knee extension exercise can significantly improve strength to the same extent. This supports previous research that load and repetitions are not as important as intensity of effort in resistance exercise. Key words: resistance exercise, isometric, repetition maximum, unilateral training Introduction The health benefits of resistance training (RT) have been well documented [1, 2]. It is generally considered the most effective way to increase muscular strength [3] and size [4], which in turn can reduce risk of all-cause mortality [5]. Whilst the American College of Sports Medicine have previously recommended specific load and repetition ranges as optimal for increasing strength [6], recent reviews have reported that the evidence does not support a particular load or repetition range and that equivocal results can be obtained so long as persons train to a high intensity of effort, e.g. momentary muscular failure (MMF) [3]. Human movement is made possible by the relative contributions of eccentric (ECC), isometric (ISO) and concentric (CONC) muscle actions. However evidence has suggested that persons are 20 60% stronger through ECC compared with CONC actions [7, 8] and, as a result, that CONC actions require greater motor unit recruitment and muscle fibre activation than ECC actions [9]. Since observing this disparity in strength, many research studies have considered the training effects of different muscle actions. Whilst some research using isokinetic dynamometers has suggested favourable results for ECC compared with CONC training [10, 11], * Corresponding author. we should be cautious to consider the practicality of isokinetic training. An isokinetic ECC action might best be thought of as an intended CONC contraction by the participant, where a mechanical force decreases the joint angle whilst the participant resists this movement [4, 12]. This has previously been likened to supramaximal (e.g. > one repetition maximum [1RM]) negative repetitions and used as an advanced technique by experienced trainees [4]. Since supramaximal training holds inherent risks (e.g. training with a load that a person is unable to lift) and isokinetic equipment is not accessible to many trainees, we should consider a more pragmatic approach to isoinertial exercise. Surprisingly, there is limited research that has compared CONC and ECC training for the knee extensors using load and intensity-of-effort matched isoinertial contractions. Multiple studies have considered training conditions with a heavier load for ECC compared with CONC training. For example, Jones and Rutherford [7] considered ISO strength following unilateral isoinertial training with 80% 1RM for CONC and 145% 1RM for ECC training. Their results reported no statistically significant differences in strength gains between conditions. However, we might consider that whilst volume-matched, the conclusions are limited by conditions that were not equated for load or intensity of effort. Pavone and Moffat [13] also compared ISO strength following 6 weeks of either CONC or ECC training, reporting no significant differences between training groups. However, once again training load varied between CONC and ECC groups 147

24 J. Fisher, C. Langford, Concentric and eccentric training according to respective CONC and ECC 10RM tests. Finally, Smith and Rutherford [14] compared unilateral CONC and ECC training in untrained males (n = 5) and females (n = 5), reporting significantly greater strength increases for CONC compared with ECC training. This is in spite of accentuating the ECC actions by increasing the load by 35% compared with the CONC training load. This appears to be a volume-matched study and, as such, we cannot equate intensity of effort between conditions. It might be possible that intensity of effort was greater in the CONC group despite the heavier load used for the ECC condition. A further study compared multiple training conditions including load and volume matched CONC and ECC training [15]. The authors reported no significant differences in strength increases between CONC and ECC groups. However, we cannot be certain that both conditions trained at the same intensity of effort. Groups matched for load and volume likely allowed persons performing ECC-only actions to exercise at a lower intensity of effort. Perhaps the most appropriate example considered isokinetic training; Moore et al. [16] compared nine young males performing unilateral CONC and ECC training matched for both intensity of effort (maximal contractions) and total external work. They reported no significant difference in strength increases between conditions. However, this study considered the use of isokinetic training which, as discussed, is limited in practicality. The present body of literature is equivocal with regard to the efficacy of CONC and ECC training and no research to date was found which compared isoinertial CONC and ECC training with load-matched groups, where repetitions are manipulated to equate intensity of effort. With this in mind the present study aimed to compare the effects of 8 weeks of unilateral CONC or ECC knee extension exercise with equated loads performed to repetition maximum (RM). Material and methods The present study aimed to compare the effects of an 8-week unilateral CONC or ECC knee extensor RT programme performed at identical training loads. To avoid bias as a result of individual responses to training, we used a within-subject research design, where participants trained one leg CONC and ECC with the contralateral leg at an identical load. As such, the study could not be biased by differing inter-person responses to training as a result of genetics or other factors. This methodological approach is well represented in previous research [14, 17 18]. Following approval from the relevant ethics committee, 11 recreationally trained female participants were recruited and completed written informed consent (see Table 1 for participant characteristics). All participants were currently active but performed no structured resistance exercise programme. Power analysis Characteristic Table 1. Participant Characteristics (Mean ± SD) Age (years) 22.5 ± 4.1 Height (cm) ± 5.4 Body mass (kg) 58.8 ± 6.7 BMI 21.5 ± 2.8 of previous research was conducted to determine participant numbers (n) using an effect size calculated using Cohen s d [19] of 1.4 [20]. Participant numbers were calculated using equations from Whitley and Ball [21], revealing a required 8 participants to meet a power of 0.8 at an alpha value of p 0.05 for detecting strength changes. Maximum isometric knee extension torque was measured unilaterally using a MedX (USA) knee extension/flexion ergometer pre- and post-intervention, not less than 48 h following the final training session. The methods used have been described in a previous publication [22]. However, succinctly, following a dynamic bilateral warm-up at ~28kg using a 2-s CONC, 1-s ISO, and 4-s ECC repetition duration, participants performed three practice unilateral isometric tests at an estimated 50% of maximal effort. Each participant then performed maximal unilateral isometric tests at seven joint angles throughout the range of motion (96, 78, 60, 42, 24, 6 of knee flexion). For each maximal isometric contraction participants were requested to build up to maximal force over 2 3 s and were provided with ~10 s rest between test angles. The torque produced was measured by a load cell attached to the movement arm. Following testing participants were asked to identify their dominant and non-dominant leg for assignment in to CONC and ECC training groups, respectively. Unilateral knee extension training was performed on the same MedX device used in testing. All participants performed a single set of unilateral CONC and ECC knee extension exercise at 80% of their maximum tested functional torque (TFT) once a week for 8 weeks. Whilst this might appear a low volume/frequency of exercise, previous research has reported significant strength increases in isolated movements from this volume/frequency [23]. The CONC limb was trained first, performing only the CONC phase of each repetition at a 3 s duration with a research assistant performing the ECC phase of each repetition. Participants were asked to perform the repetitions until they could no longer maintain the required cadence (e.g. RM). After 3 5 min rest, participants then performed ECC repetitions only with their contralateral limb, once again at a 3 s duration, with the research assistant performing the CONC phase of each repetition. As previously, participants were asked to perform repetitions until they could not lower the load at the required cadence (RM). Once the participant could 148

25 J. Fisher, C. Langford, Concentric and eccentric training perform more than 12 CONC repetitions the load was increased by 5% for the next exercise session for both CONC and ECC exercise to maintain parity in the load between CONC and ECC training conditions. Verbal commentary during any testing/training was restricted to coaching guidance of technique rather than encouragement of performance. Isometric force data was considered as SI provided by MedX clinical equipment. This has been reported previously [23], where SI represents the area under a force curve created in each isometric test and accommodates potential increases or decreases throughout the entire strength curve for all seven test positions. This negates biasing data by seeking an average increase or decrease or only considering specific joint angles. All pre- and post-test data were analysed using SPSS ver. 20 (IBM, USA) and checked for normal distribution using a Kolmogorov Smirnov (K S) test. A two-way repeated measures analysis of variance (ANOVA) was used to examine the effects of the two independent variables condition (CONC and ECC) and time (Pre and Post) upon the dependent variable of isometric strength expressed as SI. Finally, since evidence has shown that persons are 20 60% stronger during ECC actions compared with CONC actions, a paired samples t-test was also performed to compare mean total training volume (load repetitions; TTV) for the duration of the intervention between CONC and ECC conditions. The level of significance was set to p < 0.05 in all cases. Effect sizes were calculated based on Cohen s d [19]. Results A K S test confirmed normal distribution of data for the pre- and post-intervention tests and absolute change for the isometric torque SI values (p > 0.05). The two-way repeated measure ANOVA revealed a significant within subject effect for time only (F(1,10) = , p = 0.001). Figure 1 shows pre- and post- values for SI for both CONC (pre- = 7353, ± 1598 to post- = 8442, ± 1805; 14.8%) and ECC (pre- = 7386, ± 1848 to post- = 8349 ± 2059; 13.0%) conditions. Both within subject effects for condition and interaction of condition x time were not significant (respectively, F(1,10) = 0.037, p = and F(1,10) = 0.441, p = 0.522). Effect sizes for CONC (0.60) and ECC (0.53) training were calculated, revealing moderate effect sizes [19]. A Pearson productmoment correlation coefficient was also computed to assess the relationship between CONC and ECC SI values pre- and post-intervention for all participants. There was a positive correlation between both CONC and ECC conditions (r = 0.70, p = 0.017). The paired samples t-test revealed a significant difference in TTV between the CONC and ECC conditions (t(10) = 9.170, p < 0.001; ECC = ± 3316, CONC = 8091 ± 1292). * Significant difference (p < 0.05) to pre-intervention values for relative training condition Figure 1. Mean pre- and post-intervention SI values for CONC and ECC training; error bars represent SD Discussion The purpose of the present study was to consider isometric strength improvements as a result of load and intensity-of-effort matched CONC or ECC unilateral knee extension resistance training. The data revealed significant strength increases in both CONC and ECC training with no significant differences in absolute change between conditions. Previous reviews have suggested that training with heavier loads does not incur greater strength or hypertrophic increases than training with lighter loads when training to a high enough intensity of effort (e.g. RM, MMF, etc.) [3, 4]. With this in mind and since previous research has suggested that ECC muscle actions are 20 60% stronger compared with CONC actions [7, 8], the present study used load-matched groups where participants trained to RM. Data analysis revealed significantly greater mean total training volume for ECC compared with CONC conditions (15903 vs. 8091, respectively), supporting the idea of greater strength of a muscle when performing ECC actions. Previous research considering isoinertial training with equated load and training volume has reported similar strength increases between CONC and ECC training [15], whilst other studies with a greater ECC (compared with CONC) load also reported statistically similar results [7, 13]. However, to date, the present study appears to be the only experiment which has considered load and intensity-of-effort matched isoinertial unilateral training to RM in recreational females. The results suggest that, even when the load is equated between ECC and CONC groups, the additional repeti- 149

26 J. Fisher, C. Langford, Concentric and eccentric training tions performed by the ECC group as a result of training to RM allowed intensity of effort to be matched between groups. As such, our results support previous research which has reported statistically similar results between CONC and ECC training groups performing isoinertial exercise [7, 13, 15]. However the data from Ben-Sira et al. [15] suggests a trend toward greater strength increases for CONC compared with ECC training (effect size = 0.99 and 0.80, respectively), likely as a result of load and volume but not intensity-ofeffort matched training conditions. Indeed, the data from Jones and Rutherford [7] also showed a trend toward greater gains for CONC compared with ECC training conditions (effect size = 0.65 and 0.44, respectively) even with a greater load for ECC training. This might be a result of not equating intensity of effort between groups. Since participants in the present study trained to condition-matched intensity of effort (RM), the present data supports previous reviews [3, 4] that load and volume are of less significance to muscular adaptation than intensity of effort, even when considered for differing muscle actions. In addition, since previous research has reported favourable gains for CONC compared with ECC training, even where ECC load was 35% greater than CONC [14], we can further consider the importance of training to a high intensity of effort rather than increased load, irrespective of muscle action. Further research might consider a methodological design to test this by comparing conventional (CONC + ECC), CONC and ECC repetitions with the caveat that all groups exercise to RM. Conclusions Practical applications from the present study suggest that eccentric-only repetitions are an efficacious method of improving strength when performed at a repetition duration that maintains muscular tension and to a high enough intensity of effort. This presents an alternative to conventional- or concentric-only training and might suit persons suffering from orthopaedic injury preventing concentric training. Whilst the direct applications from the present study are not extensive, we should consider that the data presented support previous publications that have reported similar muscular/neural adaptations between groups training at different loads/repetitions ranges but matched for intensity of effort. Practically, we may consider the relative limitations of performing eccentric-only exercise where it might be necessary to perform significantly greater total training volume for equivocally the same results. However, the authors contest that, whilst potentially limited in application, the present study presents important conclusions with regard to intensity of effort, load, repetitions, muscular actions and chronic muscular adaptations. References 1. Phillips S.M., Winett R.A., Uncomplicated resistance training and health related outcomes: Evidence for a public health mandate. Curr Sports Med Rep, 2010, 9 (4), , doi: /JSR.0b013e3181e7da Westcott W.L., Resistance training is medicine: Effects of strength training on health. Curr Sports Med Rep, 2012, 11 (4), , doi: /JSR.0b013e31825dabb8. 3. Fisher J., Steele J., Bruce-Low S., Smith D., Evidence-based resistance training recommendations. Med Sport, 2011, 15 (3), , doi: /v x. 4. Fisher J., Steele J., Smith D., Evidence-based resistance training recommendations for muscular hypertrophy. 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27 J. Fisher, C. Langford, Concentric and eccentric training with maximal shortening or lengthening contractions when matched for total work. Eur J Appl Physiol, 2012, 112 (4), , doi: /s x. 17. Seger J.Y., Thorstensson A., Effects of eccentric versus concentric training on thigh muscle strength and EMG. Int J Sports Med, 2005, 26 (1/02), 45 52, doi: /s Alegre L.M., Aguado X., Rojas-Martin D., Martin-Garcia M., Ara I., Csapo R., Load-controlled moderate and high-intensity resistance training programs provoke similar strength gains in young women. Muscle Nerve, 2014, Accepted Article, doi: /mus Cohen J., A power primer. Psychol Bull, 1992, 112 (1), , doi: / Nogueria A.D.C., Vale R.G.D.S., Colado J., Tella V., Garcia-Massó X., Dantas E., The effects of muscle actions upon strength gains. Hum Mov, 2011, 12 (4), , doi: /v Whitley E., Ball J., Statistics review 4: sample size calculations. Crit Care, 2002, 6, , doi: /cc Starkey D.B., Pollock M.L., Ishida Y., Welsch M.A., Brechue W.F., Graves J.E. et al., Effect of resistance training volume on strength and muscle thickness. Med Sci Sports Exerc, 1996, 28 (10), Fisher J., Bruce-Low S., Smith D., A randomized trial to consider the effect of Romanian deadlift exercise on the development of lumbar extension strength. Phys Ther Sport, 2013, 14 (3), , doi: /j.ptsp Paper received by the Editor: June 5, 2014 Paper accepted for publication: October 24, 2014 Correspondence address James Fisher Centre for Health Exercise and Sport Science Faculty of Business Sport and Enterprise Southampton Solent University East Park Terrace SO14 0YN Southampton, UK james.fisher@solent.ac.uk 151

28 2014, vol. 15 (3), Effect of resistance tube exercises on kicking accuracy, vertical jump and 40-yard technical test in competitive football players an experimental study doi: /humo Alekhya Tirumala*, Basavaraj Motimath Sports Physiotherapy Department, KLE University Institute of Physiotherapy, Belgaum, Karnataka, India Abstract Purpose. Kicking, jumping and agility are important skills in football. These activities require adequate lower limb strength, which can be enhanced with resistance training. The objective of the study was to evaluate the effect of resistance tube exercises on kicking accuracy, vertical jump performance and 40-yard technical test results in competitive football players. Methods. The study involved 23 competitive football players (11 males, 12 females) aged from years recruited from three different universities in Belgaum, Karnataka, India. Back heel kick accuracy, vertical jump height and 40-yard technical test time were evaluated before and after a 2-week resistance tube exercise program. Results. Significant improvements in post-intervention kicking accuracy were found when males and females were treated as a single group (p = 0.01). Vertical jump height also showed a highly significant post-intervention improvement in the males and for the combined group of males and females (p = 0.001). The 40-yard technical test values significantly improved in the females and in the combined results for males and females (p = 0.001). Conclusions. The two-week resistance tube exercise program was found to have an effect on kicking accuracy, vertical jump height and 40-yard technical test performance in competitive football players. Resistance tube exercises can thus be included as a component of a regular strength training program for such athletes. Key words: resistance training, resistance tubing, back heel kick, performance, agility Introduction Football is one of the oldest and most popular sports in the world, with around 150 football-playing countries. In 1984, it was estimated that 60 million players were licensed whereas another 60 million were unlicensed, with the latter group consisting of youth and recreational players involved in local football leagues [1]. In 2006, it was estimated that 265 million males and females (including 5 million referees), or about 4% of the world s population, were actively involved in football [2]. In India, football has been gaining popularity throughout the country irrespective of a lack of investment and proper planning. As a team sport, football has a highly intermittent and unpredictable activity pattern [3]. It is considered to be sport dominated by randomized, intermittent, dynamic and skilled movement [4]. A study comparing the distances covered on the field in different team sports found a professional male or female football player to cover km per game, considerably more than other team games [5, 6]. The physical fitness level of football players is crucial as it determines both game efficiency and tactical performance [7]. On the field, football requires explosive bursts of energy in the form of sprinting, jumping, kicking, changing directions and maintaining balance [8]. To attain an appropriate fitness level for such * Corresponding author. tasks, it is recommended that players train according to the demands of the game [9]. As such, a football training program should improve performance by inducing adaptations in the neuromuscular system, whereas the level of this adaptation depends on the type of training program [10]. One of the more important components of physical fitness in football is strength, as it determines the performance of numerous on-field physical tasks and movements. The US National Strength and Conditioning Association states that besides strength, the advantages of strength training in football include increased local power and endurance and improved performance in the sport [10]. One of the most important and widely used skills in football is kicking [11], as it is used to deliver the ball over a desired distance to an intended target [12]. The effectiveness of a smooth kicking action depends on various factors, including the maximal strength of the involved muscles, neuromuscular coordination, rate of force development and the level of coordination between muscle agonists and antagonists [13]. Furthermore, the final stage of kicking, when the knee is extended, requires maximal force production and strength from the hamstrings and quadriceps [14]. Among the various types of kicks, one kick worthy of mention is the back heel kick. It can be used in a regular pass and also as a penalty kick [15]. This kick can be as effective as any other, especially in deceiving an opponent as it is so unexpected [16]. Regardless of the type of kick used, the importance of maximal strength for power production in kicking has been highlighted by Haghighi et al. [17]. 152

29 A. Tirumala, B. Motimath, Improving football performance Although there have been studies examining the effect of strength training on kicking performance, the results are inconsistent. On the field, apart from kicking, jumping ability is also an important component of football. The literature reveals that jumping ability depends on inter-limb coordination, muscle fibre type and muscle strength [18]. Studies have shown that vertical jump height improves through training interventions involving jumping exercises, plyometric exercises, depth jumps and resistance training. Another important component of football is agility, used to outmanoeuvre the opposition and also protect players from injury. According to Sporis et al. [12], agility is the ability which helps the athlete change directions, make quick stops and perform fast and smooth repetitive movements. Several factors are known to affect the level of agility, some of them being joint mobility, flexibility, dynamic balance, power, energy resources and muscle strength. Certain studies have shown the positive results of plyometric training on both vertical jump height and agility [12], also stating that both maximal jumping and sprinting are considered to be dynamic movements requiring high muscle power and should therefore be closely related. The literature suggests that increasing the force of muscular contraction in appropriate muscle groups results in increased acceleration and speed and is therefore critical in the previously-mentioned components of agility, including turning, sprinting and changing directions and pace [4]. Resistance tubes or elastic tubes have been commonly employed in resistance training. The basic difference between resistance tubes and other forms of resistance training is that tubes are used to generate a controlled and consistent force depending on the needs of the individual. The tubing provides a resistive force during exercise with a low or high load stretch [19]. They are made of natural rubber latex and are available in progressive levels of resistance (yellow, red, green, blue, black and silver, respectively). A manufacturer of resistance tubing, the Thera-Band Academy, cites numerous studies on their effectiveness in improving strength, mobility and function [20]. A study on elderly individuals suggests that such tubes have a positive impact on improving muscle power, balance and body composition [21]. However, little information on the effect of resistance tube exercise in young individuals was found. Additionally, there is a paucity of literature on the effect of resistance tube exercises on football performance. While there exist numerous studies analysing the effect of resistance exercises on football performance, there is a lack of general information on the effect of resistance training on kicking accuracy [18]. Some authors have found that plyometric training improves kicking performance as it induces neuromuscular adaptations to the stretch reflex. Others have reported a positive effect of resistance training combined with plyometric exercises in enhancing vertical jump height [22]. However, research on the effect of resistance exercises using only resistance tubing is lacking. There is also a dearth of data on resistance training involving resistance tubes for the enhancement of agility in football players. Hence, the present study was undertaken to analyse all of the above factors and add to the literature on the effects of resistance training using resistance tubes and analyse its impact on kicking accuracy, vertical jump height and agility as measured by the 40-yard technical test in a group of football players. It was hypothesised that resistance tube exercises would improve all three tested variables. Material and methods After attaining approval from the Institutional Ethical Committee at the KLE University Institute of Physiotherapy, 25 competitive football players (13 males, 12 females) were recruited using convenience sampling from three different universities in Belgaum, Karnataka, India (Gogte College of Commerce, GSS College of Science and KLE University). Participants were included in the study if they were between 18 and 25 years, competed in football events, volunteered to participate in the study and were pain-free at the time of testing. Participants were excluded if they had any recent trauma to the knee, ankle or hip in the past 6 months, had a history of any recent (6 months prior) lower limb orthopaedic surgery, or sustained any injury or suffered from any medical illness during the course of the study. The purpose of the study was explained and written informed consent was obtained from all participants. Participants BMI was calculated and information on their football playing history was collected. Two of the male participants dropped out, one due to poor participation and one due to an ankle injury sustained during the study. The study was performed during the off-season, and the participants were asked to refrain from all other forms of strength training during the study duration. Measures Measures assessing back heel kicking accuracy, vertical jump height and 40-yard technical test time were collected before a resistance tube exercise program for the lower limbs was administered. All pre-intervention measures were gathered one day before the training commenced; post-intervention measures were collected one day after the training program was completed. Both pre- and post-measures were evaluated on the same field where the participants regularly practiced. Kicking accuracy was measured as per Finoff et al. [23]. The participant was asked to stand in front of a cm wide 122 cm high piece of cardboard at a distance of 20 m. Carbon paper was pasted on the 153

30 A. Tirumala, B. Motimath, Improving football performance Figure 1. Setup used to measure kicking accuracy; cardboard covered with carbon paper and marked with a bullseye cardboard (see Figure 1) and a bullseye was drawn. The participant performed five trails with the back heel kick. Deviations from the bullseye were measured using a measuring tape. The most accurate kick was considered for analysis. The vertical jump was measured as suggested by Changela et al. [24]. The participant stood against the wall with both feet on the ground and reached as high as possible with one hand; the height at the tips of the fingers was measured. The participant then bent their knees and jumped as high as possible, where the height at which tips of the fingers of the same hand reached was measured. The difference between the first height and the second height was calculated. The best result of three trials was recorded. The 40-yard technical test was performed according to the Utah Youth Soccer Association [25]. Four cones were placed on a field, where the first cone (A) represented the starting point. The second cone (B) was placed 10 yards directly in front of the first cone. The third cone (C) was placed 5 yards to the left of the second cone and the fourth cone (D) was placed 5 yards to the right of the second cone. Starting in a standing position, the participant was timed on how long it took them to sprint from cone A to cone B, then sidestep to cone C, then sprint to cone D, sidestep back to cone B, and finish with a backward sprint to cone A. leg extension, side leg raise and standing leg curl, with each exercise performed for 3 sets of 8 12 repetitions. The resistance of the tube was individually selected for each participant using the blue, black and silver colours. Difficulty was increased by increasing the resistance of the tubing and the number of repetitions as well as training on an uneven surface (side leg raise and standing leg curl). The exercises were performed as below: One-leg press The participant was asked to sit on the ground with their legs out in front of them, knees slightly bent. They were asked to hold one end of the resistance tube in each hand and place it around the sole of the right foot keeping the right knee slightly bent. They then straightened their right leg (without locking their knee) while pulling on both sides of the resistance tube. The participant continued to pull against the resistance tube as they returned to the original bent position. The exercise was then repeated with the left leg (Figure 2). Knee lift The participant was asked to sit in a comfortable position with the hip and knees perpendicular to each other. Holding the tube in their hands, the participant stretched the tube by pulling their knees in toward the chest so as to increase the resistance against their lower abs and front thighs. They then slowly returned to the starting position (Figure 3). Figure 2. One-leg press Training protocol The resistance tube exercise program lasted 2 weeks and was performed four times per week. All the participants completed a general warm up before each training session by stretching the lower limbs (hamstrings, quadriceps, calf muscles and adductors). The resistance tube exercises consisted of the one-leg press, knee lift, seated Figure 3. Knee lift 154

31 A. Tirumala, B. Motimath, Improving football performance Figure 4. Seated leg extensions Figure 5. Standing leg curls Seated leg extension The participant sat on a bench with a straight back with the feet and knees shoulderwidth apart. Holding both ends of the tube in the left hand, they were asked to slowly straighten the left knee and lift their foot until the leg was straightened (at a 90-degree angle to the torso). The participant was then asked to slowly bend the left knee and return to the starting position. The exercise was then repeated with the right leg (Figure 4). Standing leg curl Two participants were involved in this exercise. One participant held the two ends of the resistance tube that was placed around the second participant s foot. The second participant was asked to keep the knees close together and smoothly lift their right heel up toward their bottom. This exercise was then repeated with the other leg (Figure 5). Side leg raise Two participants were involved in this exercise. Both participants were asked to stand next to each other and have each place one foot on the resistance tube and the other foot at its end. The participants then lifted the leg placed in the end of the tubing straight out to the side until the foot attained a height of 15 to 30 cm off the ground. They then returned the leg to the starting position. The participants were asked to keep an erect torso throughout the movement and slightly bend the leg supporting their body. The exercise was then repeated with the other leg (Figure 6). The range of motion in the exercises was not quantified although they were performed by increasing the resistance of the resistance tube. Body position was fixed in terms of bending at the torso in the standing or sitting positions. The upper extremities holding the ends of the resistance tubes were also fixed in order to not bring any variation in the movement. The remaining body segments were allowed to remain mobile and moved according to the exercise. The length of the tube was not controlled and varied according to the needs of each participant. This was done as every participant required a different threshold of resistance to perform the exercise. Statistical analysis involved calculating the means and standard deviations of the collected data. The kicking accuracy, vertical jump and 40-yard technical test measures were compared pre- and post-intervention by the paired samples t test. Intra-group comparison between male and female participants was analysed using the unpaired form of the t test. Results Figure 6. Side leg raises on uneven surface The demographic data demonstrated that males had higher BMI and longer playing experience than their female peers (Table 1). Comparisons of pre- and post-intervention kicking accuracy values (Table 2) showed significant improvements for the combined results of both males and fe- 155

32 A. Tirumala, B. Motimath, Improving football performance Table 1. Intra-group comparisons of BMI and length of football playing career (mean ± s) BMI (kg/m 2 ) Playing career (years) Male ± ± 2.49 Female ± ± 2.69 t value p value < 0.01** < 0.01** ** indicates high significance males (p = 0.01). No statistically significant differences were noted separately for males and females (p = and p = 0.054, respectively). Intra-group comparisons between the male and female participants (Table 3) did not show any statistically significant differences pre-intervention (p = 0.94) and post-intervention (p = 0.59). The combined (male and female) pre- and post-intervention vertical jump values (Table 2) showed a significant enhancement (p = 0.001). The male participants showed a higher statistically significant improvement (p = 0.001) compared with the female participants. Intragroup comparisons between the male and female participants (Table 3) showed statistically significant differences post-intervention (p = 0.01) The results for the 40-yard technical test showed statistically significant improvements (Table 2) pre- and post-intervention (p = 0.001). The male and female participants also showed significant improvements (p = 0.01 and p = 0.001, respectively). Intra-group comparisons (Table 3) showed significant differences in the results pre- and post-intervention (p = 0.01). Discussion The present study used resistance tubes in a twoweek resistance training intervention for competitive football players. Its purpose was to see the effects of resistance tube exercises on kicking accuracy, vertical jump height and 40-yard technical test time pre- and post-intervention, with the results finding significant improvements in all three measures. Table 2. Comparison between pre- and post-intervention kicking accuracy, vertical jump height and 40-yard technical test time (mean ± s) Measures Pre-intervention Post-intervention Difference t value p value Cohen s d Kicking accuracy (cm) Male ± ± Female ± ± Combined ± ± < 0.01** 0.55 Vertical jump (cm) Male ± ± < 0.001*** 1.63 Female ± ± Combined ± ± < 0.001*** yard technical test (s) Male ± ± < 0.01** 0.57 Female ± ± < 0.001*** 0.99 Combined ± ± < 0.001*** 0.62 ** indicates high significance, *** indicates very high significance Table 3. Intra-group comparisons of kicking accuracy, vertical jump height and 40-yard technical test times between the male and female participants (mean ± s) Measure Male Female t value p value Cohen s d Kicking accuracy (cm) Pre-intervention ± ± Post-intervention ± ± Vertical jump (cm) Pre-intervention ± ± Post-intervention ± ± < 0.01** yard technical test (cm) Pre-intervention ± ± < 0.01** 1.43 Post-intervention ± ± < 0.01** 1.3 ** indicates high significance 156

33 A. Tirumala, B. Motimath, Improving football performance In terms of kicking accuracy, the results are in disagreement with Haghighi et al. [17], who studied 30 elite football players divided into control, plyometric and resistance training groups. After training for 8 weeks, the study found that both plyometric and resistance training improved sprinting speed and dribbling performance. However, no significant improvements in terms of kicking accuracy were shown. It needs mentioning that the resistance training program in Haghighi et al. consisted of 2 4 sets of weight training exercise at an intensity of 60 90% 1-RM, whereas this study used three sets of 8 12 repetitions of resistance tube exercises for 2 weeks. In addition, their study did not mention the type of kick the players were asked to perform as a measure of kicking accuracy. One of the reasons behind the significance in our study, as suggested by Manolopaulos et al. [26], could be that the football kick utilizes the stretch-shortening cycle characteristics of the involved muscles, especially the knee extensors. In a developed kicking action, it has been found that the thigh comes forward while the knee is still flexing. This action serves to stretch the thigh extensor muscles before they need to shorten so that they are able to generate large end-point speed. Manolopaulos et al. emphasized the importance of utilizing the stretch-shortening cycle of the muscles of the kicking leg. According to their study, one of the main mechanisms that may improve kicking performance is the action of the thigh that slows down or reverses its motion prior to full knee extension. This is indicative of a more powerful shot following training. The present study used resistance tubes as a form of strength training as a way to develop strength, balance and coordination. According to a study by Patterson et al. [19], such tubing provides for controlled stretching and strengthening of muscle tendon units and joints and allows for a pre-stretching effect as well as controlled repeatability throughout the movement. This may be related to what Manolopaulos et al. [26] proposed on improving kicking performance. The standing leg curl exercise used in our study started with a concentric contraction of the quadriceps and ended with a concentric contraction of the hamstrings. It is supposed that this could have improved the back heel kick as it was specific to this type of action. The present study showed no statistically significant results in the kicking accuracy of male players and female players when analysed separately by sex. The reasons for this could be attributed to those expounded by Lyons [27], who proposed that females have weaker hamstrings in relation to their quadriceps as compared with their male counterparts. This could have been the rationale behind the lack of a significant improvement in females alone as the kicking accuracy using the back heel kick, which requires optimal strength of the hamstrings to kick the ball backwards. Another reason could be due to the training duration, where 2 weeks may not have been sufficient enough to produce a significant effect individually in the females as well as males. One other possibility for the lack of significant changes could be due to the relatively small sample size. With respect to the vertical jump, the present study showed a highly significant increase between pre-intervention and post-intervention values. Adibpour et al. [28] compared the effects of plyometric and weight training on vertical jump height in 35 female basketball players, concluding that both plyometric and weight training produced significant improvements in vertical jump height in females. The increase in vertical jump height in the present study was approximately 5.7 cm in total, or 1.3 cm less than reported by Adibpour et al, although this may stem from the fact that their study combined both plyometric exercises and weight training. In addition, the increase in vertical jump height in the above study may be attributed to the strengthening of the leg muscles, therefore boosting instant energy resources. Such an increase in muscle strength could also be the rationale for the improvements observed in the present study. The results of this study imply that vertical jump test performance increased by recruiting greater muscle mass (with both legs simultaneously working as well as the inclusion of upper-body musculature) and therefore generating significantly greater power. Additionally, greater muscle strength induced by the resistance tube exercises must have increased the ATP supply, which would lead to enhanced anaerobic power in the initial phase of any power activity, including jumping. The present study showed a significant improvement in the vertical jump height of the male football players, with a difference of at least 7 cm noted before and after the intervention. This is compared with the female football players, where a difference of only 4.5 cm was noted and which was not significant. This result could be correlated to a study done on elite male football players by Wisloff et al. [29], where it was suggested that football players should focus on developing maximal strength with a focus on concentric movements in order to improve vertical jump height. A similar conclusion can be reached in the present study, which also used maximal and controlled concentric and eccentric exercises such as the one leg press. This mid-range semi knee flexion to a full knee extension movement of the quadriceps and hamstrings may have promoted strength development in these muscle groups. The other exercises in the present study included knee lifts to strengthen the hip flexors and side leg raises to strengthen the abductors. A combined increase in the strength of these muscles might have brought about a larger coupled force and led to improved vertical jump height. The non-significant results in the female participants can again be attributed to a reduced quadriceps-to-hamstring strength ratio in comparison with their male counterparts. 157

34 A. Tirumala, B. Motimath, Improving football performance The results of the 40-yard technical test demonstrated significant improvements when comparing the combined male and female pre- and post-intervention values. Separately, both the results of the female and male participants showed highly significant improvements. This is consistent with the results reported by Taheri et al. [30], in which 30 male football players were divided into plyometric and resistance training groups and trained for 8 weeks. The resistance training group performed exercises such as the smith press, seated press, squat, leg extension, leg press, standing barbell curl, lying barbell extension, and sit up with an intensity initially at 60% of 1RM, increased by 10% every 2 weeks. The results found that the resistance training group showed better improvements in a 4 9 agility test compared with plyometric group. The investigators reasoned that muscle fibre hypertrophy induced by resistance training may have improved the ability to change position and direction rapidly without losing balance and coordination. A similar conclusion can be reached in the present study, where significant improvements were also noted for agility as measured by the 40-yard technical test. However, muscle hypertrophy alone could not have caused this improvement. as it involves at least 4 6 weeks of training according to Moritani and devries [31]. However, the 2 weeks of resistance tube training in the present study may have led to a significant improvement in muscle strength. Based on a literature review by Deschenes and Kraemer [32], the initial phase (lasting up to 4 weeks) of high volume resistance training should involve at least 3 sets of 8 12 repetitions for each exercise. This review also suggested that muscle strength significantly progresses during the first 4 weeks of resistance training and could be attributed to neural adaptations, leading to increased firing of neural impulses and therefore greater recruitment of high-threshold motor units, thus gaining strength. Resistance tubes appear to be effective in developing strength [30], balance and coordination due to the controlled movements in exercise with such tubing. The last two components can be explained by the exercises used herein, such as the side leg raise and standing leg curl, as they were performed by the participants in the standing position, with the difficulty of these exercises increased by performing them on an uneven surface. These two factors, the standing position and change in surface, are believed to have enhanced the balance and coordination components. Conclusions The results of the present study show that a 2 week resistance tube exercise program had a positive effect on back heel kicking accuracy, vertical jump height and 40-yard technical test times in competitive football players. There are nonetheless a number of limitations in the present study that should be considered. Firstly, the study involved only 23 participants, which provides a small sample size. Secondly, no follow up was performed in order to evaluate the duration of the training effects, where post-intervention measures were studied a day after the training ended. Thirdly, although the participants were asked to not partake in any other strength training during the study, the investigators had no control over any other sport activities or practice sessions the participants attended. This factor may have influenced the results. Additional studies should be pursued using a resistance tube exercise program in a larger population with a longer training duration so as to evaluate the longterm effect of such an intervention. Future research should also include additional study groups, such as a control and a group involved in a traditional resistance training program, so as to allow for a better understanding of the effect of resistance tubes alone. Finally, the back heel kick should also be taken into consideration in future studies, as an effective back heel kick can lead to improved match results. References 1. Ekblom B., Applied Physiology of Soccer. Sports Med, 1986, 3 (1), 50 60, doi: / Kunz M., 265 million playing football. FIFA Magazine, July 2007, Available from: document/fifafacts/bcoffsurv/emaga_9384_10704.pdf. 3. Mohr M., Assessment of training and game load in team sports. University of Copenhagen, Denmark. Available from: pdf 4. 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36 2014, vol. 15 (3), Oxygen consumption while standing with unstable shoe design doi: /humo Benedikt A. Gasser *, **, Adrian M. Stäuber **, Glenn Lurmann, fabio A. breil, Hans H. Hoppeler, Michael Vogt Swiss Health & Performance Lab, Institute of Anatomy, University of Bern, Bern, Switzerland Abstract Purpose. This study explored the effects of unstable shoe design on oxygen consumption. Methods. Oxygen consumption (VO 2 ) and heart rate (HR) were measured in 16 individuals while barefoot, wearing unstable shoes (Masai Barefoot Technology) and wearing conventional sport shoes while standing and walking on a treadmill and for 5 individuals while walking around a 400 m track. Results. When wearing the MBT shoes, a significant (p < 0.01) increase of 9.3 ± 5.2% in VO 2 was measured while standing quietly for 6 min. No differences in VO 2 and HR were observed between the MBT shoes or weight-adjusted conventional shoes (to match the weight of the MBT shoes) while walking on a treadmill. However, significant increases (p < 0.01) in VO 2 (4.4 ± 8.2%) and HR (3.6 ± 7.3%) were observed for the MBT shoes compared with being barefoot. No significant differences in VO 2 and HR were recorded while walking around a 400 m track either with MBT shoes, weight-adjusted conventional shoes or barefoot. Nonetheless, a comparison of the MBT shoes with barefoot revealed a tendency for VO 2 to be higher when wearing the MBT shoes (7.1 ± 6.5%, p < 0.1) although HR was not significantly affected. Conclusions. The unstable shoe design predominantly effects oxygen consumption while standing, most likely due to increased muscle activity of the lower extremities. Key words: oxygen consumption, heart rate, unstable shoe construction, MBT (Masai Barefoot Technology) Introduction Shoes affect both standing and walking [1]. They influence gait, muscle activity, balance and the pressure distribution in the sole of the foot [2 5]. The Masai Barefoot Technology (MBT) shoe has been described as a training and therapeutic shoe that can be worn during the normal course of the day [6]. The unstable nature of these shoes (Figure 1) is credited with stimulating musculature and sensorimotor activity in the lower extremities. Built into the heel is a rounded sole, the so-called Masai Sensor. It introduces a destabilising effect in the anterio-posterior direction, i.e. the frontal plane, causing a rocking motion as it is very soft and thus responsible for the instability. Additional muscular reflexes and activity compensate for this instability. According to the manufacturer, whole body posture is affected as a consequence of this design. Several research institutes (University of Calgary, Universität Freiburg im Breisgau, Universität Salzburg) have already performed a wide gamut of studies examining the effects of such unstable shoe construction on physiological and biomechanical responses. Nigg et al. [7] examined the effects of varied shoe constructions on kinetic and kinematic variables and muscle activity using EMG while standing and walking. They found that muscle activity was elevated in all muscles in the distal portion of the lower extremities, however, this result was significant only for the musculus tibialis anterior. Romkes [6] examined differences in muscle activity patterns while walking with conventional and MBT shoes. This study found changes in muscle activity patterns in the talocalcaneal joint, in particular for the musculus gastrocnemius and musculus tibialis anterior. Analysing the ability to control balance while wearing these shoes, Romkes [5] examined the time course of the foot sole s pressure points. While standing, significant differences were observed in the ability to control balance in the anterio-posterior as well as the medio-lateral directions while wearing the MBT shoes compared with being barefoot. * Corresponding author. ** Both authors contributed equally to this study. Figure 1. Construction of MBT shoe with the characteristic rounded sole, the soft sensor and harder area for balancing 160

37 B.A. Gasser et al., Shoe sole construction and oxygen consumption We are unaware of any study that has looked at differences in oxygen consumption between conventional and MBT shoes during routine everyday movements such as standing and walking. Therefore, our study was undertaken in an effort to gain better insight into energy expenditure while wearing such an unstable shoe design and formulated the following hypotheses: Increased muscle activity caused by wearing MBT shoes should lead to an increase in metabolism and heart rate when compared with conventional shoes while standing. Increased muscle activity caused by wearing MBT shoes should lead to an increase in metabolism and heart rate when compared with conventional shoes while walking. Material and methods The study hypotheses were tested in three experiments: 1) laboratory conditions while standing, 2) laboratory conditions while walking on a treadmill and 3) field conditions while walking around a 400 m running track (Figure 2) when wearing different types of shoe designs (MBT shoe, conventional shoe, weight-adjusted conventional shoe) as well as without footwear (barefoot). All participants were healthy with an average level of fitness. Ethical permission was sought and granted by the Bernese Ethics Commission. For measurements while standing, six female and ten male participants were recruited with mean age, height, mass values of 29.8 ± 6.8 years, 178 ± 7 cm and 72.3 ± 11.4 kg, respectively. Measurements while walking involved five female and eleven male participants with mean age, height and mass values of 32.8 ± 7.5 years, 173 ± 7 cm and 66.4 ± 12.4 kg, respectively. Field measurements while walking involved only five male participants with mean age, height and mass values of 29.7 ± 3.1 years, 175 ± 4 cm and 69.4 ± 8.4 kg, respectively. Laboratory measurements taken while standing included oxygen consumption (Oxycon Alpha metabolic cart, Jäger, Germany) and heart rate (RS300X, Polar, Switzerland) Participants stood quietly for 6 min in a relaxed position. Participants were instructed to stand on two marks on the floor placed 25 cm apart with feet parallel to each other. They were told to look straight ahead and keep their arms to their sides. Measurements were made while wearing the MBT shoe and conventional shoes. The order in which the shoes were worn was randomised. When wearing the MBT shoes participants were instructed to balance their weight on the rounded portion of the sole. Laboratory measurements while walking were performed on a PPS Sport treadmill (Woodway, Germany) at different speeds and inclines. Oxygen concentration and heart rate were measured continuously, with the same equipment as described above, and included the warm-up. The order of phases 1 4 was randomised: Warm-up: 5 km h 1 at no incline for 3 min Phase 1: 5 km h 1 at no incline for 6 min Phase 2: 4 km h 1 at 10% positive incline for 6 min Phase 3: 4 km h 1 at 10% negative incline for 6 min Phase 4: 7 km h 1 at no incline for 6 min The walking phases were performed wearing the MBT and conventional shoes. In this test, the weight of the conventional shoes was adjusted to equal that of the MBT shoes (± 5 g) using metal discs fixed with tape (Figure 3). The weights were fixed close to the ankle to optimise inertia and torque and allow for maximal freedom of movement. Phase 1 was also performed barefoot by all participants. Field measurements were performed on a 400 m running track (Figure 2). Analogous to Phase 1 in the walking test, oxygen consumption (K4b2 gas analysis system, Cosmed, Italy) and heart rate (RS300X, Polar, Switzerland) were measured during a 6 min walk at 5 km h 1. Figure 2. Field measurements of oxygen consumption and heart rate while walking in MBT, weight-adjusted and non-weight-adjusted conventional shoes as well as barefoot on the 400 m running track 161

38 B.A. Gasser et al., Shoe sole construction and oxygen consumption Figure 3. Weight-adjustment of conventional shoes This was performed by all participants using the MBT shoe, the weight-adjusted conventional shoe (Figure 3) and while barefoot, all in randomised order. To ensure correct walking speed, the running track was marked every 10 m and the participants were provided with an acoustic signal every 10 m to pace themselves. Their speed was subsequently verified using a GPS device. Measurement of oxygen consumption and heart rate was continuous [8]. Analysis of data was conducted using 30 s averages of oxygen consumption and heart rate. The last 2 min of each measurement phase was used for statistical analysis to ensure steady-state had been reached [9, 10]. To avoid calibration mistakes, all measurements were taken without interruption including when participants changed shoes. All statistical analyses were performed using Mathematica software (Wolfram Research, USA). The percent difference in oxygen consumption and heart rate were compared between shoe types and barefoot, when applicable, using paired two-way t tests assuming homoscedasticity. For comparisons of the MBT shoe, conventional shoe and barefoot, an analysis of variance (ANOVA) was performed and with post-hoc Scheffé tests. As mentioned, the last 2 min of each measurement phase was used for comparison. Gaussian distribution of the data was checked using the Jarque Bera test [11]. Statistical significance was accepted at p < 0.05, while values between 0.05 and 0.1 were considered to indicate a tendency. Results The first hypothesis, assessed in laboratory conditions while standing, was confirmed (Table 1). An increase in the oxygen consumption rate (Figure 4) in the order of 9.3 ± 5.2% (p < 0.01) was recorded while standing in the MBT shoes compared with conventional shoes. Heart rate (Figure 5) was not significantly different (p = 0.25). The second hypothesis, examined in laboratory conditions while walking, was not confirmed. No significant differences were observed in ANOVA while walking with the MBT, conventional shoes or barefoot (Table 1). Similarly, the second hypothesis when tested in field conditions was also not confirmed. No significant differences were noted while walking with the MBT or weightadjusted conventional shoes (Table 2). However, oxygen consumption tended to be 7.1 ± 6.5% (p < 0.1) higher when wearing the non-weight-adjusted conventional shoes and 5.9 ± 5.6% (p < 0.1) when barefoot. Heart Significant difference indicated by asterisk (p < 0.01), line in box indicates median Figure 4. Oxygen consumption while standing in conventional (354 ± 55 ml O 2 min 1 ) and MBT (387 ± 64 ml O 2 min 1 ) shoes (n = 16) No significant difference (p = 0.25), line in box indicates median Figure 5. Heart rate while standing in conventional (81 ± 11 beats min 1 ) and MBT (84 ± 14 beats min 1 ) shoes (n = 16) 162