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

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1 University School of Physical Education in Wrocław University School of Physical Education in Kraków vol. 14, number 4 (December), 2013

2 University School of Physical Education in Wrocław (Akademia Wychowania Fizycznego we Wrocławiu) University School of Physical Education in Kraków (Akademia Wychowania Fizycznego im. Bronisława Czecha w Krakowie) Human Movement quarterly vol. 14, number 4 (December), 2013, pp Editor-in-Chief Associate Editor Alicja Rutkowska-Kucharska University School of Physical Education, Wrocław, Poland Edward Mleczko University School of Physical Education, Kraków, Poland Editorial Board Physical activity, fitness and health Wiesław Osiński University School of Physical Education, Poznań, Poland Applied sport sciences Zbigniew Trzaskoma Józef Piłsudski University of Physical Education, Warszawa, Poland Biomechanics and motor control Tadeusz Bober University School of Physical Education, Wrocław, Poland Kornelia Kulig University of Southern California, Los Angeles, USA Physiological aspects of sports Andrzej Suchanowski Jozef 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 Proofreading: Beata Kanak Indexed in: SPORTDiscus, Index Copernicus, Altis, Sponet, Scopus, CAB Abstracts, Global Health 7 pkt wg rankingu Ministerstwa Nauki i Szkolnictwa Wyższego Copyright 2013 by Wydawnictwo AWF we Wrocławiu ISSN Editorial Office Dominika Niedźwiedź Wrocław, al. Ignacego Jana Paderewskiego 35, Poland, tel , hum_mov@awf.wroc.pl This is to certify the conformity with PN-EN-ISO 9001:2009 Circulation: 160

3 2013, vol. 14 (4) contents physical activity, fitness and health Agnieszka Olchowska-Kotala, Krystyna Chromik Body satisfaction and time spent on physical activity in Polish students Tomasz Boraczyński, Michał Boraczyński, Sandra Boraczyńska, Anna Michels Changes in body composition and physical fitness of 7-year-old girls after completing a 12-month artistic gymnastics training program Agnieszka Dębiec-Bąk, Katarzyna Gruszka, Krzysztof A. Sobiech, Anna Skrzek Age dependence of thermal imaging analysis of body surface temperature in women after cryostimulation Jennifer Harmon, Timothy A. Brusseau, Douglas Collier, Elizabeth Lenz Habitual physical activity patterns of inner-city children Magdalena Rokicka-Hebel Preschool attendance as a factor in the motor skill development of children biomechanics and motor control Michael G. Robinson, Laurence E. Holt, Thomas W. Pelham An assessment of hydrodynamic and simulated race performance features of three C-1 hull designs Erika Zemková, Michal Jeleň, Gábor Ollé, Tomáš Vilman, Dušan Hamar Power production during bench press with different ranges of motion on stable and unstable surfaces Jonathan Sinclair, Jack Hebron, Howard Hurst, Paul Taylor The influence of different Cardan sequences on three-dimensional cycling kinematics Daniel das Virgens Chagas, Gustavo Leporace, Jomilto Praxedes, Igor Carvalho, Sérgio Pinto, Luiz Alberto Batista Analysis of kinematic parameters of gait in Brazilian children using a low-cost procedure Rafael Pereira, Max Miller Alves Mendel, Ludmila Schettino, Marco Machado, Pierre Augusto-Silva Acute neuromuscular responses to a resistance exercise session performed using the DeLorme and Oxford techniques physiological aspects of sports Agron M. Rexhepi, Behlul Brestovci The functional efficiency of mouthguards in martial sports Piotr Makar, Grzegorz Bielec Lactate and glucose concentrations in assessing anaerobic capacity in an elite junior swimmer a case study Bartosz Molik, James J. Laskin, Andrzej Kosmol, Jolanta Marszałek, Natalia Morgulec-Adamowicz, Tim Frick Relationships between anaerobic performance, field tests, and functional level of elite female wheelchair basketball athletes Publishing guidelines Regulamin publikowania prac

4 2013, vol. 14 (4) editorial We would like to express our deepest gratitude to all Reviwers for their most effective contribution to the improvement of quality of Human Movement in 2013: William M. Bertucci, Reims (France) Rodrigo Rico Bini, Porto Alegre (Brazil) Jan Blecharz, Kraków (Poland) Tadeusz Bober, Wrocław (Poland) Eugeniusz Bolach, Wrocław (Poland) Zbigniew Borysiuk, Opole (Poland) Janusz Brudecki, Kraków (Poland) Piotr Brzozowski, Lublin (Poland) Jadwiga Charzewska, Warszawa (Poland) Loren Z.F. Chiu, Edmonton (Canada) Krystyna Cieślik, Poznań (Poland) Stanisław Czyż, Wrocław (Poland) Jacek Dembiński, Wrocław (Poland) Henryk Duda, Kraków (Poland) Włodzimierz S. Erdmann, Gdańsk (Poland) Sean Flanagan, Los Angeles (USA) Jan Gajewski, Warszawa (Poland) Krystyna Górna-Łukasik, Katowice (Poland) Jan Górski, Białystok (Poland) Halina Guła-Kubiszewska, Wrocław (Poland) Rami Hashish, Los Angeles (USA) Zofia Ignasiak, Wrocław (Poland) Janusz Iskra, Katowice (Poland) Grzegorz Juras, Katowice (Poland) Katarzyna Kisiel-Sajewicz, Wrocław (Poland) Krzysztof Klukowski, Warszawa (Poland) Leszek Korzewa, Wrocław (Poland) Stanisław Kowalik, Poznań (Poland) Marcin Krawczyński, Gdańsk (Poland) Michał Kuczyński, Wrocław (Poland) Kornelia Kulig, Los Angeles (USA) Lesław Kulmatycki, Wrocław (Poland) Krzysztof Kusy, Poznań (Poland) Radosław Laskowski, Gdańsk (Poland) Maria Laurentowska, Poznań (Poland) Janusz Maciaszek, Poznań (Poland) Robert M. Malina, Texas (USA) Philip E. Martin, Ames (USA) Małgorzata Mraz, Wrocław (Poland) Wiesław Osiński, Poznań (Poland) Jadwiga Pietraszewska, Wrocław (Poland) John M. Popovich, East Lansing (USA) Marek Rejman, Wrocław (Poland) Andrzej Rokita, Wrocław (Poland) Jerzy Sadowski, Biała Podlaska (Poland) Sachithra Samarawickrame, Los Angeles (USA) Krzysztof Sas-Nowosielski, Katowice (Poland) Małgorzata Sekułowicz, Wrocław (Poland) Adam Siemieński, Wrocław (Poland) Teresa Sławińska-Ochla, Wrocław (Poland) Małgorzata Słowińska-Lisowska, Wrocław (Poland) Stanisław Solnik, Wrocław (Poland) Rafał Stemplewski, Wrocław (Poland) Andrzej Suchanowski, Olsztyn (Poland) Robert Szeklicki, Poznań (Poland) Andrzej Szmajke, Opole (Ponad) Rajmund Tomik, Katowice (Poland) Czesław Urbanik, Warszawa (Poland) Dariusz Wieliński, Poznań (Poland) Sławomir Winiarski, Wrocław (Poland) Andrzej Wit, Warszawa (Poland) Michał Wychowański, Warszawa (Poland) Marek Zatoń, Wrocław (Poland) Halina Zdebska, Kraków (Poland) Jacek Zieliński, Poznań (Poland) Stanisław Żak, Kraków (Poland) Ryszard Żarów, Kraków (Poland) Zofia Żukowska, Biała Podlaska (Poland) 284

5 2013, vol. 14 (4), Body satisfaction and time spent on physical activity in Polish students doi: /humo Agnieszka Olchowska-Kotala 1 *, Krystyna Chromik 2 1 Wrocław Medical University, Wroclaw, Poland 2 University School of Physical Education, Wroclaw, Poland Abstract Purpose. The aim of this study was to assess the relationship between body satisfaction, the amount of time spent on physical activity (PA), and body mass index (BMI) in a group of young adults. Methods. A sample of 527 students (351 females and 176 males) aged years were recruited for analysis. Measures of height and weight were collected. Participants completed a questionnaire about PA performed during the previous seven days, intention of increasing PA levels, overall body satisfaction, their ideal BMI, and what parts of their bodies they were most dissatisfied with. Results. Body satisfaction was associated with the amount of time spent on PA in both women and men. No relationship between time spent on PA and BMI was found. In women, lower levels of PA, lower body satisfaction, and a larger discrepancy between actual BMI and ideal BMI was observed when compared with men. The majority of women (85.7%) as well as men (78.4%) intended to increase their PA in the near future. Conclusions. Body satisfaction grows together with increasing the amount of time spent on PA. Young adults are aware of the benefits of PA, but there is a gap between knowledge and practice, highlighting the need for programs that can motivate and educate on how to turn intentions into action. Along with promoting PA, focus on body satisfaction especially among women is also recommended. Key words: physical activity, body satisfaction, BMI, young adults Introduction Physical inactivity has been increasingly recognized as a significant risk factor associated with mortality in adults [1]. Regular and moderate physical activity (PA) has many health benefits and is protective against obesity and other health risks [2]. The literature includes well-documented links between moderate physical activity and mental benefits. As an example, we can mention research conducted on 12,028 randomly selected men and women aged years from Denmark, which showed a decrease in high stress levels with increasing PA [3]. In addition, increased PA was associated with increases in life satisfaction [3 5], happiness [4], and self-esteem [6]. Changes in the social environment have been cited as explanatory factors for decreased PA among young individuals [7]. Young adults in particular, due to the period of transition they experience at this age, often experience numerous lifestyle changes. Yet, it is during this period that young adults develop the PA habits that are maintained in later life. One aspect of interest is how concern about physical appearance can motivate young individuals to engage in PA, since early adulthood is a key risk time for body image problems [8]. It is becoming apparent that many individuals who are even not overweight or obese have some level of body dissatisfaction [9]. Body satisfaction is a multifaceted, * Corresponding author. structural concept that is dependent upon numerous inner biological and psychological components and appears to be a specific domain of global self-esteem [10]. Subjects who reported feeling less attractive and more dissatisfied with their bodies or body weight were found to feature a higher level of psychological problems [11]. Body satisfaction in particular is an important element of self-esteem building for young adults as many are still searching for their life partners and also entering the job market at this stage in life. This population segment is under considerable social and peer pressure to conform to the societal picture of attractiveness and the cultural ideal. One of the factors associated with body satisfaction is the currently adopted concept of body mass index (BMI) [10]. Although obesity is still comparatively uncommon in early adulthood, mean BMI levels in industrialized countries have steadily risen for this population [12]. Data collected from 18,512 university students from 22 countries showed lowest mean BMI among women in Korea (BMI = 19.3) and the highest in the USA (BMI = 22.6). Polish women in this regard were ranked 8 th (BMI = 20.1). For men, lowest mean BMI was observed in Thailand (BMI = 20.5) and the highest in the USA (BMI = 24.3), whereas Polish men were ranked 12 th (BMI = 22.8) [8]. Increased BMI levels were explained in part by the adoption of different lifestyles stemming from environmental changes. Many of the everyday activities of life in the modern world are significantly different from what our bodies have adapted to performing in the course of evolution. Significant changes 285

6 A. Olchowska-Kotala, K. Chromik, Body satisfaction in Polish students in life circumstances, especially those prevalent in urbanized societies, may affect physical activity patterns. Many current occupational requirements in urbanized societies no longer require high physical demands [13], and individuals who become less active negatively impact the functioning of their bodies. Hence, current research should seek to identify new ways of promoting PA. The aim of the study was to assess the relationship between body satisfaction, BMI, and the amount of time spent on PA in a group of students by asking the following research questions: (1) How much time per week do students spend exercising and being physically active, and are they likely to increase PA levels? (2) What parts of body are students least satisfied with? (3) Which of the examined factors (BMI and the amount of time spent on PA) is most closely associated with body satisfaction? Both men and women were included in this study to determine if gender differences exist in body satisfaction and physical activity levels as an attempt to facilitate the creation of gender appropriate prevention strategies and interventions. Material and methods The sample population consisted of 527 randomlyselected students (351 females and 176 males) aged between years attending the University of Environmental and Life Sciences in Wrocław, Poland. The inclusion criterion was for the participant to be a large-city resident for a period of at least one year. The study was conducted in May 2011 during students physical education classes. It began by the participants completing a questionnaire on time spent on physical activity and an assessment of body image and then had their body height and mass measured. Prior to commencement, the study was approved by the local ethics committee and the study procedure was performed in accordance with Declaration of Helsinki. Participation in the study was anonymous and voluntary. Body mass was measured to the nearest 0.1 kg using a model No. 761 medical scale (Seca, USA). Standing height was measured to the nearest 10 mm with a model Posturometer S measuring device (Posmed, Poland), where the subject stood upright in a natural posture with the head in Frankfurt plane. Participants were measured dressed in gym clothes without footwear. BMI was calculated by dividing body mass (kg) by height squared (m 2 ) and grouped into one of four weight categories: underweight (< 18.5 BMI), normal weight ( BMI), overweight ( BMI), and obese (> 30 BMI). On the survey, the amount of time spent on PA was measured by a question asking about the number of hours spent during the past seven days engaged in physical activity (walking, jogging, roller-skating, dancing, team sports, garden work, etc.). Additionally, participants were asked if they were going to increase their PA in the near future. Body satisfaction was measured by three items using a 7-point scale, where participants were asked to rate: (1) how happy they are with their body (from 1 extremely dissatisfied to 7 extremely satisfied); (2) how fit they believe they are (from 1 not at all to 7 extremely fit); (3) how attractive they feel they are to the opposite sex (from 1 not at all to 7 very attractive). Responses to the three items were tallied to create a total body satisfaction indicator. Cronbach s alpha was used as a coefficient of reliability, finding the questions on body satisfaction to be = Furthermore, the respondents were asked to select which part of the body they were most dissatisfied with: legs, stomach, chest, or face. The respondents were also asked to note what body mass and height they would like to have, with these values used to calculate their Ideal BMI. The difference between present mass and ideal mass was calculated by subtracting ideal mass from present mass. Statistical analyses were conducted using SPSS ver. 18 statistical software (IBM, USA). The levels of significance of the differences between the women and men were assessed with Student s t test. Pearson s productmoment correlation was used to examine the associations among study variables by sex. One-way analysis of variance (ANOVA) was performed to examine if there were any differences in PA depending on BMI category (underweight, normal weight, overweight, obese). Statistical significance was set at the p < 0.05 probability level. Results Table 1 provides minimum, maximum, means, and standard deviations for age, mass, height, BMI, and Ideal BMI separately for the male and female student participants. Female respondents (n = 351) had mean BMI of 21.7, with minimum-maximum values ranging from to 41.30, whereas the males respondents (n = 176) had mean BMI of 24.57, ranging from to As shown in Table 1, the tendency to be overweight and obese was larger in men (total 40.9%) compared with women (total overweight and obese women 11.3%). More underweight individuals were observed in women than in men. In women, significantly lower levels of body satisfaction as well as physical activity were observed than in the group of men (Tab. 2). Differences between present BMI and Ideal BMI were compared, finding a higher discrepancy between these two values in women. The majority of women (85.7%) and men (78.4%) confirmed their intention to increase their PA in the near future. Table 3 shows Person s correlation coefficients calculated for sex. No correlation in either women or 286

7 A. Olchowska-Kotala, K. Chromik, Body satisfaction in Polish students Table 1. Characteristics of the participants Min Max SD Women n = 351 Men n = 176 Age Mass Height BMI Ideal BMI BMI (%) underweight 12% normal weight 76.7% overweight 8.5% obesity 2.8% Age Mass Height BMI Ideal BMI BMI (%) underweight 0.6% normal weight 58.5% overweight 34.6% obesity 6.3% Table 2. Differences between the women and men in body satisfaction, the amount of time spent on PA, and the discrepancy between BMI and Ideal BMI Women (n = 351) ± SD Men (n = 176) ± SD t p Time spent on PA (previous seven days) 9.83 ± ± Body satisfaction ± ± Discrepancy between BMI and Ideal BMI 2.51 ± ± Table 3. Correlations between time spent on physical activity, BMI, body satisfaction, discrepancy between BMI and ideal BMI Time spent on PA BMI Body satisfaction Women Time spent on PA BMI 0.03 Body satisfaction 0.19** 0.33** Discrepancy between BMI and Ideal BMI ** 0.32** Men ** p < 0.001; * p < 0.05 Time spent on PA BMI 0.02 Body satisfaction 0.25** 0.12 Discrepancy between BMI and Ideal BMI ** 0.22* men was observed between the amount of PA performed in the preceding week and BMI. However, in both groups a positive correlation between PA and body satisfaction was found. ANOVA on the differences in PA among the BMI categories (underweight, normal weight, overweight, obese) showed a lack of statistically significant differences in women F (3, 346) = 0.147, p = and in men F (3, 172) = 0.010, p = Analysis on what parts of the body the participants were most dissatisfied with found that most men were dissatisfied with their stomach (43.2%), their chest (26.1%), and then legs (18.2%). The most satisfactory part of their bodies was their face, with only 12.5% of 287

8 A. Olchowska-Kotala, K. Chromik, Body satisfaction in Polish students male respondents reporting dissatisfaction. Similar to men, the women were mostly dissatisfied with their stomach (41.1%). The legs were ranked second (35.1%), then the chest (14.3%). The face, just like in men, was ranked last (9.4%). Discussion The aim of this study was to determine if there was any association between body satisfaction and actual body mass and height and the amount of time spent on PA in young adults. In addition, we also examined which parts of the body this group is most dissatisfied with in order to determine on what a campaign aimed at promoting PA among young adults should focus. The young adults in this study had, on average, normal BMI and reported physical activity levels higher than recommended standards (30 min/d of PA on most days [14]). It presumed that the greater amount of time spent on PA by this group was a function of their age. Furthermore, the study was carried out in the spring, which may have influenced the amount of actively spent time. In our study, we found a positive correlation between body satisfaction and the amount of time spent on PA. This correlation was observed in both the female and male students. Similar results were obtained in a study on American students [15]. Therefore, it appears that an increase in the time spent on PA is associated with an increase in the level of body satisfaction, with the opposite also being quite likely. However, causality cannot be assumed from the results as this study used a cross-sectional design. Therefore, body satisfaction may be both a cause and a consequence of PA. However, a systematic review of the correlations found in other longitudinal and experimental studies leads to the conclusion that regular PA results in an increased perceived positive changes in physical appearance, fitness, body mass, and health [16]. Given the above considerations, on the basis of our research it can be assumed that body satisfaction can be improved by increased PA levels. This is particularly important for young adults, who may benefit psychologically from increased PA at this very critical stage in their lives. Men showed higher body satisfaction (based on the three-item questionnaire and by the smaller discrepancy between Ideal BMI and actual BMI). This supports previous findings on gender differences in body satisfaction, which stated that body dissatisfaction was more common among women [17 19]. Women are considered to attach far more importance to their physical appearance, including body mass, than men. The desire to be smaller than one s current size was also found to be more widespread in women than in men [20]. In Western society, thinness has become the idealized standard of feminine beauty. This standard has been personally internalized by many women who feel their body size to be excessive and unacceptable [21]. Our study showed a relationship between body satisfaction and BMI in women but not in men. In previous studies, a similar difference in the relationship between body satisfaction and BMI in women and men was also found. Among female adolescents, a linear increase in poor body satisfaction with increasing BMI was observed by Austin [22]. Among boys, however, this author found a U-shaped association, where low BMI and those with high BMI reported higher levels of poor body satisfaction. In another study conducted on college students, only underweight (BMI < 20) women and men were similarly satisfied with their body mass and shape. With an increase of BMI, however, young women became disproportionately more dissatisfied, and both normal weight and overweight women expressed greater dissatisfaction than their male peers [23]. Our study confirmed that body satisfaction in women is associated with their actual size. However, this study s sample presented too few underweight and overweight individuals to more precisely define the shape of this relationship. The part of body associated with the highest levels of dissatisfaction in women as well as in men was the stomach. This indicates the direction campaigns should take to improve PA levels in this population, providing emphasis on the positive influence of exercise on this part of body to encourage the participation in PA. These results are in fair agreement with previous studies, although they indicated that the chest muscles are the most important for men [24]. In our study, one in four male respondents were dissatisfied with his chest. At the same time, almost one in three women were dissatisfied with her legs. Therefore, promotional slogans that also advertise the influence of PA on the growth of chest muscle tissue and the toning of leg muscle are suggested. In the present study, no association between BMI and the amount of time spent on PA was found. The literature is inconsistent on the correlation between BMI and PA. Most data support the thesis that people with higher levels of PA usually have lower indexes of BMI [25]. However, not all studies found this relationship. In the research conducted by Dowda [26] on 4,152 young adults, BMI was negatively correlated with PA in women but not in men. Nonetheless, Seo [27] examined 4,685 college students finding BMI was not associated with a lack of regular PA from all four of the analyzed countries (USA, Costa Rica, India, South Korea). However, the fact that no correlation between BMI and PA was found in our or in Seo s research might result from the specific character of the study population (students, few of whom are relatively overweight). As was found by other researchers [7, 27, 28], men had higher rates of participation in PA than did women. It is worth considering that the vast majority of young women and men intended to increase the amount of 288

9 A. Olchowska-Kotala, K. Chromik, Body satisfaction in Polish students PA in the near future. However, it is very unlikely that all respondents who declared their intention of increasing PA will actually fulfill their promise. This finding shows that although young adults are aware of the benefits of PA, there is a gap between knowledge and practice. A lack of a strong correlation between intention and the motivation to fulfill their promise to engage in more PA was found in many studies and termed as the intentionbehavior gap by psychologists [29]. An implementation intentions intervention is felt to be one of the best ways to minimize this gap, where an individual prepares a schedule, including information about the time, place, and way they will perform an action. It was proven that interventions based on implementation intention might initiate regular PA and increase the probability that individuals maintain the required activity level for a longer period of time [30]. Conducting such interventions seems to be advisable considering our results showing the mutual intentions of increasing PA among both the male and female respondents. The study has some limitations. Firstly, the sample consisted of few overweight individuals. This may be the result of this population having a relatively low obesity rate. Furthermore, our respondents were university students, where studies conducted in Poland [31] as well as in other countries [32] found an inverse relationship between educational level and BMI. Therefore, the specific character of this population may be the cause for the relatively high recorded levels of PA, as both educational level [26] and living in urban areas [33] are connected with active lifestyle. Secondly, participation in physical activity was measured by only one self-reported question. On the basis of our tool, we were able to only establish the average time of various daily PA but not if it was of moderate-intensity or vigorous- intensity. Future research should incorporate more precise measures of PA or incorporate an objective measure of physical activity by using pedometers and accelero meters to further explore the relationship between physical activity, BMI, and body satisfaction. Finally, as the collected data was correlational in nature, it could not therefore address causality. Conclusions Despite its limitations, there are still a number of strengths of the study that should be taken into consideration. Firstly, this study showed a significant association between the amount of time spent actively and body satisfaction. Body satisfaction is one of the factors that form general well-being and participation in PA may be influential in improving mental well-being in young adults. Well-being should be a key argument in future campaigns for increasing PA. Secondly, both young men and women were similarly dissatisfied with similar parts of their bodies. This can allow PA promotional campaigns to better target their audience by knowing what physical aspects they can focus on. Thirdly, our findings showed that the majority of the sample intended to increase the amount of physical activity they perform. We suggest using implementation intentions programs (such as being conducted during PE classes) designed to further motivate this population segment by turning intentions into action. Although our study was aimed primarily at finding arguments for the promotion of increased PA among young adults, the findings also suggest that additional promotional campaigns on increasing body satisfaction, especially among women, would also be recommended. References 1. Mokdad A.H., Marks J.S., Stroup D.F., Gerberding J.L., Actual causes of death in the United States. 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10 A. Olchowska-Kotala, K. Chromik, Body satisfaction in Polish students population. J Obes Relat Metab Disord, 2000, 24 (7), Kyröläinen H., Santtila M., Nindl B.C., Vasankari T., Physical fitness profiles of young men. Sports Med, 2010, 40 (11), , doi: / Haskell W.L., Lee I.M., Pate R.R., Powell K.E., Blair S.N., Franklin B.A. et al., Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Circulation, 2007, 116 (9), , doi: CIRCULATIONAHA Zabinski M.F., Calfas K.J., Gehrman C.A., Wilfley D.E., Sallis J.F., Effects of a physical activity intervention on body image in university seniors: Project GRAD. Ann Behav Med, 2001, 23 (4), , doi: /S ABM 2304_ Fox K.R., The influence of physical activity on mental well-being. Public Health Nutr, 1999, 2 (Suppl. 3a), , doi: /S Ogden J., Mundray K., The effect of the media on body satisfaction: the role of gender and size. Eur Eat Disord Rev, 1996, 4 (3), , doi: /(SICI) (199609) 4:3<171::AID-ERV132>3.0.CO;2-U. 18. Olmsted M.P., McFarlane T., Body weight and body image. BMC Women s Health, 2004, 4 (Suppl. 1), S5, doi: / S1-S Kenedy M.A., Templeton L., Gandi A., Gorzalka B.B., Asian body image satisfaction: ethnic and gender differences across Chinese, Indio-Asian, and European-descent students. Eat Disord J Treat Prev, 2004, 12 (4), , doi: / Monteath S.A., McCabe M.P., The influence of societal factors on female body image. J Soc Psychol, 1997, 137 (6), , doi: / Cash T.F., Green G.K., Body weight and body image among college women: perception, cognition, and affect. J Pers Assess, 1986, 50 (2), , doi: /s jpa 5002_ Austin S.B., Haines J., Veugelers P.J., Body satisfaction and body weight: gender differences and sociodemographic determinants. BMC Public Health, 2009, 9, , doi: / Pingitore R., Spring B., Garfield D., Gender differences in body satisfaction. Obes Res, 1997, 5 (5), , doi: /j tb00662.x. 24. Raevuori A., Keski-Rahkonen A., Bulik C.M., Rose R.J., Rissanen A., Kaprio J., Muscle dissatisfaction in young men. Clin Pract Epidemiol Ment Health, 2006, 2 (6), 1 8, doi: / Spees C.K., Scott J.M., Taylor C.A., Differences in amounts and types of physical activity by obesity status in US adults. Am J Health Behav, 2012, 36 (1), 56 65, doi: /AJHB Dowda M., Ainsworth B.E., Addy C.L., Saunders R., Riner W., Correlates of physical activity among U.S. young adults, 18 to30 years of age, from NHANES III. Ann Behav Med, 2003, 26 (1), 15 23, doi: / S ABM2601_ Seo D.C., Torabi M.R., Jiang N., Fernandez-Rojas X., Park B.H., Cross-cultural comparison of lack of regular physical activity among college students: Universal versus transversal. Int J Behav Med, 2009, 16 (4), , doi: /s x. 28. Behrens L.K, Dinger M.K., Motion sensor reactivity in physically active young adults. Res Q Exerc Sport, 2007, 78 (2), Luszczynska A., Schwarzer R., Lippke S., Mazurkiewicz M., Self-efficacy as a moderator of the planning-behaviour relationship in interventions designed to promote physical activity. Psychol Health, 2011, 26 (2), , doi: / Luszczynska A., An implementation intentions intervention, the use of a planning strategy, and physical activity after myocardial infarction. Soc Sci Med, 2006, 62 (4), , doi: /j.socscimed Zatońska K., Janik-Koncewicz K., Regulska-Ilow B., Ilow R., Różańska D., Szuba A. et al., Prevalence of obesity baseline assessment in the prospective cohort PONS study. Ann Agric Environ Med, 2011, 18 (2), Molarius A., Seidell J.C., Sans S., Tuomilehto J., Kuulasmaa K., Educational level, relative body weight, and changes in their association over 10 years: an international perspective from the WHO MONICA project. Am J Public Health, 2000, 90 (8), Hoffmann K., Bryl W., Marcinkowski J.T., Strażyńska A., Pupek-Musialik D., Estimation of physical activity and prevalence of excessive body mass in rural and urban Polish adolescents. Ann Agric Environ Med 2011, 18 (2), Paper received by the Editors: September 20, 2013 Paper accepted for publication: November 12, 2013 Correspondence address Agnieszka Olchowska-Kotala Zakład Humanistycznych Nauk Lekarskich Uniwersytet Medyczny we Wrocławiu ul. Mikulicza-Radeckiego Wrocław, Poland agnieszkakotala1@gazeta.pl 290

11 2013, vol. 14 (4), Changes in body composition and physical fitness of 7-year-old girls after completing a 12-month artistic gymnastics training program doi: /humo Tomasz Boraczyński 1 *, Michał Boraczyński 1, Sandra Boraczyńska 1, Anna Michels 2 1 Józef Rusiecki University, Olsztyn, Poland 2 M.G. Bublewicz No. 5 Sports Champion School, Olsztyn, Poland Abstract Purpose. The aim of the study was to evaluate changes in body composition and physical fitness in girls aged 7 years before and after a 12-month macrocycle artistic gymnastics training program. Methods. The study involved 32 girls attending the first grade at a sports-focused primary school with a specialization in artistic gymnastics. The study was conducted at the beginning and after an annual training cycle. Measures of body height, body mass, and body composition were performed. Physical fitness was assessed using the Eurofit physical fitness test battery. Results. The results showed average body composition and a high initial level and later dynamic increase in the physical fitness of the participants. Conclusions. The dynamic increase in the results of six Eurofit tests and the overall high level of results in seven of the tests after completing the annual training cycle is evidence of the high effectiveness of the applied training program in improving the physical fitness of the tested girls. The reasons for the lack of significant progress in one of the tests measuring agility (10 5 m shuttle run) are unclear, requiring more in-depth analysis of the training process used by trainers with focus on the applied methods, means, and training load volumes. The Eurofit test battery proved to be a precise tool to assess changes in the physical fitness of the tested girls after completing the annual training cycle and is therefore worth recommending at early training stage in gymnastics. The results provide useful information in optimizing the training loads of artistic gymnasts at the initial training stage. Key words: girls aged 7 8 years, artistic gymnastics, body composition, physical fitness, Eurofit Introduction Contemporarily, it is believed that in order to achieve a high degree of complex motor performance in many sports disciplines training needs to begin in early childhood. This is in part the result of modern competitive sport being characterized by an ever-continuing increase in performance levels [1, 2]. This development is the result of growing knowledge on the human body s adaptation to exercise, improved athlete recruitment and selection methods, and more efficient training exercises and programs [2 4]. The particular importance of the training process at its initial stage is due to the role it plays in the development of athletic motor skills. Nonetheless, a high level of wide-ranging physical fitness provides a foundation on which specific motor abilities and skills can later be developed. The basis for assessing the training process in sports involves a systematic examination of training effects. Such an evaluation requires the use of objective, quantitative, and qualitative criteria for assessing motor skill level, the body s response to training loads, the characteristics of pertinent mental processes, and the level of athletic technical and tactical preparation. All of these factors are then interpreted so as to optimize * Corresponding author. the training process. However, this optimization process requires coaches and educators to continually monitor the training effects for each athlete to allow for the individualization of training loads [1 8]. The above-mentioned factors combine to form an optimal fitness structure, which is particularly important in sports such as artistic gymnastics where a great deal of significance is attributed to motor abilities and particularly coordination [1, 5]. Artistic gymnastics, due to its physical structure, athletic demands, and physiological profile, belongs to a group of coordinative difficult aesthetic and technical disciplines whose energy demands are met mainly by the anaerobic glycolytic system. Potop et al. [10] highlighted the importance of using specific training loads to elicit peak improvements in women s artistic gymnastics by highlighting the importance of an optimum relationship between workload and technical-physical training level. Increased performance requires the combination of an athlete s individual fitness levels and coordination skills to be in mutual harmony with suitable training techniques and workouts at different difficulties [11, 12]. It needs to be stressed that the effectiveness of the training process in gymnastics depends on the individual abilities of athletes and what useful indicators on performance can be gained across training stages. This also relates to the importance that is attributed to the recruitment/ selection stage, as it aims to identify talented individuals and determine their developmental potential [1, 4]. 291

12 T. Boraczyński, M. Boraczyński, S. Boraczyńska, A. Michels, Training effects in young female gymnasts Many experts have emphasized the crucial importance of possessing a broad level of physical fitness in the athletic development of artistic gymnastics [1, 5, 8, 11 16]. For these reasons, the aim of the present study was to evaluate the anthropometric characteristics, body composition, and selected components of physical fitness of 7 year-old girls beginning an introductory level of gymnastics and after the completion of a full (12-month) training macrocycle. Material and methods A quasi-experimental, longitudinal (pre- and posttest) design was adopted to examine the effects of gymnastics training on the individual components of body composition and physical fitness in 32 pre-pubertal girls (mean chronological age 7.72 ± 0.30 years) attending the first grade at the No. 23 Primary School of Sports Championship in Olsztyn, Poland. The girls were attending the school with a specialization in artistic gymnastics and were admitted based on a set of performance tests. The subjects participated in one daily training unit (4 h) six days every week in a specialized gym. Each training unit contained two training phases: routine development (RD) and strength-technical conditioning (STC). Each of phases lasted 2 h. The RD phase started with a 30-min warm-up which included 8 to 10 min of slow running and a 20-min set of athletic exercises (skipping, hand walking, etc.). One and a half hours was devoted to choreographic-ballet elements and active stretching of the upper and lower limb muscle groups. The STC phase consisted of general and technical-strength development performed on gymnastic apparatuses such as the high bar, parallel bars, etc. Training impact (loads) were primarily administered on four gymnastics apparatuses (30 min on each): (1) gymnastics table vaulting; (2) parallel bars standing, turnovers, turnstiles, drop jumps; (3) balance beam choreographic elements, ballet jumps; and (4) free exercises acrobatics, handsprings on one and two lower limbs, forward and backward somersaults, etc. Examples of the duration of specific exercises per standard training unit were, for example, an average of min of static support loading on the hands/ wrists or an average of 3.5 min swinging on the bars. Heart rate was monitored during chosen training units. It was estimated that about 63% of total training time was devoted to rest or recovery. Mean heart rate was 139 beats per minute (bpm) although varied depending on apparatus and training phase and approached 60% to 65% of participants maximum heart rate. Testing was conducted twice at the Central Research Laboratory of the Joseph Rusiecki Olsztyn University in the morning (08:00 11:00). Baseline tests (pre-test) were completed at the beginning of the participants training program and a post-test was administered after 12 months of them regularly training. The period between pre- and post-tests constituted a complete annual macrocycle. Participants had to attend at least 90% of the training units to be included in data analysis and attend both pre- and post-tests. Prior to testing parental consent and child assent were obtained, and the study received the approval of the local ethics committee. Participants body height was measured with a calibrated WB-150 medical weight/stadiometer (ZPU Tryb- Wag, Poland) with an accuracy of 0.1 cm. Body mass (with an accuracy of 0.1 kg) and body fat content (with an accuracy of 0.1%) were measured using a BC 418 MA electronic body composition analyzer (Tanita, Japan) using bioelectric impedance analysis (BIA). During measurement participants were barefoot wearing underwear only. All anthropometric measurements were performed by the same certified investigator and in accordance with international standard procedures. Physical fitness was determined by administering eight tests included in the Eurofit physical fitness battery [17]. Due to the research task, an assessment of cardio-respiratory endurance was not performed. As gymnasts regularly train barefoot, the flamingo balance test (FLB) was performed without footwear. To allow for a more detailed interpretation of participants physical fitness, an additional variable was introduced relative hand strength (HGR) in relation to body mass (N/kg). Body height and mass, body mass index, and the results of the Eurofit tests were evaluated by percentile ranks and point scores according to national norm score tables and percentile charts [18, 19]. Following data collection, descriptive statistics (means and standard deviations) were calculated. Minimal and maximal values and the coefficient of variation (CV) for each variable were presented. The significance of differences between the results of measurements carried out at pre- and post-test was assessed using Student s t test for dependent samples (paired t tests). Tables show the t values and the p values. The alpha-level for significance was set to Statistical analysis was performed using the StatisticaPL v. 10 software package (StatSoft, USA). Results Table 1 shows the results of the basic anthropometric characteristics of tested gymnasts in both trials (preand post-), the significance of differences between the variables, and biological (physical) development based on norms for the age-specific general population (scaled scores and percentile ranks) [18, 19]. The participants were below the norms for body height and mass at pre- and post-test in comparison with the general population of Polish girls in this age group [18], scoring points in the percentiles, respectively. Nonetheless, there was a significant increase (p = ) in body height and mass after the one-year period as the obvious result of biological development. It should be noted that an increase in body 292

13 T. Boraczyński, M. Boraczyński, S. Boraczyńska, Anna Michels, Training effects in young female gymnasts Table 1. Basic anthropometric characteristics of the artistic gymnasts (N = 32) Variables Age (years) BM (kg) BH (cm) BF (%) FM (kg) FFM (kg) FM/FFM (%) BMI (kg/m²) M (SD) 7.23 (0.28) (2.76) (3.78) (3.51) 4.25 (1.18) (1.96) (5.25) (1.28) Min-Max CV c./pts. 38.2/ / /47 Pre-test M (SD) 8.21 (0.31) (2.94) (4.10) (2.51) 4.95 (0.99) (2.26) (3.86) (1.20) Min-Max CV c./pts. 34.5/ / /46 Post-test Difference (%) t p BM body mass, BH body height, BF body fat, FM fat mass, FFM fat-free mass, FM/FFM ratio of fat mass and fat free mass, BMI body mass index, M mean value, SD standard deviation, Min minimal value, Max maximal value, CV coefficient of variation, c. percentile, pts. points, t t value in Student s t test, p value based on the Student s t test Table 2. Results of the Eurofit physical fitness tests of the artistic gymnasts (N = 32) Variables FLB (n) PLT (s) SAR (cm) SBJ (cm) HGR (N) HGR (N/kg) SUP (n) BAH (s) SHR (s) M (SD) (6.33) (2.62) 9.69 (4.91) (11.2) (20.4) 4.51 (0.69) (4.71) (9.01) (2.17) Min Max CV c./pts. 6.7/ / / / / / / /56 Pre-test M (SD) (4.35) (1.88) (4.37) (9.7) (21.9) 5.06 (0.61) (3.72) (17.53) (2.33) Min Max CV c./pts. 18.4/ / / / / / / /53 Post-test Difference (%) t p FLB flamingo balance test, PLT plate tapping, SAR sit-and-reach test, SBJ standing broad jump, HGR hand grip test, SUP Sit-ups, BAH bent arm hang, SHR 10 5 m shuttle run, M mean value, SD standard deviation, Min minimal value, Max maximal value, CV coefficient of variation, c. percentile, pts. points, t t value in Student s t test; p value based on the Student s t test; values in italics denote estimated percentile ranks and point scores 293

14 T. Boraczyński, M. Boraczyński, S. Boraczyńska, A. Michels, Training effects in young female gymnasts mass can negatively influence performance in aesthetic sports and in those which a high power to body mass ratio is important. Body mass index (BMI) in both trials was also below the general population norms of Polish girls (47 46 pts. and c., respectively). Body fat percentage (BF) was at the same level in both trials. However, due to natural biological growth and increases in body size (body height and mass), fat mass (FM) increased significantly (p = ). It should be noted that the size of the coefficient of variation (CV) of the percentage of body fat (BF) and fat mass (FM) strongly decreased in the post-test. This reflects a decrease of inter-individual diversity in the tested group. Fat-free mass increased since fat mass and body mass either remained constant or decreased. The ratio of fat mass to fat-free mass (FM/FFM) is important for physical fitness especially in exercises where the whole body is rapidly lifted (running, jumping). As there are elements of running, jumping, or lifting the body in each gymnastics exercise on different apparatuses, the importance of the FM/FFM ratio is significant. In the present study, this ratio did not change significantly in the group during the observed period (p = ). Table 2 shows the participants results in the eight Eurofit tests [16], which were evaluated with respect to national norms [see 19 for a reference sample] based on research conducted in the 2009/2010 school year on a representative group of Polish girls (N = 23704) from all regions of Poland. The results of the six physical tests performed at baseline (pre-test) were at a high and very high level (ranging from c. and pts.) according to the score tables. This indicates the high level of physical fitness of the tested participants at the beginning of their training. The percentile and point scores in seven of the Eurofit tests (PLT, SAR, SBJ, HGR, SUP, BAH, SHR) were summed in order to assess the impact of the annual training cycle on the results of applied tests. Subsequently, the mean values were calculated and amounted to c. and pts. at baseline (pre-test) and c. and pts. at post-test, improving by 7.18% and 8.51%, respectively. The static balance test results (flamingo balance test FLB) could not be directly estimated from the percentile charts and point tables due to the used methodology to modify performance. This test was performed without footwear, which undoubtedly made it more difficult to maintain balance and therefore allowed for greater differentiation of the results. However, the participants significantly improved in this test (36.77%, p = ). An ad hoc assessment on the basis of the score tables showed they increased from 6.7 c. and 36 pts. to 18.4 c. and 41 pts. The results of the test measuring the speed of upper limb movement (plate tapping test PLT) were already at a high level at baseline based on the score tables (72.6 c. and 56 pts.) and significantly improved (14.83%, p = ) at post-test (86.4 c. and 61 pts.). The results of the test measuring flexibility of the sciatic-tibial muscles and lower back (sit-and-reach test SAR) were at a very high level at baseline (84.1 c. and 60 pts.). The participants results improved after the 12-month gymnastics training program by 43.55% (p = ), obtaining 95.5 c. and 67 pts. At the same time, the differences between the results of the individual participants, as evidenced by significantly lower coefficients of variation (50.67% at pre-test and 31.44% at post-test), decreased significantly. The test results of lower limb explosive power (standing broad jump SBJ) improved relatively little (7.74%), but the increase was statistically significant (p = ). An evaluation of the results based on the score tables showed the same scores in both trials (86.4 c. and 61 pts.), suggesting no effects of training. The results of the hand grip test (HGR) showed a significant increase after 12 months of gymnastics training (24.11%, p = ). Additionally, the relative strength of the hand to body mass increased significantly during the observation period although the increase was relatively lower (12.10%, p = ). An evaluation of the results based on the percentile charts showed this motor skill was performed with greater success (from 57.9 to 65.5 c.). A very high level of performance at baseline (90.3 c. and 62 pts.) was found in the test measuring abdominal muscular and hip flexor endurance (sit-ups test SUP) and a significant improvement was noted at post-test (28.48%, p = ). An evaluation of the results based on the score tables also showed substantial progress (98.6 c and 72 pts.). Very high performance (90.3 c. and 63 pts.) was observed in the test of arm and shoulder muscular endurance (bent-arm hang test BAH), showing the highest (of all tests) progress at post-test (146.28%; p = ). An evaluation of the test results based on the score tables also showed very high results (99.8 c. and 79 pts.). Out of all the Eurofit tests, this test also showed the largest variability between the participants and the relatively largest range of decrease in these differences post-test as evidenced by the size of the coefficient of variation (65.31% at pre-test and 51.31% at post-test). There were no statistically significant improvements after 12 months of gymnastic training only in the speedagility test (10 5 m shuttle run SHR). An evaluation of the test results showed a decline from 72.6 c. and 56 pts. to 61.8 c. and 53 pts. based on the score tables. Overall, the level of physical fitness of the participants improved significantly in seven of the Eurofit motor fitness tests. Discussion Significant increases in physical fitness and the comprehensive and the harmonious development of the body constitute some of the key objectives in gymnastics 294

15 T. Boraczyński, M. Boraczyński, S. Boraczyńska, Anna Michels, Training effects in young female gymnasts and are closely linked to the development of motor abilities (strength, speed, endurance, agility, flexibility, coordination and others) [20, 21]. The specialized literature emphasizes the importance of somatic build and body composition in gymnastics [1, 5, 12, 14]. Di Cagno et al. [12] pointed out the significant influence of somatic build, body tissue composition, and jumping abilities on results in gymnastics and recommended using measurements of these factors to identify the predispositions of children during the selection process. A study conducted by Fjørtoft [22] that included 75 children in Norway (37 girls) aged 5 7 years showed a strong correlation between the results of the Eurofit test battery and age. However, this author found that basic somatic parameters (body height and mass) had no significant effect on individual physical fitness variables in this studied age group. In the present study, lower values of the girls body height and mass were recorded than what is considered to be the population norm for Polish girls [18]. Body height and mass were located at the 38 th percentile at baseline (pre-test), suggesting that mostly short and slim girls were selected. Coaches confirmed that taller and heavier girls have more difficulties in performing technically difficult exercises. According to Malina et al. [23], gymnasts as a group demonstrated patterns of growth and maturation similar to those observed among early-, normal-, and late-maturing individuals who were not athletes. Given the significant impact of biological age on body size and physical fitness, this suggests the need to identify the biological age of girls at the recruiting and selection process in gymnastics. This can facilitate the identification of athletes with the most beneficial features and somatic build proportions as well as provide an objective assessment of physical fitness. Specialists dealing with the issues surrounding gymnastics training emphasize that sports results at the highest level require comprehensive physical and mental preparation [1, 5, 8, 11, 14, 16, 21, 24 26]. Sawczyn [25] underlined the importance of physical fitness in gymnastics, showing systematically increasing differences over time between gymnasts and non-trained subjects aged years in flexibility, speed, strength, agility and endurance tests. However, some researchers [27, 28] have stated that it is not currently possible to establish a cause-effect relationship between training and performance in gymnastics due to limitations in the available data, inadequate descriptions of the training processes, failure to consider other factors affecting growth and maturation, and failure to address epidemiological causation criteria. Attempts to isolate the effects of gymnastics training on physical fitness took into account covariates such as age, body size, and physical maturity. Kochanowicz [5] proposed a complex set of indicators to assess motor preparation at the initial stage of training in gymnasts aged 6 7 years. These included an evaluation of balance function, agility, and special technical skills. The basis for selecting these indicators was the results of earlier studies on the physical fitness of gymnasts by the author [14, 15]. The findings discussed above suggest the importance of systematically monitoring comprehensive, targeted, and specific indicators of physical fitness during the gymnastics training process. Currently different motor tests are used to assess physical fitness at the initial stage of training. One of the most developed and recommended by the Council of Europe is the Eurofit physical fitness test battery [17]. Mahoney and Boreham [29] found the Eurofit test battery to be accurate and reliable in the assessment of comprehensive physical fitness in school children. The Eurofit test battery has been previously applied in the analysis of the biological and motor development of children and youth in Poland. A nationwide reference in the form of percentiles charts was developed in a 1999 study conducted on a population of more than children and adolescents (including more than girls) attending various schools in Poland [30]. Additional studies were performed in the school year to update national norms by analyzing a population of youths (including girls) [31]. Research was also undertaken to determine the relationship between physical fitness levels estimated by the Eurofit test battery and health levels in 615 adolescents aged years [32]. The use of the Eurofit test battery to study the effects of training on physical performance has also been undertaken in many scientific studies. Baquet et al. [33] conducted an experiment to evaluate the effects of a 7-week interval training program on the physical fitness of children (girls and boys aged 8 11 years). The experiment showed that high-intensity speed interval training influenced a significant improvement in explosive strength (standing broad jump) and agility (10 5 m shuttle run). It is also known that physical fitness improves with age during childhood and adolescence, although this development may not be equal for all motor skills [34]. This fact was confirmed by the test results of the examined gymnasts in the present study. Taking into account the findings of the above-cited works, the high and very high levels of performance in the six Eurofit tests at the beginning of training program confirm the accurate selection of the girls to the gymnastics program. However, the physical fitness test results in the group of gymnasts were highly varied, from a 0.38% decrease in the agility test (SHR) to a % increase in the test of muscular endurance of upper limbs and shoulder girdle (BAH). Nonetheless, a considerable statistically significant improvement (p < ) was recorded in seven out of the eight administered motor tests. In addition, evaluation of the results of six tests after the participants had completed the 12-month training program found significant increases in the percentile ranks and point scores based on the national norms charts and scales. The large increases 295

16 T. Boraczyński, M. Boraczyński, S. Boraczyńska, A. Michels, Training effects in young female gymnasts in the results of six tests as well as the very high level of performance point to the high effectiveness of the adopted training program in comprehensively shaping the physical fitness levels of the tested participants. The largest improvement (146.3%) was observed in the test of muscular endurance of the upper limbs and shoulder girdle (BAH) out of all the eight tests. Significant improvements (28.48%) were also seen in the test of abdominal muscular and hip flexors endurance (SUP). The results of both of these tests are determined to a large extent by muscular endurance, a core focus in gymnastics training. The second largest improvement among the tested group was noted in the test measuring flexibility of the sciatic-tibial muscles and lower back (SAR). The participants scored very high at baseline (84.1 c. and 60 pts.) and after 12 months of gymnastics training they performed exceptionally well (pre-test: 95.5 c. and 67 pts.). Such dynamic progress in this test was undoubtedly the result of training aimed at increasing joint mobility and skeletal muscle length due to its particular importance in the effective performance of gymnastic exercises. This improvement is even more impressive when considering the results of Malina et al. [35], who found that girls aged 5 and 11 years show relatively stable results in the Eurofit s flexibility test (SAR) and only after 14 years of age does performance increase. The speed and frequency of movements is known to develop the most intensively between 7 and 12 years of age [35]. The processes in charge of maintaining optimal body position mature around 6 years of age and the ability to maintain body balance improves together with age [35]. The results of physical fitness tests in the present study confirm these observations. A significant improvement was observed in the static balance test (FLB), which probably was the result of intense proprioceptive training and vestibular stimulation. These in concert resulted in the rapid improvement of the balance system s functioning. In studies on young elite gymnasts in three age groups (9 10, 11 12, and years), increasing age and competitive level was correlated with improved motor abilities both in regards to fitness level and coordination ability [1, 25, 36]. Particularly high levels were demonstrated in such abilities as: overall coordination, static and dynamic balance, kinesthetic skills differentiating movement, endurance, eye-hand coordination, and simple and complex reaction times. The results presented in the present study are consistent with the cited authors. The tested gymnasts featured large improvements in the static balance test (FLB), which was previously mentioned to be most likely due to a strong stimulation of various systems (proprioception and vestibular systems) that constitute the balance system. One of the most puzzling issues in the present study was the lack of significant progress in the agility test (10 5 m shuttle run SHR). According to Malina et al. [35] the results of the standing broad jump (SBJ), shuttle run (SHR), and bent arm hang (BAH) increase linearly with age in both sexes until they reach adolescence. The reasons for the lack of substantial progress in the shuttle run are unclear considering the gymnastics training the participants performed every day with a large proportion of the exercises aimed at shaping agility. This points to the need for more in-depth analysis of the training process used by trainers with focus on the applied methods, means, and training load volumes. The findings of the authors presented above show the importance of establishing the level of physical fitness preparation both at the recruitment and selection stages as well as throughout the training process. At the same time, researchers have pointed out that only certain psychophysical and functional features are modified, and to a relatively small extent, during long-term training [1, 15, 37]. Hence, these findings underline the need to seek candidates with high predispositions in those motor skills essential in gymnastics at the recruitment and selection stages. Zaporozhanov et al. [16] investigated the gymnastic predispositions of seven girls aged 7.7 years and eleven girls aged 9.3 years. Based on the size of the differences in each of the skills assessed by the Eurofit test battery, they distinguished four tests as the most accurate and reliable indicators of gymnastic predisposition: the speed of the upper limb movement (PLT), jumping ability (SBJ), agility (SHR), and relative hand strength (HGR). The authors stated that the results of these four tests differentiated the groups of gymnasts to the smallest extent and, in their opinion, provided evidence of the strong determination of genetic abilities that influence the results in the selected tests. The authors postulated that research be performed throughout the training process, as it could identify the improvement dynamics of individual motor abilities and the impact of these abilities on gymnasts performance level. These four tests were also distinguished in another study on twelve gymnasts aged 6.9 years and twelve aged 10.0 years. [11]. In a similar vein, Hutchison et al. stressed the importance of continually monitoring jumping abilities in elite gymnastics training [13]. The results of the present study are in line with the findings reported previously. The smallest increases among the Eurofit tests after a year s worth of gymnastics training were observed in the tests measuring agility (SHR), jumping ability (SBJ), relative hand strength (HGR), and the speed of upper limb movement (PLT). This demonstrates the strong genetic determination of the abilities that determine the results of these tests. Simultaneously, this points to the usefulness of these tests in diagnosing the predispositions of girls at the selection stage in artistic gymnastics. In light of the above-discussed findings and the results presented in this study, it appears that the Eurofit battery of tests provides reliable and useful data in as- 296

17 T. Boraczyński, M. Boraczyński, S. Boraczyńska, Anna Michels, Training effects in young female gymnasts sessing the physical fitness levels of children and adolescents involved in physical education and sport [38]. Additionally, the results obtained in the present study may provide useful information in optimizing the training loads of artistic gymnasts at the initial training stage. Conclusions In light of the significant influence of biological age on body size and physical fitness, it is suggested to determine the biological age of girl at the recruitment and selection stage in artistic gymnastics. This may facilitate the identification of athletes with the most advantageous somatic features and proportions and allow for an objective assessment of physical fitness. The high level of results obtained by participants in six Eurofit physical fitness tests at baseline (pre-test) is testament to the accuracy of the selection process applied in participants school. The dynamic increase in the results of six Eurofit physical fitness tests and the concurrent increase in the percentile ranks based on national norms after completing the annual training cycle is evidence of the high effectiveness of the applied training program in improving the physical fitness of the tested girls. The reasons for the lack of significant progress in the agility test (10 5 m shuttle run) are unclear. This points to the need for more in-depth analysis of the training process used by trainers with focus on the applied methods, means, and training load volumes. The Eurofit test battery proved to be a precise tool to assess changes in the physical fitness of the tested girls after completing the annual training cycle and is therefore worth recommending at early training stage in gymnastics. The results obtained in the present study provide useful information in optimizing the training loads of artistic gymnasts at the initial training stage. References 1. Sawczyn S., Training loads in artistic gymnastics for many years of preparation system [in Polish]. AWFiS, Gdańsk Sozański H. (ed.), The basis of theory of sports training [in Polish]. Biblioteka trenera, COS, Warszawa Płatonow W.N., Zaporożanow W.A., Theoretical aspects of selection in the modern sport. Selection, monitoring and predicting in sports training [in Russian]. KGIFK, Kijew 1990, Zaporozanow W.A., Sozański H., Selection and qualification for sport [in Polish]. COS, RCMSKFiS, Warszawa 1997, Kochanowicz K., The basics of controlling the process of sports training in artistic gymnastics [in Polish]. AWFiS, Gdańsk 2006, Kochanowicz K., Zaporożanow W., Modeling as a basis for individualization of sports training in the artistic gymnastics [in Polish]. AWFiS, Gdańsk 2002, Sozański H., Zaporożanow W., Control as an optimization factor in sports training [in Polish]. RCMSKFiS, Warszawa Zaporozhanov V.A., Boraczyński T., Empirical reliability of diagnostic and prognostic estimation of physical standards in children, going in for sports. Pedagog psihol medbiol probl fiz vihov Sportu, 2012, 11, Tibenská M.J., Kyselovicová O., Medeková H., Anthropometric and functional changes and their relationship after two-year aerobic gymnastics training. Acta Fac Pharm Univ Comenianae, 2010, LVII, Potop V., Cîmpeanu M., Urichianu S.T., Timnea O., Influence of specific means on the dynamics of athletic shape in women s artistic gymnastics a case study [in Romanian]. Palestrica Mileniului III Civilizaţie şi Sport, 2011, 12 (4), Boraczyński T., Zaporozhanov V.A., Evaluation criteria of the individual motor predispositions of female artistic gymnasts [in Russian]. Pedagog psihol med-biol probl fiz vihov Sportu, 2010, 10, Di Cagno A., Baldari C., Battaglia C., Brasili P., Merni F., Piazza M et al., Leaping ability and body composition in rhythmic gymnasics for talent identification. J Sports med Phys Fitness, 2008, 48 (3), Hutchinson M.R., Tremain L., Christiansen J., Beitzel J., Improving leaping ability in elite rhythmic gymnasts. Med Sci Sports Exerc, 1998, 30 (10), Kochanowicz K., Comprehensive control in artistic gymnastics [in Polish]. AWF, Gdańsk Kochanowicz K., The specificity of the comprehensive control at the stage of initial training in artistic gymnastics. In: Sozański H., Perkowski K., Śledziewski D. (eds.), Sports training at the turn of the century. The contemporary Olympic sport and sport for all [in Polish]. AWF, Warszawa 2002, Zaporozhanov V., Boraczynski T., Boraczyńska L.B., Giovanis V., Evaluation of predispositions to artistic gymnastics among girls aged 7 10 based on regression equation of selected physical fitness parameters. In: Urniaż J. (ed.), Contemporary trends in physical education and sport [in Polish]. Olsztyńska Szkoła Wyższa im. Józefa Rucieckiego, Olsztyn 2009, Council of Europe. Committee of experts on sport research EUROFIT. Handbook for the EUROFIT test on physical fitness. Strasbourg Dobosz J., Score tables of body height, body mass and slenderness and BMI ratios of primary school pupils [in Polish]. AWF, Warszawa Dobosz J., Score tables of Eurofit, International and Cooper tests for primary school pupils [in Polish]. AWF, Warszawa Karkosz K., Artistic gymnastics. Systematics, technology and methodology of selected exercises [in Polish]. AWF, Katowice Karniewicz J., Kochanowicz K., Selected aspects of the theoretical and practical basics of artistic gymnastics [in Polish]. AWF, Gdańsk Fjortoft I., Motor fitness in pre-primary school children: The EUROFIT motor fitness test explored on 5 7-year-old children. Pediatric Exercise Science, 2000, 12, Malina R., Baxter-Jones A., Armstrong N., Beunen G., Caine D., Daly R. et al., Role of Intensive Training in the Growth and Maturation of Artistic Gymnasts. Sports Med, 2013, 43 (9), , doi: /s

18 T. Boraczyński, M. Boraczyński, S. Boraczyńska, A. Michels, Training effects in young female gymnasts 24. Zasada M., Physical and functional preparation of the gymnasts in the long term sports training [in Polish]. UKW, Bydgoszcz Sawczyn S., Physical development and physical fitness of artistic gymnasts aged years [in Polish]. PhD thesis, AWF, Poznań Kochanowicz K., Boraczyńska L.B., Boraczyński T., Quantitative and qualitative evaluation of motor coordination abilities in gymnast girls aged 7 9 years. BJHPA, 2009, 1 (21), 57 63, doi: /v Beunen G.P., Malina R.M., Thomis M., Physical growth and maturation of female gymnasts. In: Johnston F.E., Zemel B., Eveleth P.B. (eds.), Human growth in context. Smith-Gordon, London 1999, Caine D., Lewis R., O Connor P., Howe W., Bass S., Does gymnastics training inhibit growth of females? Clin J Sports Med, 2001, 11 (4), , doi: / Mahoney C., Boreham C., Validity and reliability of fitness testing in primary school. In: Williams T. (ed.), Fitness testing and primary school children, sport and physical activity moving towards excellence. E & FN Spon., London 1992, Stupnicki R., Przewęda R., Milde K., The centile charts of physical fitness in Polish youth according to EUROFIT tests [in Polish]. AWF, Warszawa Dobosz J., The physical condition of school age girls. AWF, Warszawa Wieczorek A., Adrian J., The level of motor abilities in consideration of health conditions of selected youth groups. Stud Phys Cult Tourism, 2006, 13 (1), Baquet G., Guinhouya C., Dupont G., Nourry C., Berthoin S., Effects of short-term interval training program on physical fitness in prepubertal children. J Strength Cond Res, 2004, 4, Szopa J., Mleczko E., Żak S., The anthropomotoric basics [in Polish]. PWN, Warszawa Kraków Malina R.M., Bouchard C., Bar-Or O., Growth, Maturation and Physical Activity. Human Kinetics, Champaign Kioumourtzoglou E., Derri V., Mertzanidou O., Tzetzis G., Experience with perceptual and motor skills in rhythmic gymnastics. Percept Mot Skills, 1997, 84 (3), , doi: /pms c Raczek J., The basics of children and youth sports training [in Polish]. RCMSKFiS, Warszawa Grabowski H., Szopa J., EUROFIT, European Physical Fitness Test [in Polish]. AWF, Kraków Paper received by the Editors: April 3, 2013 Paper accepted for publication: November 26, 2013 Correspondence address Tomasz Boraczyński Olsztyńska Szkoła Wyższa im. Józefa Rusieckiego ul. Bydgoska Olsztyn, Poland boraczynski@osw.olsztyn.pl 298

19 2013, vol. 14 (4), Age dependence of thermal imaging analysis of body surface temperature in women after cryostimulation doi: /humo Agnieszka Dębiec-Bąk, Katarzyna Gruszka, Krzysztof A. Sobiech, Anna Skrzek * University School of Physical Education, Wroclaw, Poland Abstract Purpose. The aim of the study was to analyse changes in body surface temperature after a cryostimulation session in women of two different age groups. Methods. The study included 21 female university students aged 21 ± 1.8 years and 15 middle-aged women aged 57.8 ± 3.6 years. All participants were subjected to the effects of extreme low temperature in a cryogenic chamber at 120 C for 3 min. Body surface temperature measures were taken before and immediately after treatment by a thermal imaging camera. Qualitative and quantitative analysis of the captured thermographic images was performed for 12 anterior and posterior body areas in the standing position. Results. Differences in body surface temperature were found between both age groups prior to the cryostimulation treatment. Temperatures ranged from C to C in the younger group and C and C in the older group for the same body areas. Lower temperatures were observed in the older subject group for all analysed areas. After cryostimulation, greater body cooling was observed in the younger group particularly in the lower limbs. The greatest temperature reduction in both groups was observed in the lower limbs, dropping a maximum of 6.31 C, whereas the lowest variation in temperature was observed in the shoulder area by approximately 2 C. Conclusions. The results of the study showed varied distribution of body surface temperature in both age groups. Lower temperatures of the trunk and shoulders were observed in older women compared with the younger women. Greater body cooling following cryostimulation was observed in the group of younger women particularly in the area of the lower limbs. Key words: thermal imaging, age, women, whole body cryotherapy Introduction Homeostasis is a complex mechanism that involves numerous interrelated biological processes and allows the body to survive in a continually changing external environment. Thermoregulation, or the ability to maintain a constant body temperature within a normal range, depends on the maintenance of heat balance by factoring in the amount of thermal energy generated in the body through metabolic processes and the heat lost to the external environment. From a medical point of view, the most important thermoregulatory processes include heat transport via blood flow through tissue and organs such as the skin; physical phenomena including thermal convection, radiation and conductivity; and the removal of heat by evaporation (primarily in the form of perspiration). The effectiveness of these processes depends, among others, on the temperature gradient between the body s surface and the objects it is in contact with as well as the humidity and movement of surrounding air mass. The various changes that can occur in an environment may interfere with the body s ability to maintain thermal balance, especially in the elderly and children and in patients with systemic disease such as advanced heart disease or impaired sweating function [1 5]. * Corresponding author. The occurrence of hypothermia is a frequent risk in the older population as the adaptive mechanisms and physical and chemical processes determining thermoregulation are often impaired in advanced age. The vasoconstrictor response to cold is reduced in many aged individuals, leaving them more susceptible to heat loss than younger subjects when in low temperature rooms. Furthermore, when in cool rooms, aged individuals have been shown to feature reduced sensitivity to cold, noting a difference only when skin temperature decreased by 2 3 C (in young individuals by 1 C) [6, 7]. However, recent years have seen increasing interest in the effects of extremely low temperatures on the human body and, in particular, their beneficial application. This has been reflected in the broad application of low temperature methods (termed cryotherapy) in physiotherapeutic and many other fields of medicine as an effective tool in combating the various negative symptoms of illness [8 10]. However, the application of cryotherapy in older patients is often recognized as an absolute or relative contraindication. This is explained by the fundamental role thermoregulatory mechanisms play in the body after being submitted to cryogenic stimulation. The effects of cooling the body evoke the body s defence mechanism and, as such, depend on the correct functioning of these mechanisms, which may not be the case in an older population [10, 11]. However, information on the maintenance of body surface temperature in various age groups is still lacking, 299

20 A. Dębiec-Bąk, K. Gruszka, K.A. Sobiech, A. Skrzek, Age dependence of thermal imaging albeit this being a very important issue in the safe use of cryostimulation and cryotherapy methods. Therefore, the aim of this study was to analyse changes in body surface temperature as a result of a whole body cryostimulation session of women in two different age groups by thermographic examination, where thermal imaging has been cited as an objective, repeatable and non-invasive method in the observation and analysis of the changes caused by procedures using extremely low temperatures [1, 2, 12]. Material and methods The study involved 36 healthy individuals, 21 were female students from the University of Physical Education in Wrocław, Poland aged 21 ± 1.8 years and 15 middle-aged women aged 57.8 years ± 3.6 years. The research project was approved by the University s Senate Committee for Scientific Research Ethics and participants provided their written informed consent prior to enrolment in the study. A priori analysis of the two age groups somatic characteristics found statistically significant differences in body mass index (BMI). According to criteria proposed by the World Health Organisation (WHO), individuals with BMI between 18.5 and 24.9 have healthy body mass. A value between 25.0 and 29.9 is classified as overweight, while a value of 30 and above indicates obesity [13]. In the younger group, all participants were within healthy weight limits with a mean BMI of 21.3 ± 1.9. However, nine subjects in the older group (60% of the sample) were classified as overweight, with a mean BMI of 24.2 ± 3 for this group. All participants were subjected to the effects of extreme low temperature in a CR-2002/05 Cryogenic Chamber (Creator, Poland) at a temperature of 120 C for 3 min. Testing was performed at the Cryotherapy Laboratory of the Creator Private Centre for Preventive Treatment and Rehabilitation located in Wroclaw, Poland. Body surface temperature was taken before and immediately after cryostimulation treatment. Body temperature was registered with a ThermoVision A20M camera (movimed, USA) connected to a PC equipped with ThermaCAM Researcher ver. 2.8 software (FLIR Systems, USA). Thermographic imaging was performed at a distance of 2 m from the subject and included registration of minimum, maximum and mean temperature values for 12 body areas: anterior shoulder (A1), anterior trunk (A2), anterior right upper limb (A3), anterior left upper limb (A4), anterior right lower limb (A5), anterior left lower limb (A6), posterior shoulder (A7), posterior trunk (A8), posterior left upper limb (A9), posterior right upper limb (A10), posterior left lower limb (A12), posterior right lower limb (A12) (Fig. 1). Prior to the initial thermographic examination the subjects were without outer clothing (only underwear) for approximately 10 min in order to balance body temperature. The Shapiro-Wilk test was first used to assess the normality of the data and showed no evidence to reject the null hypothesis of normal distribution. Statistical characteristics of the studied parameters are presented using arithmetic mean ( ) and standard deviation (SD). Comparison of the mean values recorded for the two age groups was performed using Student s t test for independent samples. Differences between the analysed parameters were calculated by analysis of variance (ANOVA) with repeated measures, and post-hoc comparisons were made with Fisher s Least Significant Difference test (LSD). Spearman s rank correlation coefficient was calculated in order to examine the strength of associations between the variables. For all applied statistical tests, a level of p < 0.05 was considered statistically significant. Statistica ver. 9.0 (Statsoft, USA) software was used for all statistical analysis. Body area A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 Description of area Anterior shoulder Anterior trunk Anterior right upper limb Anterior left upper limb Anterior right lower limb Anterior left lower limb Posterior shoulder Posterior trunk Posterior left upper limb Posterior right upper limb Posterior left lower limb Posterior right lower limb Figure 1. Measurement fields of the 12 examined body areas 300

21 A. Dębiec-Bąk, K. Gruszka, K.A. Sobiech, A. Skrzek, Age dependence of thermal imaging Results Analysis of differences in the temperature distribution of the examined body areas found that temperatures were the highest around the trunk, lower in the upper limbs and the lowest in the lower limbs. The mean temperature values are presented in Table 1. Mean minimum and maximum temperatures prior to cryostimulation ranged from C for the anterior lower left limb (A6) to C for the anterior shoulder (A1) in the younger group and C to C in the older group for the same body areas, respectively. After treatment in the cryogenic chamber, mean temperature values for all body areas significantly decreased. Immediately after the procedure, temperatures in the younger group ranged from C for the anterior lower left limb (A6) to C for the anterior shoulder (A1), while the older group presented minimum and maximum values from C for the posterior lower right limb (A12) to C for the anterior shoulder (A1). When comparing temperature values between the younger and older group prior to cryostimulation, statistically significant differences were found in four areas: A5, A6, A7 and A8. After cryostimulation, significant differences were also noted in areas A5, A6 and A7 but also areas A1, A1 and A12 (Tab. 2, Fig. 2). Decreases in mean body temperature between the younger and older group after cryostimulation were different depending on body area (Tab. 3). The greatest temperature reduction in both groups was observed in the region of the lower limbs, reaching 6.31 C for the posterior left lower limb (A11). The smallest recorded temperature change after cryostimulation was at the posterior shoulder (A1) with a decrease of approximately 2 C. Comparisons of the younger and older groups indicated significant differences in temperature changes before and after cryostimulation in the areas of the Table 2. Mean temperature differences between the younger and older group Test area Before cryostimulation p value After cryostimulation p value A A A A A A A A A A A A Bold font denotes statistical significance at p < 0.05 Temperature [ C] Vertical bars indicate confidence intervals of 0.95 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 Before cryostimulation Group Younger Older After cryostimulation Figure 2. Graphical distribution of mean temperatures in analysed body areas Table 1. Distribution of mean temperatures of the analysed body areas Temperature before cryostimulation Temperature after cryostimulation Test area Younger n = 21 Older n = 15 Younger n = 21 Older n = 15 SD SD SD SD A A A A A A A A A A A A

22 A. Dębiec-Bąk, K. Gruszka, K.A. Sobiech, A. Skrzek, Age dependence of thermal imaging Table 3. Differences in mean temperature changes between the younger and older group Test area Temperature change following cryostimulation [ C] Younger n = 21 Older n = 15 SD Difference between groups p value A A A A A A A A A A A A Bold font denotes statistical significance at p < 0.05 SD lower limbs and shoulders, with the younger group of women showing greater loses in body temperature. ANOVA of mean temperature differences depending on body area indicated statistically significant differences. Post-hoc comparisons with the LSD test also indicated statistically significant differences albeit with more significant differences in the younger group (Tab. 4 and 5). Differences that were not statistically significant occurred primarily in symmetrical areas of the body, at analogous regions of the posterior and anterior and left and rights of the body. Discussion The benefits of cold temperatures in providing analgesic, anti-inflammatory and anti-edema effects have been utilized in many fields of medicine as well as in wellness and physiotherapy applications [1]. Full body exposure to the effects of extremely low temperatures is known to cause a thermal stress response [6]. This ini- 302 Test area Table 4. Mean temperature differences between the examined body areas in the younger group A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 Before cryostimulation A A A A A A A A A A A A After cryostimulation Bold font denotes statistical significance at p < 0.05 Test area Table 5. Mean temperature differences between the examined body areas in the older group A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 Before cryostimulation A A A A A A A A A A A A After cryostimulation Bold font denotes statistical significance at p < 0.05

23 A. Dębiec-Bąk, K. Gruszka, K.A. Sobiech, A. Skrzek, Age dependence of thermal imaging tiates many processes intended to balance energy losses as various bodily functions are dependent on maintaining a constant body temperature. These thermoregulatory mechanisms are what control heat regulation within the body. The character of body surface temperature change depends on numerous factors including the ability of skin and fatty tissue to act as an isolating layer thereby influencing heat transfer, the difference between body surface temperature and the temperature of a stimulus (e.g. ambient air temperature), its duration, and also the body s individual thermoregulatory properties [11, 14]. The thermal imaging results of the study found that temperature distribution in the examined body areas prior to cryostimulation presented the highest values around the trunk area and the lowest in the lower and upper limbs. These differences were statistically significant in both age groups. The observed differences are most likely due to the anatomical features of the analysed body areas [1, 2, 15]. Skin covering areas of the body with high vascular concentration shows greater warmth than skin lying directly on bone where there is a lack of richly vascularised tissue. Additionally, the reason for such a surface temperature gradient may be also due to the body parts thermal inertia. The limbs have a large surface area in relation to their volume, hence the greater ability to lose heat. Meanwhile, the internal organs in the trunk and abdominal cavity, which maintain core body temperature, cause these regions of the body to register higher body surface temperatures [3, 6]. The obtained results confirm the findings of other studies [2, 5, 14] and are similar to those reported by Skrzek et al. [6] on the distribution of body surface temperature in a group of healthy, middle-aged subjects, which found that the highest temperature values were observed around the shoulder area while the lowest temperatures were around the knee joints. Sobiech et al. [11] analysed the characteristics of body temperature in women aged approximately 55 years after whole body cryotherapy and found similar temperature differences in the same areas of the body. Chudecka et al. [3] and Zalewski et al. [12] also observed that the highest temperatures were in the trunk area and the lowest around the knee joints. Comparative analysis between the two age groups found that the temperatures recorded in the areas of the shoulder and trunk were lower in all analyses in the older women (with the differences statistically significant for the posterior sections). This may be the result of the physical mechanism of normothermia, which changes with age although the scope of change varies from individual to individual. Another possible explanation is that the lower temperatures in the shoulder and trunk areas in older women are associated with the fatty tissue content most probably located in these areas of the body. This can be inferred by the statistically significantly higher values of BMI in the group of older women, which qualified the majority of the sample as overweight. Similar findings were reported in other studies, indicating a link between body temperature in various areas of the body and BMI value and skinfold thickness [3, 6, 14]. This suggests that temperature distribution on the surface of the skin is dependent on body composition including lean and fat tissue content. Fatty tissue is a poorer conductor of heat than muscle and skin and causes body areas rich in fatty tissue to present lower temperatures [6, 12]. This was confirmed by Sobiech et al. [11], who found that body areas with greater fat content and thicker skinfold thicknesses presented lower temperature values. Similar observations in temperature changes in relation to different areas of the body were provided by Chudecka et al. [3]. Here, when comparing the distribution of body surface temperature in groups of men and women while taking into consideration body fat distribution, the authors showed that low temperature values were correlated to body areas of high fatty tissue content. Thermographic analysis in the present study found decreases in body surface temperature in all examined areas following cryostimulation. However, heat loss was not uniform across the body. Statistical analysis indicated statistically significant temperature differences between the younger and older age groups in the areas of the lower limbs before and after cryostimulation, the shoulder (A1, A7) before and after cryostimulation, and the posterior trunk areas (A2, A8). The study found that the younger group showed greater temperature decreases than the older group. Based on the findings of other researchers, it may be assumed that such differences between age groups may result from anatomical considerations. Additionally, this variation in body cooling may also be due to an uneven distribution of thermoreceptors on the surface of the skin. The reaction to a cold stimulus may be weakened by an uneven distribution and reduced number of receptors and also the efficiency of thermoregulatory effector mechanisms [6, 12]. In reference to other authors, it may be assumed that a stronger reaction in the area of the lower limbs and a lower temperature decrease around the trunk area in the younger age group may be the result of the increased efficiency of the circulatory system, the speed of blood flow and the thermal inertia of the mentioned areas, all of which allowed the body to react more efficiently to the extreme temperature [3, 6]. Furthermore, our findings did not confirm the notion of decreased thermoregulatory function to changes in external temperature in aged individuals. The results did not confirm concerns that advanced age is a contraindication to applying cryotherapeutic treatment. In individuals of more advanced age, there may also be an impaired vasoconstriction response to reduced temperature. This results in higher skin heat conductivity than in younger subjects, leading to greater heat loss. This may be also associated in part with the reduced 303

24 A. Dębiec-Bąk, K. Gruszka, K.A. Sobiech, A. Skrzek, Age dependence of thermal imaging efficiency of the circulatory system, which is controlled by the sympathetic nervous system and therefore be responsible for an incorrect information flow to regulatory centres [11, 14]. However, in our study no such adverse reactions were observed in the group of older women. It is possible that this group has not yet been experienced the full effects of the aging process or that the levels of obesity found among this group caused less intense cooling in the examined body areas. Our study showed symmetrical temperature distribution in analogous body areas in both age groups, which also suggests the lack of disease. Other studies have also confirmed varied albeit symmetrical temperature distribution in different areas of the body [8]. This study confirmed the safe application of temperatures of 120 C for a period of 3 minutes to aged individuals. Comparisons of the two age groups found that the younger group of women experienced greater losses in body heat. This was especially apparent in the lower limbs, with the older women featuring a significantly lower reduction in temperature, and also signifying that they are not at risk of experiencing frostbite. Analysis of the differences in body surface temperatures among the selected body areas found that the number of disparities between both age groups was reduced following the cryostimulation treatment. Statistical analysis showed that within the 66 relationships for the 12 examined body areas, 53 relationships were significantly different in the younger group prior to cryostimulation and then 57 relationships following cryostimulation. Whereas in the older group 42 relationships were significantly different prior to cryostimulation, with 56 then observed following cryostimulation. This observation indicates the differences between the groups prior to cryostimulation and its effects on narrowing this gap between different groups. Conclusions 1. The results of the study show varied distribution of body surface temperature, depending on the studied area, both in young and older women. 2. Lower temperatures of the trunk and shoulders (A1, A2, A7, A8) were observed in the group of older women in comparison with the younger group. 3. Greater body cooling following cryostimulation was observed in the group of younger women particularly in the area of the lower limbs. References 1. Cholewka A., Drzazga Z., Michnik A., Sieroń A., Wiś niowska B., Temperature effects of whole body cryotherapy determined by thermography. Thermol Int, 2004, 14, Cholewka A., Drzazga Z., Sieroń A., Monitoring of whole body cryotherapy effects by thermal imaging preliminary report. Phys Med, 2006, 22 (2), 57 62, doi: /S (06) Chudecka M., Lubkowska A., Klimek A., Szyguła Z., The impact of systemic cryotherapy on the distribution and the dynamics of temperature changes in the selected parts of body. Acta Bio-Optica Inform Med, 2008, 14, Khosla R., Guntapalli K.K., Heat-related illness. Crit Care Clin, 1999, 15 (2), Sieroń A., Cholewka A., Drzazga Z., Michnik A., Wiśniowska B., Temperature effect of whole body cryotherapy determined by thermography. Thermol Int, 2004, 14, Skrzek A., Anwajler J., Dudek K., Dębiec-Bąk A., Pilch U., Thermovision examinations of body temperature distribution after systemic cryotherapy application. Acta Bio- Optica Inform Med, 2007, 13, Westerlund T., Oksa J., Smolander J., Mikkelsson M., Thermal responses during and after whole-body cryotherapy ( 110 C). J Therm Biol, 2003, 28 (8), , doi: /j.jtherbio Cholewka A., Drzaga Z., Sieroń A., Stanek A., Thermovision diagnostics in chosen spine diseases treated by whole body cryotherapy. J Therm Anal Calorim, 2010, 102 (1), , doi: /s y. 9. Ring F., Jung A., Żuber J., New opportunities for infrared thermography in medicine. Acta Bio-Optica Inform Med, 2009, 15 (1), Yamauchi T., Nogami S., Miura K., Various applications of the extreme cryotherapy and strenuous exercise program focusing on chronic rheumatoid arthritis. Physiother Rehabil, 1981, 35 (5), Sobiech K.A., Skrzek A., Dębiec-Bąk A., Gruszka K., Socha M., Jonak W., Dynamics of body temperature changes in women due to the whole-body cryotherapy: preliminary communication. Acta Bio-Optica Inform Med, 2009, 15, Zalewski P., Buszko K., Klawe J.J., Tafil-Klawe M., Lewandowski A., Słomiński K. et al., Influence of the whole body cryotherapy on the body temperature in chosen regions in reference to the body mass index. Acta Bio- Optica Inform Med, 2009, 15, WHO, Physical Status: The use and interpretation of anthropometry (Report of a WHO Export Committee). Technical Report Series, 1995, 854, Dębiec-Bąk A., Analysis of body surface temperature and its changes under the influence of cryotherapy, systemic the infrared research. Doctoral thesis. University School of Physical Education, Wrocław Chesterton L.S., Foster N.E., Ross L., Skin temperature response to cryotherapy. Arch Phys Med Rehabil, 2002, 83 (4), , doi: /apmr Paper received by the Editors: July 17, 2013 Paper accepted for publication: November 6, 2013 Correspondence address Anna Skrzek Wydział Fizjoterapii Akademia Wychowania Fizycznego al. I.J. Paderewskiego Wrocław, Poland anna.skrzek@awf.wroc.pl 304

25 2013, vol. 14 (4), Habitual physical activity patterns of inner-city children doi: /humo Jennifer Harmon 1, Timothy A. Brusseau 2 *, Douglas Collier 1, Elizabeth Lenz 1 1 The College at Brockport, Brockport, NY, USA 2 University of Utah, Salt Lake City, UT, USA Abstract Purpose. Understanding the physical activity patterns of youth is an essential step in addressing the obesity epidemic and, ultimately, developing programs that reverse this trend. Therefore, the purpose of this study was to explore the habitual physical activity patterns of Hispanic and African-American children living in a northeastern USA urban environment. Methods. Participants included 39 inner-city children (10.5 ± 0.61 years old; 78% African American, 14% Hispanic; 85% free/reduced lunch; 20.3 ± 4.3 BMI with 45% overweight/obese). Children wore a pedometer for seven consecutive days. Means and standard deviations were calculated and Student s t test was utilized to examine difference across gender and day of the week. Results. Children averaged 9535 ± 2594 steps/day. The weekday step count mean was ± 2939 and the weekend step count was 7557 ± 4337, = Students were significantly more active during the week; t(16) = 2.38, p = Children averaged ± 2842 steps on physical education weekdays and 8338 ± 2802 steps on non-physical education weekdays. Children were significantly more active on days with physical education classes; t(30) = 4.7, p = 0.00, = Conclusions. Very few children in the current sample met daily step recommendations. Our results support previous research that suggests that the suburban built environment is more conducive to promoting physical activity than the inner city. Our sample was less active than those in the majority of other studies exploring physical activity in primary school-aged children. Our findings (compared with previous research) found reduced physical activity among African-American children, especially girls. Key words: pedometer, physical activity, children, physical education Introduction Understanding the physical activity patterns of youth is an essential step in understanding the obesity epidemic and ultimately developing programs that reverse this trend [1]. The benefits associated with regular physical activity are numerous and well documented [2]. However, these advantages are currently overshadowed by the lack of physical activity [3] among American children especially when compared with international youth. Physical inactivity is the fourth leading cause of death worldwide [1] and a primary risk factor for the leading causes of death in the United States [4]. Moreover, the prevalence of obesity in youth aged 6 to 11 has tripled over the last three decades from 6.4% in 1980 to 19.6% in 2008, with similar trends in adolescents aged 12 to 19 years [5]. The importance of understanding the physical activity patterns of youth has led to an explosion of surveillance studies exploring the habitual activity patterns of youth around the world. Over the last decade the pedometer has become an important tool in understanding the physical activity patterns of youth primarily because of its ease of use and affordability [6]. Two recent review papers [3, 6] found 43 and 31 pedometer * Corresponding author. studies examining habitual physical activity of youth worldwide, respectively. These reviews along with more recent surveillance work [7, 8] would suggest that boys accumulate between steps/weekday and girls accumulate steps/weekday. Research has also suggested that youth physical activity levels peak at age 12 [9], marking the later primary school years as especially important in this regard. Weekend physical activity has been found to range from (boys) and (girls) steps [10 12]. To date, most of these surveillance studies have primarily included Caucasian children living in suburban communities. A few recent studies have begun to explore American- Indian youth [10], Hispanic youth [13], and inner city African-American and Hispanic youth in the southwestern United States [8, 14]. In the US, a vast majority of the pedometer-based habitual physical activity research in youth has been localized to the southwest and the southeast parts of the United States, with very little attention spent on children living in urban areas and to our knowledge no studies based in the northeastern US. It is also essential that surveillance research of youth account for gender, BMI, and various physical activity segments. Therefore, the purpose of this study was to describe the habitual physical activity of children living in an inner-city environment in the northeastern United States. A secondary purpose was to explore differences across gender, BMI category (healthy weight, overweight, 305

26 J. Harmon, T.A. Brusseau, D. Collier, E. Lenz, PA patterns of inner-city children obese), and physical activity performed on weekday and weekends and on days with or without physical education. Material and methods A total 39 inner city children were invited to participate in this study with 36 obtaining parental consent and providing assent. The mean age of the children was 10.5 ± 0.61 years old. The children attended one of two 5 th grade classes in an urban primary school, located in the northeastern US. The school was chosen due to its location and an existing relationship with school personnel. All procedures were consistent with previous research [7] and approved by the University institutional review board, school district, principal, and participating teachers. Participant s parents provided their written informed consent and completed a basic demographic questionnaire (asking for children s age, gender, race, and ethnic background). School data suggested that 85% of the children were eligible for free or reduced breakfast/ lunch programs, indicating the children come from lower income families. The ethnic/racial background for the children in the study was: 78% African American, 14 % Hispanic, and 8% Caucasian. Participants had a mean BMI of 20.3 ± 4.3, with 45% being classified as overweight/obese (CDC Growth Charts, [15]). BMI was obtained by weighing (to nearest 0.1 kg) each child on a digital scale and measuring height (to nearest 0.5 cm) on a model 703 stadiometer (Seca, Germany) and using the formula: kg/m 2. The participants lived in a city consisting of people (57% ethnic minority) with a median home value of $74000 and median household income of $30367 [16]. Physical activity in this study was measured by a Digiwalker pedometer (Yamax, Japan). This pedometer was shown to produce valid and reliable data in pediatric populations [17] and is the most widely 9500 used pedometer in the research literature [6]. Prior to data 9000 collection the batteries of each pedometer were replaced 8500 and both 8000 a shake test [18] and step test [19] were performed to 7500 ensure instrument accuracy. Trained researchers provided the participants with instructions and practice sessions. The students were provided with 6000 their pedometer on Monday morning at the start of 5500 the school day on the week of data collection during class 5000 time in order to limit reactivity. To maintain consistency all children were instructed to wear the pedometer on the waist band above their right knee and told not to wear the pedometer when sleeping nor during any water activities such as bathing or swimming. Data was collected for a period of 7 consecutive days during the winter season of The children were prompted by researchers to record their daily step counts during the school week at the start of each school day. During the weekend, children were sent home with recording sheets and reminder letters for parents to ensure that they recorded their step counts for Saturday and Sunday. Each morning the researchers walked around the room observing the students, answered any questions, and looked for any outliers or unusual numbers of steps (such as below 1000 or above 30000). Any extreme or unverified step values (< 1%) were eliminated. As a validity check, the children were asked to answer eight simple questions each morning (e.g., did the child wear the pedometer the entire day or did they have a physical education class the day before). Statistical analysis included calculating means and standard deviations. Student s t test was utilized to examine difference across gender and day of the week. ANOVA was utilized to examine differences across BMI categories. SPSS ver software (IBM, USA) was utilized for all analyses. A minimum of two days of data from each participant were required to be included in the study [12]. Results The children averaged 9535 ± 2594 steps over the 7 days (5 weekdays and 2 weekend days) of data collection. The weekday step count mean was ± 2939 and on the weekend was 7557 ± 4337, = The paired samples t test revealed that students were significantly more active during the week; t(16) = 2.38, p = The means for the weekday, weekend, and seven-day week step counts for the children by gender are illustrated in Figure 1. The differences in step counts between boys and girls for weekdays, weekend days, and the seven-day week was 1756, 681, and 1409 steps, respectively, with boys performing more steps in each case. Independent t tests revealed that the boys and girls were similarly active across all three time categories: weekday steps t(30) = 1.86, p = 0.07, = 1756; weekend steps t(15) = 0.31, p = 0.76, = 681; and seven-day week t(30) = 1.56, p = 0.13, Girls (n = 18) Boys (n = 14) Weekday 8000 Weekend Seven-day week Weekday Weekend Seven-day week Note: children were significantly more active during the week (p < 0.05); there were no significant differences by gender Figure 1. Weekday, weekend, and seven-day week step counts Girls (n = 1 Boys (n = 306

27 J. Harmon, T.A. Brusseau, D. Collier, E. Lenz, PA patterns of inner-city children = Although not significant F(2,29) = 0.10, p = 0.90, children in the healthy weight category averaged slightly more steps/day (9707 ± 2309) than their overweight and obese (9275 ± 3123) peers. Levene s test verified the equality of variances in the sample (p > 0.05). Children averaged ± 2842 steps on weekdays with physical education classes and 8338 ± 2802 steps on non-physical education weekdays. Paired samples t test indicated that children were significantly more active on physical education days; t(30) = 4.7, p = 0.00, = 2272 steps. Boys averaged ± 2405 and girls averaged ± 3356 steps ( = 1457) on physical education days. The mean step count for boys on non-physical education weekdays was 8982 ± 2990 and 7873 ± 2645 for girls ( = 1109). Boys increased their step count by 2651 and girls by 2303 on physical education days. Discussion This study explored the habitual physical activity patterns of primary school-aged children living in a northeastern United States city. The findings suggest that the present youth are falling well short of the daily recommendation of steps/day [20]. Only 17% of the current sample averaged steps/day, suggesting that this population of boys and girls needs to increase their daily step count on average by 2700 and 3100 steps, respectively. When compared with the physical activity patterns of other American children, the current sample lags well behind children living in the midwestern [21] and southwestern parts of the US [7, 22]. The present group of children did accumulate similar steps/day when compared with children living in the southern US [23]. When compared with previous work on inner-city children in the southwestern US [14], boys accumulated approximately 1600 less steps/day while girls accumulated a similar number of steps (9200 with 9500). Previous findings [24] have suggested that both single-parent homes and socioeconomic status may play a role in limiting children s physical activity. Furthermore, parental modeling of physical activity may be especially important for girls [25]. In our study, approximately half of the participants came from single parent households and 85% qualified for free or reduced meals. It is also possible that children in urban single-parent homes have more home responsibilities and less disposable income to engage in and participate in structured physical activities compared with children from suburban and dual/married-parent homes. Another reason for the low step counts may also be explained by safety concerns in the neighborhood [26]. Gender differences in this study (although not significant) support previous research that suggests that boys are generally more active than girls [7]. Similarly, the results (although not significant) are also in line with BMI differences found in previous studies suggesting that overweight and obese children are less active than healthy-weight peers [7]. The lack of significance in the current sample is likely due to the small sample size. The present participants were significantly less active on the weekend, which supports previous research [10, 11] that found that children fail to make up for physical activity accumulated while attending school. The low physical activity patterns of youth (especially on weekends) highlight the need for additional low cost and safe activity programs on weekends. Physical education was extremely important for the current sample and appears to have had a much greater impact on the daily activity patterns of youth when compared with previous studies [10, 11]. Prior research has suggested that physical education had the potential to increase daily activity by steps/day. In the current study, physical education impacted habitual physical activity by 2500 steps. It would appear that increasing the frequency of quality physical education could have a significant impact on daily physical activity. Brusseau et al. [7] found that as the number of days of physical education increases so do children s daily physical activity levels. Weather may have impacted the habitual physical activity of the current sample. Data were collected in the winter in the northeastern US. Although temperatures were unseasonably warm during data collection, fields and parks remained unusable. Previous research has found that youth tend to be less active (especially outside of school) during winter months [27, 28]. Beighle et al. [27] found that southeastern US children decreased their out-of-school activity by 1153 steps during the winter. Brusseau et al. [28] found that southwestern American-Indian children decreased their school physical activity by steps during the winter. These numbers are especially alarming since the climate in the southeast and southwestern parts of the US can be considered mild when compared with the northeast. Recent studies have highlighted various time segments that hold potential both in and out of school for increasing physical activity. For example, Beets, Huberty, and Beighle [29] found that children in a two-hour afterschool program might expect to accumulate nearly 3000 steps. Daily free periods (or extra free periods) during school had the potential to add over 1000 steps [7]. Furthermore, classroom activity breaks may add extra physical activity. Bershwinger and Brusseau [30] found that low-cost, classroom-based activity breaks/lessons might increase daily physical activity by steps. Lastly, studies that have explored active transportation in urban areas found that students that walked to school were significantly more active than bus/car riders [14]. To our knowledge this is the first study to explore the habitual step counts of northeastern US children and one of very few studies that have focused on the physical activity patterns of inner-city children. However, the small sample size is worth noting as it may limit generalizability across other inner-city samples. 307

28 J. Harmon, T.A. Brusseau, D. Collier, E. Lenz, PA patterns of inner-city children Future research with larger sample sizes from multiple cities is needed to confirm these findings. Furthermore, it is also important to address the fact that pedometers do not account for physical activity intensity or context, albeit their ease of use and affordability. Conclusions Very few children in the current sample met their daily step recommendations. Our results support previous research that suggests that suburban-built environment appears more conducive to promoting physical activity when compared with urban areas [31]. Our sample was less active than most other studies exploring physical activity in primary school-aged children. Our findings are also supported by Johnson, Brusseau, Vincent-Graser et al. [8], who found reduced physical activity among African-American children and youth, especially girls, and among children and youth living in urban areas. Physical education appears to be an important element to the daily physical activity levels of this population, suggesting the need for increased frequency of physical education classes and that increased physical activity opportunities are warranted on weekends. References 1. Kohl H.W., Craig C.L., Lambert E.V., Inoue S., Alkandari J.R., Leetongin G. et al., The pandemic of physical inactivity: Global action for public health. Lancet, 2012, 380 (9638), , doi: /S (12) Sothern M.S., Loftin M., Suskind R.M., Udall J.N., Blec ker U., The health benefits of physical activity in children and adolescents: implications for chronic disease prevention. Eur J Pediatr, 1999, 158 (4), , doi: /s Beets M.W., Bornstein D., Beighle A., Cardinal B.J., Morgan C.F., Pedometer-measured physical activity patterns of youth: a 13-country review. 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J Phys Act Health, 2010, 7 (3), Tudor-Locke C., Craig C.L., Beets M.W., Belton S., Cardon G.M., Duncan S. et al., How many steps/day are enough? for children and adolescents. Int J Behav Nutr Phys Act, 2011, 8 (1), 78, doi: / Brusseau T.A., Kulinna P.H., Tudor-Locke C., Ferry M., Daily physical activity patterns of children living in an American Indian community. J Phys Act Health, 2013, 10 (1), Brusseau T., Kulinna P., Tudor-Locke C., van der Mars H., Darst P., Children s step counts on weekend, physical education, and non-physical education days. J Hum Kin, 2011, 27 (1), doi: /v Rowe D., Mahar M., Raedeke T.D., Lore J., Measuring physical activity in children with pedometers: Reliability, reactivity, and replacement of missing data. Pediatr Exerc Sci, 2004, 16 (4), Oh H.J., Hannon J., Williams D.P., Physical activity differences by birthplace and sex in youth of Mexican heritage. J Phys Act Health, 2012, 9 (4), Johnson T.G., Brusseau T.A., Darst P.W., Kulinna P.H., White-Taylor J., Step counts of non-white minority children and youth by gender, grade level, race/ethnicity and mode of school transportation. J Phys Act Health, 2010, 7 (6), Ogden C.L., Kuczmarski R.J., Flegal K.M., Mei Z., Guo S., Wei R. et al., Centers for Disease Control and Prevention 2000 growth charts for the United States: improvements to the 1977 National Center for Health Statistics version. Pediatr, 2002, 109 (1), 45 60, doi: / peds U.S. Census Bureau, State & County Quickfacts: Monroe County, N.Y. Retrieved January 25, 2013, Available from Barfield J.P., Rowe D.A., Michael T.J., Interinstrument consistency of the Yamax Digi-Walker pedometer in elementary school-aged children. Meas Phys Educ Exerc Sci, 2004, 8 (2), , doi: /s mpee0802_ Vincent S.D., Sidman C.L., Determining measurement error in digital pedometers. Meas Phys Educ Exerc Sci, 2003, 7 (1), 19 24, doi: /S MPEE0701_ Tudor-Locke C., Williams J.E, Reis J.P, Pluto D., Utility of pedometers for assessing physical activity: convergent validity. Sports Med, 2002, 32 (12), , doi: / Colley R.C., Janssen I., Tremblay M.S., Daily step target to measure adherence to physical activity guidelines in children. Med Sci Sports Exerc, 2012, 44 (5), , doi: /MSS.0b013e31823f23b Laurson K.R., Eisenmann J.C., Welk G.J., Wickel E.E., Gentile D.A., Walsh D.A., Evaluation of youth pedometer-determined physical activity guidelines using receiver operator characteristic curves. Prev Med, 2008, 46 (5), , doi: /j.ypmed Brusseau T.A., Tudor-Locke C., Kulinna P.H., Are children meeting any of the suggested step recommendations? Biomed Hum Kin, 2013, 5 (1), 11 16, doi: /bhk Beighle A., Alderman B., Morgan C.F., Le Masurier G., Seasonality in children s pedometer-measured physical activity levels. 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29 J. Harmon, T.A. Brusseau, D. Collier, E. Lenz, PA patterns of inner-city children 25. Davison K.K., Cutting T.M., Birch L.L., Parents activity-related parenting practices predict girls physical activity. Med Sci Sports Exerc, 2003, 35 (9), , doi: /01.MSS C. 26. Carver A., Timperio A., Crawford D., Playing it safe: The influence of neighbourhood safety on children s physical activity. A review. Health Place, 2008, 14 (2), , doi: /j.healthplace Beighle A., Erwin H., Morgan C.F., Alderman B., Children s in-school and out-of-school physical activity during two seasons. Res Q Exerc Sport, 2012, 83 (1), , doi: / Brusseau T.A., Kulinna P.H., Kloeppel T., Ferry M., Seasonal variation of American Indian children s school-day physical activity. Biomed Hum Kin, 2012, 4, 76 81, doi: /v z. 29. Beets M.W., Huberty J., Beighle A., Physical activity of children attending afterschool programs: Research-and practice-based implications. Am J Prev Med, 2012, 42 (2), , doi: /j.amepre Bershwinger T., Brusseau T.A., The impact of classroom activity breaks on the school-day physical activity of rural children. Int J Exerc Sci, 2013, 6 (2), Sandercock G., Angus C., Barton J., Physical activity levels of children living in different built environments. Prev Med, 2010, 50 (4), , doi: /j.ypmed Paper received by the Editors: September 6, 2013 Paper accepted for publication: November 26, 2013 Correspondence address Dr. Timothy A. Brusseau University of Utah 250 S 1850 E, RM 205 Salt Lake City, UT 84112, USA tim.brusseau@utah.edu 309

30 2013, vol. 14 (4), Preschool attendance as a factor in the motor skill development of children doi: /humo Magdalena Rokicka-Hebel University of Physical Education and Sport, Gdańsk, Poland Abstract Purpose. The purpose of this study was to evaluate the motor skills of children who had already attended one year of preschool or had just begun their education. Methods. A total of 286 five- and six-year-old children were recruited from different preschools (eight preschools and three primary school preschool programs) in Gdańsk, Poland. A test battery was designed based on the children s preschool physical education curriculum and the motor skills that should be acquired at this age. The analyzed motor tasks included: 1) walking on a balance bench, 2) crawling on an inclined balance bench, 3) running then jumping over an obstacle with one leg, 4) catching and throwing a ball over an obstacle, 5) throwing a ball against the wall and catching it, 6) climbing on a gymnastic ladder, 7) jumproping. The children were tested twice in test-retest conditions, at the beginning and end of the school year. Results. The children showed the lowest level of skills in throwing, catching, and bouncing a ball against the wall and jumproping. Conclusions. No significant differences were identified as to children s physical abilities or between the 5-year-olds and 6-year-olds either beginning or continuing preschool. Key words: infancy age, motor skills, physical activity Introduction One of the first scientific studies on the importance of early childhood comes from the work developed by Freud on how personality disorders arise at this point in time. According to Freud, the source of psychological problems in later life may stem from a troubled childhood. More recent research has further specified the interpretations of Freud. In clinical studies conducted on children from birth until reaching maturity, Erikson stated that childhood is a stage where a human being begins to emerge as person, a place in which our individual talents and shortcomings slowly but noticeably begin to develop and be revealed [1, pg. 62]. Many psychologists believe that the early school years, beginning from the second until the fifth year of life, belong to one of the most important or even the most important developmental periods of life. Functional analyses of these phases have reached the same conclusions, where it is undoubtedly a period of life in which our most basic foundations are organized into a behavioral structure [1, pg. 63]. In this regard, the preschool age, spanning from the third year of life until beginning school, stands as an early precursor for future development. However, the beginning of this developmental phase is difficult to determine. It has been assumed that it begins when a child is able to freely move (walk and run), communicate with others by talking, has all of their deciduous teeth, and is independent in many daily self-care activities [2]. According to Hurlock, the preschool age can also be labeled as early childhood, covering the period between the second and sixth year of life when a child begins to find ways to assume self control over their environment and wants to acquire social skills [1]. However, one of the most dynamic phases of motor development and child mobility occurs during early childhood (up to fifth/sixth year of life). One of the features behind a small child s motility is the strong need to satisfy their movement hunger and hyperactivity. In terms of motor skills, children aged five years are considered to enter a perfected state at the preschool age or the golden age of childhood. This undoubtedly is a period of time that needs to be taken advantage of and cannot be wasted. This is especially important for preschool teachers and parents. At this age, children possess the ability to perform accurate movement patterns, therefore it is very important for them to not only learn correct form but also enrich their interest in physical activity through the use of games and appropriate equipment and organization. Children have the irresistible urge for physical activity, showing this in ways impossible to miss. However, children associate physical activity with spontaneous, wild movements that can be changed at will and adapted to whatever purpose. As a result, the proper physical development of children is grounded on educating their psychomotor capabilities and furthering their motor skills. This can stimulate children to engage in various forms of physical activity whether independently or under supervision. Supervised physical activity should be tailored to children s capabilities and match their needs and requirements rather liberally depending on their motor abilities, creativity, and developed personality so as to not discourage them in case of failing to perform the outlined tasks. Furthermore, physical activity is only 310

31 M. Rokicka-Hebel, Preschool attendance on motor skill development effective when its frequency and intensity are adequate to the physical predispositions and capabilities of children at a given developmental stage. Researchers commonly agree that the proper development of motor skills in children is associated with improved health, intellectual development, and social skills and leads to increased independence, better possibilities of gaining valuable life experience, and improved self-esteem [1, 2]. An appropriate level of physical activity combined with positive emotions experienced in childhood and adolescence can create a foundation for lifelong physical activity. Woynarowska [3] argues that low levels of spontaneous physical activity in early childhood may be a sign of a developmental disorder or health condition, while limiting spontaneous physical activity can quite early and permanently suppress the need for physical activity, disrupt physical development, and create a health risk in later life. She feels these limitations ought to be considered as a form of child neglect and, in extreme cases, as a sign of abuse [3]. In a similar vein, if leading a healthy lifestyle during childhood is a deciding factor in maintaining it in later life, it can be assumed that other psychological and behavioral factors revealed at a young age will also be transferred into adult life. This transfer can be understood as various factors maintaining a relative position of influence over time. In other words, an individual with a risk factor with a high relative risk in childhood would have the same relative risk as an adult [4, 5]. Also of note is how adequate physical activity in childhood may provide beneficial biological and behavioral effects later in adulthood [6]. Physically active and fit children, who also have physically active parents, have been found to have a greater chance of maintaining a physically active lifestyle in adult life [7 9]. Regular physical activity in childhood is known to have a significant impact on immediate and long-term health. Current research on the physical activity of children recommends at least 60 min or more of moderate to intensive exercise per day [10]. Studies have found that the physical activity of children lasts in 5 10 min sequences [11]. Others suggest that the majority of physical activity by children is performed intermittently [12], rarely lasting more than 5 10 min [13, 14] and predominantly less than 5 min [15]. Other studies have observed that children aged 6 10 years showed a mean duration of uninterrupted physical activity of 20 s [16, 17]. These attributes should be taken into consideration as other recommendations stress that children should perform physical activity focused on the development of the locomotor system (induced by intensive physical effort) at least twice a week [18]. The preschool years are marked by an intensive development of physical fitness and improvement of movement technique. Movements start to become more precise, economical, and expedient. Every year brings significant differences in the technical level of performing such activities as running, throwing, and jumping [2]. According to Przewęda [2], children aged 3 4 years have the capability to walk, run, climb, overcome easy obstacles, jump, throw, hit, move, perform somersaults, roll, and perform activities that require a modicum of balance or rhythmic movement. All of these activities at approximately four years of age begin to improve, becoming more fluid and precise, increasingly faster and more agile, and become more purposeful and predictable. She described this period when ( ) a child begins to construct new movement patterns, where new skills begin to emerge and later on can be combined to perform activities that require simultaneous movements that form the so-called movement combinations (space chords) [2, pg. 159]. By the fourth and fifth year of life, the development process significantly accelerates, with changes that can be described as a developmental leap. This period is marked by the fastest motor development with greatly improved coordination, where activities that have been mastered begin to show rhythm, fluidity, and harmony in both the entire movement and its phases, although there is still a lack of flexibility, precision, and anticipation. The harmony of locomotor movements is revealed around the age of five years, which is sometimes referred to as the golden age of motor skill development or the preschool period of equilibrium [2, pg. 160]. Speed, agility, and overall strength increases, followed by the development of voluntary movements, specialized manual tasks, and deliberate and precise movements. Children begin to run more quickly and rapidly in a ways more economical and accurate, where by the age of five they are able to race and chase each other. With growing maturation the respective centers of the cerebral cortex and neuromuscular system significantly advance the ability to maintain balance. Five-yearolds are able to stand on one leg for a considerable length of time, they can combine walking on a balance bench while crossing obstacles, move objects with only one foot, or perform the limbo. They are able to stand with one foot behind the other on their toes or perform a squat without using their hands. Furthermore, motor development in 5-year-olds also includes significant advances in the ability to throw and catch objects. Children at this age are able to throw and catch a bag or ball while not only standing in place but also walking or even running. They can catch balls thrown to them, although the catching movement frequently requires the use of their whole body. At six years of age, children feature even more rapid progress in motor skill development, becoming stronger and more efficient. They are characterized by greater movement dynamics, fluidity, and freedom, while at the same time their movement is properly matched to the task at hand and, therefore, becomes more economical. The behavior of 6-year-olds begins to show predictive 311

32 M. Rokicka-Hebel, Preschool attendance on motor skill development movements, such as shifting the trunk forward and extending the arms in order to catch a ball or when walking backwards. This period also features the automation of simple movements such as walking, running, or hopping. This promotes further movement fluidity and freedom, allowing 6-year olds to easily combine them with other movements such as performing a running throw. Sixyear-olds at this age can smoothly perform combination movements and can be motivated to perform more difficult exercises requiring greater effort. Throwing movements by 6-year-olds are now characterized by a smooth combination of the preparatory phase with the main throwing phase. They are also able to aim at targets 5 m away. Catching ability also improves, with 6-year-olds able to use their hands when catching objects without moving the entire body. However, activities requiring both catching and throwing may still pose difficulties. With the growth of muscular strength and coordination skills, 6-year-olds exhibit greater freedom, dynamics, and fluidity when jumping and hopping. Additionally, when playing, children also begin to spontaneously introduce elements of resistance (pushing or pulling). It is deemed that physical activity is a fixed component of human behavior throughout life. Research conducted during 2 3 year periods in infancy, adolescence, and adulthood have shown a fairly constant level of of physical activity [19]. It needs to be noted that the preschool age should be a period of conscious education by adults on the not yet fully formed attitudes of children on how their bodies are susceptible to positive and negative influences. This is a time when opportunities to form basic concepts on good health, fitness, and immunity to diseases should not be wasted. As a result, education in this regard should begin from the earliest years of life. Extensive research on the physical fitness of preschool children was conducted by Sekita between [20, 21]. She composed a battery of fitness tests in 1977 to assess motor development, which consisted of five tests: the standing long jump, throwing a 1 kg medicine ball, performing a 4 5 m shuttle run, running 20 m, and hitting targets on a special board within 20 s. On the basis of her results, it was concluded that age is a key factor in the development of physical fitness between 3 7 years of age and that changes between age groups are very clear. Sekita also found that children s motor skills developed at unequal rates, with agility developing the fastest and then speed, power and strength [20, 21]. Ugodowska in 1991 used Sekita s test battery to measure the physical fitness and mobility of 91 six-yearolds attending preschool [22]. The results allowed for the conclusion that physical education classes in preschool largely affect the motor skill learning characteristics of children and that a low level of its development was often evidence of neglect on the part of the family. The aim of this research was to clarify the relationship between the motor skill levels of children attending preschool programs and the length of their attendance in preschool. The research problem that was posed was: are children beginning preschool at the age of 5 or 6 years characterized by lower motor skill levels than their similar-aged peers who had been attending preschool earlier (one year or more)? With this in mind, the following research questions were formulated: 1. What is the motor skill level of children who are beginning preschool at the age of 5 or 6 years and what is the level of children in the same age groups who have been attending preschool at least one year earlier? 2. Was there an improvement in the motor skill level of 5- and 6-year-olds after attending preschool for a year? 3. Was there an improvement in the motor skill level of 5- and 6-year-olds who were continuing their education in preschool? 4. Did teachers during the school year teach physical exercises similar to the ones used in physical fitness test batteries? Material and methods The population sample was chosen from preschools belonging to the Board of Education of Gdańsk, Poland. Preschools were deliberately chosen after analysis on the physical education environments they possessed, including preschools with both good and poor infrastructure. The final sample consisted of three public and two private preschools with good infrastructure for physical activity, two public and one private preschool with poor infrastructure, and three primary schools offering preschool programs. The study was conducted on a total of 11 preschools all located within the city the Gdańsk, Poland in September/October 2007 and again in May/ June All children attending the preschools were selected for inclusion. Written informed consent was provided by their parents or guardians, and the study procedure was performed in accordance with the guidelines outlined by the local ethics committee. The total sample included 286 five- and six-year-old children who were divided into two groups, those who had just begun attending preschool and those who were continuing their education (having previously attended preschool for at least a year). Analysis was first made of the activities logs and educational programs of the selected preschools and how motor development was tested by the preschools or what types of motor skills children were considered to be necessary based on the preschools educational programs The aim of analyzing the preschool programs was to assess what motor skills the children should possess. On this basis could a relevant test battery be designed 312

33 M. Rokicka-Hebel, Preschool attendance on motor skill development Table 1. Number of children included in the study Attendance history Beginning preschool Continuing preschool 5-year-olds 6-year-olds 5-year-olds 6-year-olds Total Number of children to determine the motor skill development of the participants. In the surveyed preschools a total of nine different preschool educational programs were being implemented. However, all had content that was similar to one another and allowed for the development of a motor skill test that would be universal for all examined children. It was decided that an assessment of the children s motor skills would be qualitative in nature and designed to determine the proportion of children that would have difficulties in the correct execution of elementary (for this age group) motor tasks. In this regard, a pilot study was performed to standardize the grading criteria used to evaluate the motor tasks. It was determined to assign scores from 0 and 1, where: 1 correctly performed the task or with a small error that had no effect on overall task execution, 0.5 performed the task with a large error, and 0 was unable to perform the task at hand. All trials were performed by the author in a school gymnasium or, in their absence, at a classroom suitable for performing all tests. All testing was performed at approx. 10:00 for each preschool on two separate occasions (test retest), Test1 at the beginning of the school year in September/October 2007 and Test2 at the end of the school year in May/June Each motor task was demonstrated by the assessor before testing. The children were dressed in sports attire and all tests were performed in running shoes except for Tests I and II. The motor tasks that were assessed are outlined below: Test I Walking on a balance bench Location: school gymnasium Equipment: 3 m bench Execution: Walking on a thin balance bench and performing a 360º rotation at the middle and maintaining correct placement of the feet Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: lost balance and touched the ground (max. two times) squatted to regain balance (max. two times) walked very slowly 0 pt. unable to perform the task Test II Climbing a gymnastics ladder Location: school gymnasium Equipment: gymnastics ladder Execution: Climbing and descending 2 m on a wall bar while correctly grabbing the rungs with diagonal movement of the arms and legs Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: climbed with incorrect leg placement lack of diagonal movement with arms and legs 0 pt. unable to perform the task Test III Crawling on an inclined gymnastics bench Location: school gymnasium Equipment: 3 m bench Execution: Crawling on an inclined gymnastics bench attached to an 80 cm ladder Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: stopped (max. two times) crawled very slowly 0 pt. unable to perform the task Test IV Running and jumping over an obstacle with one leg Location: school gymnasium Equipment: 5 m rubber rope Execution: Running for a distance of 5 m and jumping over a rubber rope suspended 20 cm above the ground placed 3 m from the start Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: made contact with the rope stopped in front of the obstacle and stepped over the rope jumped with both feet 0 pt. unable to perform the task Test V Catching and throwing a ball over an obstacle Location: school gymnasium Equipment: 20 cm rubber ball and rope Execution: Catching the ball thrown from a distance of 1.5 m with both hands and throwing it over a rope placed 1.5 m in front of the child at a height of 1.5 m using an overhead or one-handed throw or chest pass. Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: unable to catch the ball ball went under the rope or did not reach the obstacle performed an underhand throw 0 pt. unable to perform the task 313

34 M. Rokicka-Hebel, Preschool attendance on motor skill development Test VI Throwing a ball against a wall and catching it Location: school gymnasium Equipment: 20 cm rubber ball Execution: Throwing the ball with both hands using a chest pass against a wall at a distance of 1 m and catching the ball with both hands (one cycle); required to perform a minimum of four complete cycles Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: incorrect catch incorrect throw 0 pt. unable to perform the task Test VII Jumproping Location: school gymnasium Equipment: Jump rope with a length of 170 cm (adjusted to each child s height) Execution: Performing a minimum of three jump ropes in any way Scoring: 1 pt. correctly performed 0.5 pt. performed with a large error: jumped and stopped jumps performed fluidly, but stopped after two jumps and then continued 0 pt. unable to perform the task Results The task that was correctly performed by the highest percentage of children was Test III, or running and jumping over an obstacle with one leg. Two of the groups of children, 5- and 6-year-olds beginning preschool, performed this test with 100% success at the end of the school year (Test2). A high percentage of children also correctly performed Test II, or crawling on an inclined gymnastics bench. Here, the group of 5-year-olds beginning preschool correctly completed the task during Test2. The tests with the highest percentage of children failing to complete the task were Tests VII and V, or jumproping and throwing a ball against a wall and catching it, respectively. The lowest presented motor skill level in six of the seven motor tasks was among the 5-yearold children beginning preschool during testing at the beginning of the school year (Test1). Overall, the highest amount of correctly performed tasks by the largest number of children in each of the groups was by 6-year-olds continuing preschool during Test2 in climbing a gymnastics ladder, throwing a ball against a wall and catching it, and jumproping, which were tasks that were completed by only 13.6% of the total sample. Figures 1 14 illustrate the motor skill levels of the 5- and 6-year-old children beginning or continuing preschool in completing each of the seven tasks: Test I Walking on a balance bench Among the 5-year-olds beginning preschool, after a year of attending preschool no improvement in the performance of this task was observed. Among the 6-yearolds beginning preschool, testing performed after the school year (Test2) had four more children correctly finishing the task (Fig. 1B). Among the 5-year-old children continuing preschool, in Test2 more children managed to perform this task No.of children B A No. of children No. of children No. of children B A year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 1. Test results of walking on a balance bench before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool 5-year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 2. Test results of walking on a balance bench before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) continuing preschool 314

35 M. Rokicka-Hebel, Preschool attendance on motor skill development without a large error. At the same time, there were six less children that were unable to perform this task (Fig. 2A). Six-year-olds continuing preschool showed a slight improvement in this task, with seven additional children being able to correctly perform this task in Test2 (Fig. 2B). Test II Climbing a gymnastics ladder After attending preschool for a year, the 5-year-olds beginning preschool who were unable to perform this task in Test1 progressed enough to be able to perform it with a large error in Test2 (Fig. 3A). Similarly, the 6-yearolds beginning preschool, after attending school for a year, did not show a great amount of progress in this test. One child who was unable to climb the gymnastics ladder in Test1 performed the task with a large error in Test2, while another child who performed the task flawlessly in Test1 performed the task with an error in Test2 (Fig. 3B). Among the 5-year-olds continuing preschool, improvements were seen across the entire group, with eight additional children being able to correctly perform the task in Test2 (Fig. 4A). The mean motor skill level of 6-year-olds continuing preschool slightly improved in the wall bar task in Test2. Additionally in Test2, there were no more children unable to perform the task and three additional children were able to perform the exercise without error (Fig. 4B). Test III Crawling on an inclined gymnastics bench Besides one child, all of the 5-year-old children beginning preschool correctly performed this motor task A No. of children B 10 No. of childreni year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 3. Test results of climbing a gymnastics ladder before (Test1) and after (Test2) the school year for 5-yearolds (A) and 6-year-olds (B) beginning preschool A No. of children B No. of children year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 4. Test results of climbing a gymnastics ladder before (Test1) and after (Test2) the school year for 5-yearolds (A) and 6-year-olds (B) continuing preschool A No. of children B No. of children year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 5. Test results of crawling on an inclined gymnastics bench before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool (Fig. 5A). Additionally, almost all of the 6-year-olds beginning preschool correctly performed this test. Only two of the 5-year-olds continuing preschool in Test1 were unable to perform this task. However, in Test2, five children performed the exercise with an error (Fig. 6A). Among the group of 6-year-olds continuing preschool, eight children in Test1 performed the text 315

36 M. Rokicka-Hebel, Preschool attendance on motor skill development A No. of children B No. of childreni year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 6. Test results of crawling on an inclined gymnastics bench before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) continuing preschool with an error. In Test2, only one child was unable to perform the exercise (Fig. 6B). Both the 5- and 6-year-olds beginning and continuing preschool showed a high motor skill level in crawling on an inclined gymnastics bench. Test IV Running and jumping over an obstacle with one leg Only two 5-year-old children beginning preschool were unable to run and jump over an obstacle with one leg in Test1 (Fig. 7A). After attending preschool for a year, all of the 5- and 6-year-olds correctly performed this task (Test2). An improvement was noted in Test2 among 5-yearolds continuing preschool, where only five children completed the task with an error; the rest correctly performed the test (Fig. 8A). Only two of the 6-yearolds continuing preschool did not complete this task, while 10 our of the group of 140 children performed this test without error in the beginning of the school year (Test1). In Test2, seven less children finished the task with a large error and there were no children who were unable to perform the task (Fig. 8B). Test V Catching and throwing a ball over an obstacle The majority of 5-year-olds beginning preschool performed the test measuring catching and throwing a ball over an obstacle with a large error. After attending preschool for a year, only three children were able to correctly perform this task (Fig. 9A). In the case of A No. of children B No. of children year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 7. Test results of running and jumping over an obstacle with one leg before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool A No. of children B No. of children year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 8. Test results of running and jumping over an obstacle with one leg before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) continuing preschool 6-year-olds continuing preschool, performance worsened in this group in Test2 (Fig. 9B). There were four less 5-year-olds continuing preschool that correctly performed this task at the end of the school (Test2). At the same time, four children who did not perform the task in Test1 were able to perform the test with a large error (Fig. 10A). No improvement was seen in the group of 6-year-olds continuing pre- 316

37 M. Rokicka-Hebel, Preschool attendance on motor skill development A No. of children B No. of children year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 9. Test results of catching and throwing a ball over an obstacle before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool A No. of children B No. of children year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 10. Test results of catching and throwing a ball over an obstacle before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool school. Five children who were unable to complete the task in Test1 performed the test with a large error in Test2. However, four children who correctly performed the task in Test1 completed the test in Test2 with a large error (Fig. 10B). Test VI throwing a ball against a wall and catching it Testing performed at the beginning of the school year found only one 5-year-old beginning preschool that was able to perform the task albeit with a large error, the rest of this group failed to complete the task. A slight A No. of children B 10 No. of children year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds beginning preschool Test 1 Test 2 Unable to perform Performed with large error Correctly performed Figure 11. Test results of throwing a ball against a wall and catching it before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool No. of children A B No. of children year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed 6-year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 12. Test results of throwing a ball against a wall and catching it before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) continuing preschool 317

38 M. Rokicka-Hebel, Preschool attendance on motor skill development improvement was noted in Test2, with three additional children able to perform the task with a large error (Fig. 11A). Among the 6-year-olds beginning preschool, testing performed after attending school for a year had only one child that was able to correctly throw and catch a ball (Fig. 11B). Among 5-year-olds continuing preschool, the number of children who performed the task with a large error increased by 36 in Test2. Only one child tested at the end of the school year correctly performed the task (Fig. 12A) Among 6-year-olds continuing preschool there were 13 more children who correctly performed the task (Fig. 12B). Test VII Jumproping Five-year-old children beginning preschool were unable to perform the jump over a jump rope exercise. Even after a year of school, only one child was able to correctly jump rope (Fig. 13A). Among 6-year-olds beginning preschool, only two children correctly performed the task (Fig. 13B). Among the year-olds continuing preschool, only one was able to correctly perform the task in Test1 and two in Test2 (Fig. 14A). Among 6-year-olds continuing preschool, seven additional children correctly performed the jump rope test in Test2 (Fig. 14B). A 15 No. of children year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed A No. of children year-olds continuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed B No. of children year-olds beginning preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 13. Test results of jumproping before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) beginning preschool B No. of childreni year-olds cotinuing preschool Test 1 Unable to perform Test 2 Performed with large error Correctly performed Figure 14. Test results of jumproping before (Test1) and after (Test2) the school year for 5-year-olds (A) and 6-year-olds (B) continuing preschool Table 2. Analysis of physical activity logs of the selected preschools for exercises performed within the scope of the applied test battery and based on the preschool curriculum Preschool Balance bench exercises Wall bar exercises Crawling Running with jumping Ball exercises Jump rope exercises 1 2x 2x 2 3 1x 4 1x 1x x 8 1x

39 M. Rokicka-Hebel, Preschool attendance on motor skill development Analysis of the physical activity logs of the selected preschools at the end of the school year in June found that out of the eleven schools only five had at least once conducted exercises similar to the tasks assessed by the test battery (which in turn was based on the preschool physical education curriculum). In six preschools no exercises of a similar nature were conducted. Although all of the participating children s teachers were informed that the battery was to be re-administered at the end of the school year, it was found that only a few of the exercises were taught by teachers throughout the school year. Examination of the logs found that those exercises similar to those in the test battery were rarely performed, where, for example, one preschool administered ball exercises for 5-year-old preschoolers only in January and for 6-year-olds in September, or, in another preschool, only in October and then November, whereas in February the children practiced hanging from a ladder and in April ball throwing and climbing a gymnastics ladder. In another preschool, records showed that in a group of 6-year-olds only in February did they perform various related exercises climbing a gymnastics ladder and catching and throwing a ball. Discussion The aim of this study was to evaluate the motor skills of children in two age groups and those who had either already attended one year of preschool or had just begun their education at the beginning and end of the school year. This allowed for an assessment of what gains in their education were made, or what has also been termed as educational value added. Summarizing the motor skill levels of the analyzed 5- and 6-year-old children after performing exercises based on the physical education programs of their preschools, it appears that the children easily coped with exercises that were based on running and crawling. This was evidenced by the high results when running and jumping over an obstacle with one leg and crawling on an inclined gymnastics bench. On the other hand, tasks such as throwing, catching and bouncing a ball of the wall, and jumping rope were the least successfully completed by this group of children. In a study named Six-year-olds in Poland, Cieśla et al. found that children were able to throw a ball with both hands at a very high level [23]. Almost half of the analyzed children who were attending preschools obtained a grade of good in test-retest conditions. Similar results were obtained by children attending a primary school preschool program. Here, very good results were obtained by about 40% of the preschoolers in the first test and 37% in the retest. Only about 1% of the children could not perform the throwing task in both the test and retest. Similar results were obtained in a test measuring performance when catching a ball with both hands. The largest group children performed this task with good results (44% of children attending preschool in the first test and 44% in the retest; 43% of children attending a primary school preschool program in the first test and 46% in the retest). Only 3% of the children attending preschools or preschool programs were unable to complete the task in the first test; in the retest 5% of preschoolers and almost 5% of children attending preschool programs could not complete the task [23]. In the present study, the results of the test involving throwing a ball against a wall and catching had 20.4% of 6-year-olds unable to complete this task when tested at the beginning of the school year and slightly more, 23.6%, at the end of the school year. The difference between the results of Cieśla et al. [23] and the present study may stem from the fact that the motor tasks herein were more difficult to perform. They involved a combination of catching and throwing or throwing and catching movements and not standalone tasks. The weakest skills of the children were evidenced in jumproping. Only a handful of individuals were able to jump rope. Subjective reporting by the children who did jump rope revealed that they did not learn this skill in their preschool. This was confirmed by analysis of the preschools physical fitness logs, finding that none of the teachers administered any exercises with a jump rope, or in fact administered exercises that involved balanced walking on a balance bench, crawling, or running while jumping over low obstacles. This is regrettable, as it is naturally difficult for young children to acquire skills that are neither introduced nor developed in preschool. Brańska [24] stressed that education is the process of supporting (stimulating) the individual development of children and that its essence lies in the communication and mutual participation of both teacher and student in the educational process, where children learn from their teacher and the teacher learns from their children [and thereby the] quality of education is progressively dependent on the teacher, classroom conditions, and the curriculum [24, pg. 8]. Although following an educational program is not the only or most important condition for properly stimulating the individual development of a child, it can be helpful in the everyday life of teachers only if it provides suitable ideas that teachers would want and know how to implement. Conclusions The motor skill level of 5-year-old children beginning preschool was the highest in Test III, crawling on an inclined gymnastics bench, and Test IV, running and jumping over an obstacle with one leg. Five- and six-year-olds continuing preschool also performed the best in Test III, crawling on an inclined gymnastics bench, Test IV, running and jumping over an obstacle with one leg, but also in Test I, walking on a balance bench. All groups performed Tests III and IV with rela- 319

40 M. Rokicka-Hebel, Preschool attendance on motor skill development tive success, although 6-year-olds both beginning and continuing preschool showed a high motor skill level in Test I. In all four groups, the largest percentage of children that was unable to complete one of the tasks was in Test VI, throwing a ball against a wall and catching it, and Test VII, jumproping. It was noticed that, in Test VI, the motor skills of the children did not progress enough to perform this task even after a year of preschool. One of the reasons can be attributed to the children not realizing enough exercises and games played with a ball. Similarly, in effect none of the children showed the ability to jump rope (Test VII), which may result from the complete lack of this kind of exercise in preschools. The largest percentage of 5-year-olds beginning preschool who made a large error when performing the tasks was in Test V, catching and throwing a ball over an obstacle, and in Tests V and II (climbing a gymnastics ladder) by 6-year-olds. The group of 5-year-olds continuing preschool had the largest problem with performing Test II, climbing a gymnastics ladder, and Test V, catching and throwing a ball over an obstacle, while 6-year-olds continuing preschool only had problems with Test II. After completing a year of preschool, the 5-yearolds beginning preschool featured improved motor ability in Tests II, climbing a gymnastics ladder, IV, running and jumping over an obstacle with one leg, V, catching and throwing a ball over an obstacle, VI, throwing a ball against a wall and catching it, and VII, jumproping. In contrast, 6-year-olds beginning preschool improved only in Tests I, balanced walking on a balance bench, and IV, running and jumping over an obstacle with one leg. It is worth noting that the performance ability of the 6-year-olds beginning preschool in Test V, catching and throwing a ball over an obstacle, worsened after attending school for a year. After a year of school, the group of 5-year-olds continuing preschool improved their performance in Tests II, climbing a gymnastics ladder, IV, running and jumping over an obstacle with one leg, and VI, throwing a ball against a wall and catching it. Among the 6-year-olds continuing preschool, this group improved in Tests VI, throwing a ball against a wall and catching it, and VII, jumproping. Research also found that the teachers of the examined preschoolers did not follow the physical activity exercises included in their curriculum. The fact that some of the children appeared to show a regression of the skills tested in the study after a year of preschool should be assessed negatively. 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Minister of Public Works and Government Services Canada, Ottawa Corbin C.B., Pangrazi R.P., Physical activity for children: a statement of guidelines for children aged 5 12, 2 nd ed. National Association for Sport and Physical Education, Reston Baranowski T., Hooks P., Tsong Y., Cieslik C., Nader P.R., Aerobic physical activity among third- to sixth-grade children. J Dev Behav Pediatr, 1987, 8 (4), Trost S.G., Pate R.R., Sallis J.F., Freedson P.S., Taylor W.C., Dowda M., Sirard J., Age and gender differences in objectively measured physical activity in youth. Med Sci Sports Exerc, 2002, 34 (2), , doi: / Rowlands A.V., Pilgrim E.L., Eston R.G., Patterns of habitual activity across weekdays and weekend days in 9 11-year-old children. Prev Med, 2008,/46 (4), , doi: /j.ypmed Bailey R.C., Olson J., Pepper S.L., Porszasz J., Barstow T.J., Cooper D.M., The level and tempo of children s physical activities: an observational study. 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41 M. Rokicka-Hebel, Preschool attendance on motor skill development 18. Department of Health, At least five a week: Evidence on the impact of physical activity and its relationship to health. A report from the Chief Medical Officer., Department of Health, London 2004, Malina R.M., Anthropology and physical activity: a lifespan perspective [in Polish]. Medicina Sportiva, 2002, 6 (1), Sekita B., From studies on physical fitness of children aged Wroclaw years [in Polish]. Rozprawy Naukowe AWF we Wrocławiu, 1977, 13, Sekita B., Somatic development and physical fitness of children aged 3 7 years. Development efficiency and capacity of children and adolescents [in Polish]. AWF, Warszawa 1988, Ugodowska G., The level of physical fitness and movement children s nursery in Wroclaw [in Polish]. Kultura Fizyczna, 1992, 9 10, Cieśla E., Klimaszewska J., Kopik A., Markowska M., Szumilas M., Walasek B., Six-year-olds in Poland. Report 2006 [in Polish]. TEKST, Kielce Brańska E., What programs in pre-school education? [in Polish]. Wychowanie w przedszkolu, 2009, 8, 8. Paper received by the Editors: February 23, 2013 Paper accepted for publication, November 13, 2013 Correspondence address Magdalena Rokicka-Hebel ul. Bitwy pod Płowcami 60/ Sopot, Poland mrokickahebel@awf.gda.pl 321

42 2013, vol. 14 (4), An assessment of hydrodynamic and simulated race performance features of three C-1 hull designs doi: /humo Michael G. Robinson 1, Laurence E. Holt 1 *, Thomas W. Pelham 2 1 School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada 2 Waverley, Nova Scotia, Canada Abstract Purpose. Recently engineered Canadian Single (C-1) canoe hull designs have been found to produce less resistive drag than the traditional Delta design in tow tank test conditions. If these laboratory findings were found to be similar to on-water performance tests, then these new hull designs could give canoe sprint athletes a competitive advantage. However, these claims have not been independently confirmed nor has it been shown that these new designs result in improved performance under race conditions. Three C-1 hull designs (traditional Delta and the recently engineered Armageddon and Ergo-Starlight) were compared in order to detect differences in C-1 boat dynamics. Methods. The C-1 canoes were propelled by eleven national- and international-class paddlers who performed 350-m all-out trials from a dead start in each of the three crafts. One-way ANOVA compared differences in means for individual 50-meter segment and 350-meter performance times. Results. Performance times over the 350-meter race simulations were significantly faster (p = 0.038) among international-class paddlers with the Armageddon and Ergo-Starlight designs compared with the Delta. Conclusions. International level canoeists should expect improved performance times by choosing the Armageddon and Ergo-Starlight versus the Delta-designed C-1. Key words: canoe, hull design, paddling, sprint racing, technology Introduction In the sport of sprint canoe and kayak racing, performance improvements have been related to technological advancements [1, 2]. Until 1998, the Danish-made Delta design of the Canadian Single canoe (C-1, see Fig. 1, 2, 3) had dominated international sprint canoe competition. At the 1998 Sprint World Championships, the Polish-made Ergo-Starlight (Fig. 1, 2, 3) was introduced and within a year became the preferred C-1 design. In April of 1999, the Danish-made Armageddon (Fig. 1, 2, 3) was introduced to compete with the Ergo-Starlight. Although the Delta has been the preferred sprint race C-1 design for 30 years, it has been replaced by international level paddlers with the newer hull designs albeit little objective research showing improved craft performance. Over the past decade, there has been an architectural revolution in the field of sprint race canoe design. Tow tanks have been used to test, under various conditions, the factors affecting the motion and velocity of different sprint race canoe designs. These studies have found that the dimensions, shape, and material used in the construction of sprint race canoes can affect the motion and velocity of the craft. One of the most important factors is resistive drag force. Resistive drag is an opposing force, acting on the desired motions of the system (canoeist and craft). Two * Corresponding author. determinantal features of resistive drag force as related to any water-sport craft are the dimensions of the craft (e.g. shape) and the amount of surface area interface. Designers of the Armageddon (Struer Sprintboards, Denmark) and Ergo-Starlight (Plastex Composite, Poland) have made several design modifications to the basic Delta hull design in an effort to reduce resistive drag. The scientists, engineers, and naval architects of Struer and Plastex have attempted to decrease the amount of interface between the hulls of the crafts with the water (wetted surface) to reduce resistive drag force from a hydrodynamic standpoint. For example, one architectural change incorporated by the designers was a decreased surface area in the wing section of the Ergo- Starlight and Armageddon compared with the Delta (Fig. 1). In the Delta design, the large delta (diamond) shape (Fig. 2A, 3A) may add stability to the craft, but it also encompasses a large wetted surface area. However, the delta shape is reduced (less wetted area) in the Ergo- Starlight and Armageddon (Fig. 2A, 3A). The second important amendment relates to the bow sections of the Ergo-Starlight and Armageddon. When compared with the mid-section of the Delta (Fig. 2B, 3B), the streamlined mid-sections of the Ergo-Starlight and Armageddon allow for placement and tracking of the paddle parallel to the craft. This should allow for a more efficient application of force via the paddle during the propulsion phase of the canoe stroke. Furthermore, a streamlined mid-section may reduce the amount of resistive drag force as a consequence of less bow wave. This hydrodynamic-accommodating feature may be most 322

43 M.G. Robinson, L.E. Holt, T.W. Pelham, Three C-1 hull designs pronounced at higher race velocities. The line of travel of the craft is heavily influenced by the ordination of the placement of the paddle s blade and the direction of travel of the blade through the water during the propulsion phase of the canoe stroke. That is, at entry, if the blade is perpendicular to the water surface and travels in the opposite direction of the moving craft and parallel to the long axis of the craft, vector analysis theory would suggest that the canoeist is managing an efficient application of force. The application of force in a path not parallel to the long axis of the boat would lead to an insufficient expenditure of energy and fatigue, an obvious undesirable physiological consequence where the goal is to optimize performance. From a systems standpoint, the linear and parallel application of force via the blade will optimize the linear forward propulsion of the craft. Other design considerations include the breadth of the hull of the craft, consisting of the port and starboard wings. These wings are features of the craft designed to enhance stability. As such, the breath is the widest section of the hull and, from a hydrodynamic standpoint, a major factor in boat displacement. Indeed, the larger the displacement of the hull, the greater the interface between the boat surface and water and, consequently, increased resistance drag. In most cases, resistance drag has a negative effect on boat speed. Thus, streamlining the breadth should reduce resistance drag and therefore potentially improve boat speed. Although a wide breadth design may increase the stability of the craft particularly to counter wave action, Figure 4 illustrates that the wider breadth of the Delta requires the canoeist to place and manipulate the blade of the paddle in a direction not parallel to the long axis of the craft or through its center of mass. This generates torque on the system (a) Delta (b) Ergo-Starlight (c) Armageddon Figure 2A. Top view of the three C-1 designs: (a) Delta, (b) Ergo-Starlight, and (c) Armageddon; dashed outlines highlight the mid-sections of the craft (a) Delta (b) Ergo-Starlight Bow (a) Delta Port Wing Stern (c) Armageddon Figure 2B. Comparison of the mid-sections of the (a) Delta, (b) Ergo-Starlight, and (c) Armageddon; note that the Delta is wider compared with the Ergo-Starlight and Armageddon (b) Ergo-Starlight (c) Armageddon Figure 1. Port view of the (a) Delta, (b) Ergo-Starlight, and (c) Armageddon; box outlines highlight areas that correspond to wetted surfaces of the port wing section of the hulls; note the larger wetted area of the Delta compared with the Ergo-Starlight and Armageddon and creates a yawing moment, in what can be regarded as a hydrodynamically insufficient approach in boat locomotion. Another important factor is the construction material of the craft. During forceful propulsion, the hull shape of a craft constructed of delicate material can twist and bend, losing its potential hydrodynamic accommodating features. In the case of the Ergo-Starlight, the designers have used a reinforced honeycomb composite, which the manufacturer suggests is able to withstand torsion stress (changes in shape) during maximum race velocity. To the best knowledge of the authors, only after this evolution of design modifications has tow tank testing 323

44 M.G. Robinson, L.E. Holt, T.W. Pelham, Three C-1 hull designs (a) Delta (b) Ergo-Starlight (c) Armageddon Figure 3A. Rear view of the (a) Delta, (b) Ergo-Starlight and (c) Armageddon; curved lines highlight the breadth of the crafts (a) Delta (b) Ergo-Starlight (c) Armageddon Figure 3B. Comparison of the breadths of the Delta (a), Ergo-Starlight (b) and Armageddon (c) Note that the Delta (a) has a larger breadth compared to the Ergo-Starlight (b) and Armageddon (c) been used to compare the traditional Delta and the new Armageddon design. In this form of testing, the Armageddon was found to have 1.7% less surface resistive drag than the Delta at a velocity of 5 m/s [3]. However, these claims have not been independently confirmed, nor has it been shown that this new design will result in improved performance under race conditions. Ultimately, the only measure of technological advancement is reduced performance time. However, it would appear that paddling the Delta C-1 is not an efficient system in achieving better performance in sprint racing (Fig. 4). At the international level (e.g. Olympic Games, Word Championships), the venue for sprint canoeing is a marked 1000-m race course of nine straight parallel lanes. The goal for the canoeist is to paddle the race distance in the shortest time frame. Except for the 5000-m race, the canoeist is required to remain within their assigned lane and travel from the start to the finish line in one direction. To paddle a 200-m, 500-m, or 1000-m race, the canoeist attempts to travel in the shortest possible distance (straight line) from start to finish as it is the most energy efficient strategy of propelling the craft. Hypothetically, it appears that the energy expenditure of a canoeist racing in a Delta may be higher than that of a canoeist paddling an Armageddon or Ergo-Starlight. For example, a canoeist in the Delta may expend additional energy in manually steering the craft, and perform a greater number of strokes per distance, possibly with a great effort (force) per stroke. However, these interpretations have not been tested. Therefore, in order to determine if the recent changes in Olympic sprint C-1 canoe design indeed result in improved racing performance, the Ergo-Starlight and Armageddon along with the traditional Delta C-1 were tested and compared in simulated race conditions. D1 direction of Delta, L1 path of the blade of the paddle, 1 direction of force; D2 direction of Ergo-Starlight or Armageddon, L2 path of the blade of the paddle, 2 direction of force Figure 4. Diagrammatic representation of the paths of travel of the Delta, Ergo-Starlight, and Armageddon during propulsion via a canoe stroke Material and methods The experiment was based on a counterbalanced design where all participants performed trials in each of the three crafts. The order of trials was randomized to control for learning, fatigue, and environmental effects. The trials were then compared for differences in performance (time, dependent variable) based on treatment (C-1 design, independent variable). Of the twenty Canadian male national- and international-caliber C-1 paddlers asked to participate, eleven subjects completed the study. Participants competitive ability ranged from % of the best world championship performance time. Participants ranged in weight from 67.4 kilograms to 94.8 kilograms (77.53 ± 8.37 kilograms) and were 15 to 27 years of age (20.16 ± 4.87 years). Prior to taking part in this study, subjects were provided with a letter of information outlining the purpose and procedures of the study. Details of the study were made clear and any questions were addressed. They were then asked to sign a consent form. This study received ethical approval by the School of Health and Human Performance, Dalhousie University. The experimental procedure consisted of performing three blocks of trials during a 350-m all out race effort in the Delta, Ergo-Starlight and Armageddon crafts. 324

45 M.G. Robinson, L.E. Holt, T.W. Pelham, Three C-1 hull designs The distance of 350 m was chosen to minimize fatigue while being long enough to reflect the three stages (start acceleration, traveling speed, and finishing kick) of the 500-m and 1000-m race distances. This distance has been successfully used in previous experimental conditions [4]. Trials were performed individually from a dead start. All trials were performed on an internationally certified course located on a freshwater lake with markers present at 50-m intervals. Trials were randomized to control for the possible effect of fatigue and wind conditions. To minimize learning effects, participants paddled each of the crafts prior to taking part in the study for familiarization purposes. No testing was conducted until an adequate comfort level was established and confirmed by the participant. The weight of the each craft, including the floorboard and kneeling stand, was standardized to 16.4 kg. Each paddler selected a paddle to their liking and did not change paddles at any time in the study. Performance times were recorded and examined at 50-m intervals as well as the entire 350-m distance. Participants had a minimum of 20 min of rest between trials and were not made aware of the results until all trials were complete. Of the eleven subjects four completed three trial blocks, another four completed two trial blocks, and three completed one trial block. Therefore, all subjects performed at least one trial in each of the canoes. However, seven of the eleven subjects did not complete all three random sequences of trials. Several participants had training and competition obligations and were forced to drop out of the study. This reduced the sample size and therefore limited the statistical power of this study. Comparative analyses were performed for the performance times collected in the three canoe designs. Mean performance times were measured to determine differences among C-1 designs. A series of one-way analysis of variance (ANOVA) tests were carried out on all participants to compare differences in means for individual 50-m segments and 350-m performance times. Participants were then grouped based on 350-m performance times with the best paddlers (international) finishing below 100 seconds and slower (national) paddlers above 100 seconds. Arranged in this manner, ANOVA measures were again performed on the grouped data. Given that a difference between first and second place in international competition may be as small as 0.01 s, a p value of 0.1 was selected for the purpose of determining statistical significance. Results and discussion Mean performance times for the individual 50-m segments and overall 350-m distance are presented in Figu re 5 and Figure 6, respectively. It can be seen from Figure 6 that the Ergo-Starlight and Armageddon were faster than the traditional Delta in each 50-m segment, with the greatest difference in the middle 200 m stretch in favor Table 1. Statistical significance of ANOVA measures comparing mean 350-m performance times Grouping Craft Degrees of freedom p value All subjects Delta/ Ergo-Starlight/ Armageddon > 100 s Delta/ Ergo-Starlight/ Armageddon < 100 s Delta/ Ergo-Starlight/ Armageddon * < 100 s Delta/Ergo-Starlight * < 100 s Delta/Armageddon * < 100 s Ergo-Starlight/ Armageddon * p < 0.05 of the Ergo-Starlight. ANOVA of mean performance times found no statistical significance (p < 0.1) for the 350-m distance (Tab. 1) or for individual 50-m segments. Subjects were then grouped based on 350-m performance times with the best paddlers having a mean performance time below 100 s for all three crafts and the slower paddlers having a time above 100 seconds in one or more of the crafts. Grouped in this manner, ANOVA found statistical significance for the best paddlers in favor of the Ergo-Starlight and Armageddon C-1 designs (Tab. 1). One-way ANOVA tests used to compare the mean performance time of the best paddlers found significant differences for the third (p = 0.001) and the fourth (p < 0.078) 50-m segments (Tab. 2). Statistical significance (p = 0.038) was found among the best paddlers for the entire 350-m race simulation. Table 3 presents ANOVA results carried out on the Delta and Ergo-Starlight designs revealing significance in four of the seven 50-m segments as well as the overall 350-m distance. Although differences were found in mean performance times between the Ergo-Starlight and Armageddon designs (Fig. 5, 6; Tab. 1, 2), no statistically significant differences in performance time were found. However, for the 350-m trials, the Ergo-Starlight had a better mean performance time in most of the 50-m segments with the greatest difference found in the middle 200-m stretch (Fig. 5, 6; Tab. 1, 2). Given the fact that the World Championship sprint races are held over 200-, 500-, and 1000-m distances, it can be surmised that as race distance increases the positive effects of a more accommodating hydrodynamic craft may become more pronounced, resulting in statistically significant decreases in performance time. Limitations of the study that need to be taken into consideration include psychological bias, subject diversity, and performance variability. Performance variability may be partially explained by the time of the testing [5]. Testing was performed during the post-competitive sea- 325

46 M.G. Robinson, L.E. Holt, T.W. Pelham, Three C-1 hull designs 99, ,00 97, ) (s e 96,00 im T 90 95,00 Time (s) Time (s) Time (s) 15,00 14,50 14,00 13,50 Delta Ergo-Starlight Armageddon 94, ,00 93,00 Delta Ergo-Starlight Armageddon Figure 5. Means and standard deviations of 350-m performance times for all participants 12, m m m m m m m Figure 6. Mean 50-m Distance performance (m) (m) times for all participants Distance Table 2. ANOVA statistics of mean performance times of the best paddlers for individual 50-m and the overall 350-m segments n Delta Ergo-Starlight Armageddon Degrees Mean (s) SD (s) Mean (s) SD (s) Mean (s) SD (s) of freedom p value 1 st 50 m nd 50 m rd 50 m *** 4 th 50 m * 5 th 50 m th 50 m th 50 m m ** * p < 0.1, ** p < 0.05, *** p < 0.01 Distance n Table 3. ANOVA statistics comparing the Delta and the Ergo-Starlight Delta Ergo-Starlight Degrees Mean (s) SD (s) Mean (s) SD (s) of freedom p value 1 st 50 m ** 2 nd 50 m rd 50 m *** 4 th 50 m ** 5 th 50 m th 50 m * 7 th 50 m m ** * p < 0.1, ** p < 0.05, *** p < 0.01 son. Participants were in the recovery/transition phase of their seasonal periodization and were not in peak condition for sprint racing. Furthermore, Plagenhoef [6] stated that the best paddlers might not be pressed to commit all-out effort until the three-quarter mark during a race and only then if the race is closely contested. For this reason, this data may represent less than peak performance and must be cautiously interpreted. Validity of Tow Tank Testing Is the use of tank testing a valid means to measure craft performance as it relates to competition? In April of 1999, the Danish Marine Institute (DMI) performed tow tank testing to determine the hydrodynamic characteristics of the Delta and Armageddon C-1 designs, where Figure 7 displays the DMI s results for the crafts skin friction (surface drag) at velocities of 3 5 m/s. The hydrodynamic measures of kinetic resistance (drag) can be seen to overlay each other at speeds below 4.0 m/s with the Armageddon showing slightly less resistive drag force at speeds above 4.5 m/s. It was predicted by the DMI that at a speed of 5.0 m/s this would result in a 1.7% difference in time [3]. Indeed, more capable subjects performed significantly better in the Armageddon than in the Delta in the present study. 326

47 M.G. Robinson, L.E. Holt, T.W. Pelham, Three C-1 hull designs Resistance (Kp) Armageddon Delta 3 3 3,5 4 4,5 5 Velocity (m/s) Figure 7. Resistive drag for the Delta and the Armageddon designs from the Danish Marine Institute [3] (Kp kiloponds) Our results show a 3.07% difference in mean performance time between the two crafts in favor of the Armageddon. According to the DMI results there should be no significant difference due to resistive drag at speeds less than 5 m/s. However, it is important to note that boat velocity remained constant when drag resistance was measured during the DMI testing. True paddling consists of cyclic periods of accelerations, where peak velocities exceed those represented by the means recorded in this study. With this in mind, it would seem that the peak velocities of the best athletes exceeded the 4.0 m/s threshold, allowing them to take advantage of the craft s more accommodating hydrodynamic characteristics more so than the slower paddlers. Recommendations for further research Is the improved performance of the Armageddon and the Ergo-Starlight designs a result of decreased resistive drag or other design factors? The Armageddon is considerably narrower (streamlined) than the Delta and results in a paddle path both parallel and closer to the longitudinal axis of the craft. This and other design effects may be partially responsible for improved performance. A comparative biomechanical analysis of differences in the stroke mechanics of canoeists while racing in the Delta, Armageddon, and Ergo-Starlight would be a worthy investigation. It would be also be desirable to repeat tow tank testing similar to the DMI s on the Armageddon and the Ergo-Starlight to further determine the validity of such measures in predicting craft performance between these newly engineered C-1 hull designs. On-board accelerometers used by Pelham et al. [4] have been shown to be practical in the analysis of craft performance as related to paddle design. A collection of video, in-board accelerometer, and aerobic capacity data would provide for a more complete evaluation of craft performance. A study merging video and on-board accelerometry data is currently in progress by the senior author. Ultimately, competitive performance is the result of the interaction of the paddler and craft system. For this reason, future examinations of C-1 designs must involve performances at or near athletes peak condition and utilize international level paddlers over true race distances. In the future, without changes to the regulations determining craft design, athlete selection per boat will be increasingly based on anthropometric data and relevant climatic conditions of the racecourse. For example, individuals with smaller pelvic girths may be better suited for the number 1 position in the K-2 kayak or the number 1 and 2 positions in the K-4, whereas individuals with larger pelvic girths will be selected for positions closer to the stern of the craft. Similar conclusions may be reached for canoes, although athlete selection per position may differ, such as where smaller individual may be better suited to the limited space of the number 2 position of the C-2. Conclusions From a theoretical standpoint, including engineering (tow tank testing) and race simulations, the contemporary designs of the Armageddon and Ergo-Starlight have vastly more accommodating hydrodynamic features and advanced-material construction compared with the Delta. Canoeists racing in the Ergo- Starlight and Armageddon designs should feature improved performance times. References 1. Pelham T.W., Holt L.E., Stalker R.E., The etiology of paddler s shoulder. Aust J Sci Med Sport, 1995, 27, Toro A., Canoeing: An Olympic Sport. Olympian Graphics, San Francisco California Struer Sprintboats, Hydrodynamic Characteristics of the Delta and Armageddon. Struer Sprintboats, Denmark Pelham T.W., Holt L.E., Burke D.G., Carter A.G.W., Accelerometry for paddling and rowing. In: Hamill J., Derrick T.R., Elliott E.H. (eds.), Proceedings of the XI th International Symposium of the International Society of Biomechanics. Amherst Massachusetts June , Shapiro R., Kearney J.T., Methodological considerations for quantitative evaluation of paddling. In: Terauds J., Gowitzke B., Holt L. (eds.), Proceedings of the III and IV International Society of Biomechanics. Academic Press, Del Mar California 1987, Plagenhoef S., Biomechanical analysis of Olympic flatwater kayaking and canoeing. Res Q, 1979, 50, Paper received by the Editors: December 9, 2009 Paper accepted for publication: September 20, 2013 Correspondence address Laurence E. Holt School of Health and Human Performance Dalhousie University Halifax, Nova Scotia, Canada, B3H 3J5 larry.holt@dal.ca 327

48 2013, vol. 14 (4), Power production during bench press with different ranges of motion on stable and unstable surfaces doi: /humo Erika Zemková *, Michal Jeleň, Gábor Ollé, Tomáš Vilman, Dušan Hamar Comenius University, Bratislava, Slovakia Abstract Purpose. The study compared power during concentric-only and countermovement (CM) bench press with different ranges of motion (ROM) on a stable and unstable surface. Methods. A group of 22 fit men performed three repetitions of 1) full ROM concentric-only bench press, 2) full ROM CM bench press, 3) half ROM concentric-only bench press, and 4) half ROM CM bench press, on a bench (stable) and Swiss ball (unstable) at 60% 1RM. The FiTRO Dyne Premium system was used to monitor force and velocity and calculate power. Mean values of power during the acceleration and the entire concentric phases were analyzed. Results. No significant differences were found in mean power during concentric-only bench press on the bench and Swiss ball performed at half ROM and full ROM. Likewise, mean power during the concentric phase of half-range CM bench press on the bench and Swiss ball did not differ significantly. However, power values during full-range CM bench press were significantly higher on the bench than on Swiss ball. These differences were even more pronounced for mean power during the acceleration phase of full-range CM bench press on the bench compared with the Swiss ball. Contrary to this, these values did not differ significantly when the barbell was lifted during half ROM bench press on the bench and Swiss ball. Conclusions. Power was significantly lower during full-range CM bench press on the Swiss ball than on the bench, however, values did not differ significantly during stable and unstable half-range CM bench press. Key words: bench press, stable support base, Swiss ball, utilization of elastic energy Introduction * Corresponding author. Resistance exercises on unstable surfaces have recently grown in popularity. Though being suitable for rehabilitation purposes, their use in sports training remains a matter of debate. More pronounced activation of stabilizing muscles has been assumed as the main advantage of resistance exercises performed on unstable surfaces. This assumption was proven by electromyographic (EMG) studies showing significantly greater EMG activity of trunk-stabilizing muscles in unstable than stable conditions during exercises such as the curl-up [1], bridge [2, 3], dumbbell bench press [4], and squat [5, 6]. Intervention studies have also documented more effective improvements in trunk stability after short-term training programs using the Swiss ball compared with floor exercises [7, 8]. These findings indicate that instability resistance training may facilitate neural adaptation of the trunk-stabilizing muscles resulting in improved trunk stability. Alternatively, other studies have shown significantly lower peak isometric force in unstable conditions when compared with stable conditions during dumbbell bench press (60%) [9], isometric knee extension (70%), plantar flexion (30%) [10], and squat (46%) [6] and also the rate of force development during the squat (40.5%) [6]. However, when dynamic bench presses were performed on an unstable surface, the reductions were found to be smaller (approximately 6% in force and 10% in velocity and power outputs) [11]. Similar findings have been reported after resistance exercises performed as a mode of interval training on stable and unstable surfaces [12]. Here, in the initial set, mean power in the concentric phase of the lift decreased more intensely in unstable (Swiss ball) than in stable conditions both during bench press (13.2% and 7.7% decrease, respectively) and squat (10.3% and 7.2% decrease, respectively) exercises. In the final sixth set of eight repetitions, the rates of reduction of mean power in the concentric phase of the bench press were significantly greater in unstable than stable conditions (19.9% and 11.8%, respectively). On the other hand, there were no significant differences in the decline of power in the concentric phase of squat exercise performed on an unstable Bosu ball and a stable support base (11.4% and 9.6%, respectively). These findings [12] indicate that power outputs during resistance exercises are more compromised in unstable than in stable conditions and that this effect is more evident for the barbell bench press performed on a Swiss ball than for barbell squats on a Bosu ball. However, significant differences in mean power in the concentric phase of unstable compared with stable resistance exercises were only found when lifting heavier weights ( 60% 1RM) [13]. Video analysis showed that concentric muscle action did not occur immediately after the eccentric phase as participants had to stabilize their own body on the unstable support surface [13]. It 328

49 E. Zemková, M. Jeleň, G. Ollé, T. Vilman, D. Hamar, Power during stable and unstable bench press was hypothesized that most of the stored energy dissipates and is lost as heat and the stretch reflex fails to be activated. However, whether this effect is indeed due to the compromised ability to reuse elastic energy during countermovement (CM) resistance exercise on unstable surface needs to be proven. This effect was assumed to be evident only during CM resistance exercises performed throughout the full range of motion (ROM). Verification of this hypothesis was performed by comparing mean power during concentric-only and CM bench press with different ranges of motion on stable and unstable surfaces. Material and methods A group of 22 fit men (age 22.7 ± 2.7 years, height ± 7.8 cm, weight 79.0 ± 9.2 kg) volunteered to participate in the study. All had at least 4 years experience with resistance training although none had any experience with instability resistance training. All participants were informed about the procedures and main purpose of the study. They were asked to refrain from any strenuous exercises during the duration of the study. The study was performed in accordance with the ethical standards on human experimentation outlined in the Declaration of Helsinki. Participants underwent a familiarization session during which the test protocol was explained and trial resistance exercises were performed. Emphasis was placed on proper technique especially when performed on the unstable surface. The exercises were performed without and with countermovement using maximal effort during the concentric phase. For the experimental protocol, the participants randomly performed on different days one set of three repetitions of 1) full range of motion (ROM) concentric-only bench press, 2) full ROM countermovement bench press, 3) half ROM concentric-only bench press, and 4) half ROM countermovement bench press. Each set was performed once on the bench and once on a Swiss ball at 60% of 1 repetition maximum (1RM), which was calculated prior to the study for each participant in stable conditions. A rest interval of 2 min was provided between reps. The best result of the three repetitions for each exercise was selected for analysis. The CM bench press involved the participants lowering the barbell to the chest without making contact when transitioning from the eccentric to concentric phase. Any repetitions that made contact with the chest or failed to come within 0.05 m of the chest were disregarded and repeated after 1 min of rest. Bench press performed without CM started from an initial position on the chest (barbell positioned about 0.05 m from the chest). The participant then held the position for approximately 2 s before the tester gave the command that they were to perform the lift. Each participant was observed during the test to ensure that no countermovement was implemented. Real-time analysis allowed for the monitoring of all possible movement with the barbell. Participants were required to maintain the same grip width throughout the entire testing protocol. Emphasis was placed on maintaing contact between the hips and back with the bench. During unstable condition testing, the bench press was performed with the Swiss ball placed under the thoracic area and with both feet placed flat on the floor. For the half ROM bench press, boxes were placed on each side of the bench or Swiss ball limiting the range of motion to half of the entire movement (approx. 90º). The distance of the barbell movement was set up using a computer system described below. Each participant was observed during the test to ensure that the triceps did not touch the boxes. The distance of the barbell movement was controlled in graphic and digital form to be in the range of ± 5 cm. Only data which met the specified criteria were included for analysis. Basic biomechanical parameters during the tests were monitored using the FiTRO Dyne Premium system (FiTRONiC, Slovakia). The system consists of a precise analogue rotary sensor coupled to a reel. When pulling the tether, the reel is wound and a sensor measures velocity. Rewinding of the reel is guaranteed by string producing force of about 2 N. The signal is passed through a 12-bit analogue-to-digital convertor and sent to a PC by USB cable. Included comprehensive software was used to collect, calculate, and display real-time basic biomechanical parameters involved in exercise. The device was placed on the floor and attached to the barbell by a nylon tether (Fig. 1). Mean values of power during the entire concentric phase of lifting (P mean total ) and during the acceleration phase (P mean acc ) were selected for analysis. The system operates on Newton s law of universal gravitation (force equals mass multiplied by the gravitational constant) and the Newton s law of motion (force equals mass multiplied by acceleration). Instant force when moving the barbell in the vertical direction is calculated as a sum of gravitational force (mass multiplied by the gravitational constant) and acceleration force (mass multiplied by acceleration). Acceleration of the vertical movement (positive or negative) is obtained as a derivation of vertical velocity. Power is calculated as a product of force and velocity and the actual position by integration of velocity. Statistical analysis of the collected data was performed using SPSS ver for Windows (IBM, USA). The Kolmogorov Smirnov test for normality and Levenne s test for equality of error variances were performed on all variables, finding that the data were normally distributed and no significant differences in sample variance were detected. Statistical power was determined to be > 0.80 at the 0.05 alpha level. Data were then analyzed using a three-way analysis of variance (ANOVA) with repeated measures. Factors included surface type (stable, unstable) contraction type (concentric-only, 329

50 E. Zemková, M. Jeleň, G. Ollé, T. Vilman, D. Hamar, Power during stable and unstable bench press Figure 1. Measurement of strength parameters during full and half ROM bench press on the bench (above) and Swiss ball (below) using the FiTRO Dyne Premium system eccentric-concentric) range of motion (full, half). Where significant differences were detected at p 0.05, post hoc analysis was performed using Tukey s honest significance test. Descriptive statistics include means and standard deviations. Results The results are presented in Figures 2 and 3. No significant differences were found in mean power in concentric-only bench press on the bench and Swiss ball performed at half ROM (275.6 ± 28.7 W and ± 29.8 W, respectively) and full ROM (286.1 ± 30.2 W and ± 31.0 W, respectively). Likewise, mean power in the concentric phase of halfrange CM bench press on the bench and Swiss ball did not differ significantly (440.5 ± 39.8 W and ± 37.7 W, respectively). However, significant interactions were found for full-range CM bench press, F(1, 20) = 4.4, p = 0.028, where values of P mean total were significantly higher on the bench than on the Swiss ball (479.7 ± 44.7 W and ± 34.3 W, respectively). These differences were even more pronounced, F(1, 20) = 6.4, p = 0.008, for mean power during the acceleration phase of full-range CM bench press on the bench when compared to those on the Swiss ball (600.5 ± 58.1 W and ± 43.3 W, respectively). However, the values did not differ significantly when the barbell was lifted at half ROM on the bench and Swiss ball (558.0 ± 54.2 W and ± 49.1 W, respectively). Discussion It is known that concentric contraction using the stretch-shortening cycle (SSC) produces greater power output than a simple concentric contraction by itself [14 16]. An effective SSC requires three critical elements, including a well-timed preactivation of the muscle(s) before the eccentric phase, a short and fast eccentric phase, and an immediate transition (short delay) between the stretch (eccentric) and shortening (concentric) phase. The mechanisms underlying this enhancement of power are usually ascribed to the utilization of elastic energy stored in the elastic components of the muscles in combination with reflexively induced neural input [15, 17 20]. Alternative explanations propose that the prestretch of an active muscle alters the properties of the contractile machinery and that prior stretch allows the muscle to build up a maximum active state before the concentric contraction begins [21 23]. However, no differences were found in EMG activity between SSC and isometric condition in the concentric phase of a vertical jump, indicating that reflex activity was not involved in the observed increase of torque values [24]. These 330

51 E. Zemková, M. Jeleň, G. Ollé, T. Vilman, D. Hamar, Power during stable and unstable bench press Figure 2. Mean power in the concentric phase of half ROM bench press performed without and with countermovement (CM) on the bench and Swiss ball n.s. not significant Figure 3. Mean power in the concentric phase of full ROM bench press performed without and with countermovement on the bench and Swiss ball * p 0.05, ** p 0.01, n.s. not significant findings have led a number of scientists to suggest that reflex activity is not involved in increased force output during SSC [25]. It may be therefore assumed that the utilization of elastic energy can explain the enhancement of power during countermovement weight exercises. However, the ability to utilize elastic energy during resistance exercises may significantly differ when performed in stable vs. unstable conditions. This assumption may be corroborated by findings of significant differences in the physiological and biomechanical variables of stable and unstable resistance exercises. Marshall and Murphy [4] showed greater EMG activity of trunk-stabilizing muscles in unstable than in stable conditions during the dumbbell bench press. The high muscle activation during exercises performed on unstable surface can be attributed to their increased stabilization function. This is due to additional stresses imposed on the synergistic and stabilizing muscles of the trunk during bench press with the back supported by the unstable Swiss ball [26]. Preliminary analysis of the position of the barbell and its movement distance showed a sort of plateau between the eccentric and concentric phases of bench press performed on the Swiss ball. The duration of this phase depends on the stiffness of the ball as well as the weight lifted. On a less stiff ball or while lifting heavier weights, the participant is required to generate greater muscular effort to quickly change from the eccentric to concentric phase. On the other hand, when lifting lighter weights, the participant can utilize the elastic properties of the ball to accelerate the upward movement. The magnitude is proportional to the applied force (or weight lifted) and the induced deformation in the ball. Though it is possible to estimate the extent to which the ball is depressed by knowing the weight of the participant and barbell weights, the tangible stiffness of the ball is unknown and may vary across its surface. Therefore, the use of video analysis instead of calculating the force exerted by the ball may be more appropriate in this context. As shown in the present study, there were no significant differences in mean power in the concentric phase of full- and half-range bench press initiated from a static position on stable and unstable surfaces. Similarly, these values did not differ significantly during half-range CM bench press performed on the bench and Swiss ball. During such exercise, with a considerably lower contribution of elastic energy, it is likely that other factors such as greater muscle tension during unstable surface exercise contributed to similar production of power as in stable conditions. However, during full-range CM bench press on the Swiss ball, a presumably lower amount of energy was accumulated in the involved elastic tissues of muscles and tendons that could consequently be utilized for subsequent concentric contraction. This is mainly due to the delayed and prolonged amortization phase of the stretch-shortening cycle. The reasoning is that maximal force is produced around the turning point when the eccentric phase changes into the concentric phase. At the same time, the torso must be stabilized on the unstable surface in order to provide firm support for the contracting muscles. This additional task may compromise the contraction of the muscles acting on the barbell. Their less intensive contraction not only prolongs the change of movement direction, but because of lower peak force, negatively impairs accumulation of elastic energy. Consequently, this leads to lower power output in the concentric phase of full-range CM bench press on unstable than on stable surfaces. Indeed, significantly lower peak force values around the transition point from the eccentric to the concen- 331

52 E. Zemková, M. Jeleň, G. Ollé, T. Vilman, D. Hamar, Power during stable and unstable bench press tric phase weere found in unstable than stable bench press [27], although only at 80% and 60% 1RM but not at 40% 1RM. Because of lower force production during instability resistance exercises, some authors [4, 6] have recommended performing resistance exercises on stable surfaces in order to improve muscular strength and athletic performance. The main reasoning is that 80% of the maximum muscular strength required for its enhancement in trained individuals [28] is not met during instability resistance exercises. Taken altogether, lower peak force in the transition point from the eccentric to the concentric phase and the delayed and prolonged amortization phase of the stretch-shortening cycle are most likely responsible for lower power production in the acceleration and entire concentric phase of lifting. Conclusions There were no significant differences in mean power of concentric-only bench press on the bench and Swiss ball performed at half ROM and full ROM. Likewise, mean power in the concentric phase of half-range CM bench press on the bench and Swiss ball did not differ significantly. However, power during full-range CM bench press was significantly higher on the bench than on the Swiss ball. These differences were even more pronounced in mean power produced during the acceleration phase of full-range CM bench press on the bench than on the Swiss ball. Contrary to this, these values did not differ significantly when the barbell was lifted during half ROM bench press on the bench and Swiss ball. Taking into account that no significant differences in power output during half-range CM bench press on the bench and Swiss ball were found and that significantly lower values were recorded during full-range CM bench press on the Swiss ball than on the bench, it is likely that unstable conditions compromise the ability to utilize elastic energy stored during the eccentric phase of lifting. These findings need to be taken into account when instability resistance exercises are implemented into a training program especially for sports requiring maximal force production in a short amount of time. Future research should be directed toward intervention studies evaluating the effects of instability resistance training on explosive strength and other related variables of athletic performance. Acknowledgments This project was supported through by the Scientific Grant Agency of the Ministry of Education of Slovak Republic and the Slovak Academy of Sciences (No. 1/0070/11). References 1. 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J Strength Cond Res, 2008, 22 (5), , doi: /JSC.0b013e31817b03a Zemková E., Jeleň M., Kováčiková Z., Ollé G., Vilman T., Hamar D., Power outputs in concentric phase of resistance exercises performed in the interval mode on stable and unstable surfaces. J Strength Cond Res, 2012, 26 (12), , doi: /JSC.0b013e31824bc Zemková E., Hamar D., Utilization of elastic energy during weight exercises differs under stable and unstable conditions. J Sports Med Phys Fitness, 2013, 53 (2), Norman R.W., Komi P.V., Electromechanical delay in skeletal muscle under normal movement conditions. Acta Physiol Scand, 1979, 106 (3), , doi: /j tb06394.x. 15. Komi P.V., Physiological and biomechanical correlates of muscle function: effects of muscle structure and stretchshortening cycle on force and speed. Exerc Sport Sci Rev, 1984, 12, Wilson G.J., Murphy A.J., Pryor J.F., Musculotendinous stiffness: its relationship to eccentric, isometric, and concentric performance. 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53 E. Zemková, M. Jeleň, G. Ollé, T. Vilman, D. Hamar, Power during stable and unstable bench press 19. Komi P.V., Bosco C., Utilization of stored elastic energy in leg extensor muscles by men and women. Med Sci Sports Exerc, 1978, 10 (4), Bosco C., Viitasalo J.T., Komi P.V., Luhtanen P., Combined effect of elastic energy and myoelectrical potentiation during stretch-shortening cycle exercise. Acta Physiol Scand, 1982, 114 (4), , doi: /j tb07024.x. 21. Bosco C., Viitasalo J.T., Potentiation of myoelectrical activity of human muscles in vertical jumps. Electromyogr Clin Neurophysiol, 1982, 22 (7), Avis F.J., Toussaint H.M., Huijing P.A., van Ingen Schenau G.J., Positive work as a function of eccentric load in maximal leg extension movements. Eur J Appl Physiol, 1986, 55 (5), , doi: /BF Bobbert M., Gerritsen K., Litjens M., van Soest A., Why is countermovement jump height greater than squat jump height? Med Sci Sports Exerc, 1996, 28 (11), Finni T., Ikegawa S., Lepola V., Komi P., In vivo behavior of vastus lateralis muscle during dynamic performances. Eur J Sport Sci, 2001, 1 (1), 1 13, doi: / van Ingen Schenau G.J., Bobbert M.F., de Haan A., Does elastic energy enhance work and efficiency in the stretchshortening cycle? J Appl Biomech, 1997, 13 (4), Behm D.G., Anderson K.G., The role of instability with resistance training. J Strength Cond Res, 2006, 20 (3), , doi: /R Zemková E., Hamar D., Maximal force and power in concentric phase of chest presses on stable and unstable surface at different weights lifted. XXXII World Congress of Sports Medicine. FIMS, Rome 2012, Kraemer W.J., Adams K., Cafarelli E., Dudley G.A., Dooly C., Feigenbaum M.S. et al., American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports Exerc, 2002, 34 (2), Paper received by the Editors: July 31, 2013 Paper accepted for publication: November 5, 2013 Correspondence address Erika Zemková Faculty of Physical Education and Sports Comenius University Nábr. arm. gen. L. Svobodu Bratislava, Slovakia zemkova@yahoo.com 333

54 2013, vol. 14 (4), The influence of different Cardan sequences on three-dimensional cycling kinematics doi: /humo Jonathan Sinclair 1 *, Jack Hebron 1, Howard Hurst 1, Paul Taylor 2 1 Division of Sport Exercise and Nutritional Sciences, University of Central Lancashire, United Kingdom 2 School of Psychology, University of Central Lancashire, United Kingdom Abstract Purpose. Three-dimensional (3-D) kinematics are widely utilized to quantify movement in cycling analyses. Three-dimensional angular kinematics are obtained using the Euler/Cardan technique, however, Cardan angles are influenced by their ordered sequence and may affect the resultant angular parameters. An XYZ sequence of rotations is currently recommended, although this technique may not always be appropriate when coronal and transverse plane angles are quantified. This study aimed to determine the influence of the six available Cardan sequences on 3-D lower extremity kinematics during cycling. Methods. Kinematic information was obtained from twelve cyclists using an optoelectronic 3-D motion capture system operating at 250 Hz. Repeated measures ANOVAs were used to compare the kinematic parameters obtained using the six Cardan sequences, and intraclass correlations were employed to detect the presence of crosstalk across planes. Results. The results show that discrete kinematic parameters in the sagittal, coronal and transverse planes were significantly greater when using the YXZ and ZXY sequences. It was also observed that these sequences were associated with the strongest correlations from the sagittal plane and also exhibited evidence of gimbal lock. Conclusions. The results suggest that the accurate representation of 3-D kinematics during cycling should continue utilizing the XYZ sequence and avoid the use of the YXZ and ZXY sequences. Key words: biomechanics, motion capture, Euler angles Introduction The use of three-dimensional (3-D) segmental kinematics is now widely utilized in cycling analyses [1]. Typically, 3-D angular kinematics are obtained using the Euler technique in which the position and orientation of a rigid segment axis is computed with respect to another [2]. When calculating a joint angle using the Euler method, there are two separate coordinate systems. In the case of a joint angle, each coordinate system belongs to a body segment as two adjoining segments represent a joint (e.g. shank relative to thigh represents a knee angle). One segment is delineated as the reference and the other segment moves relative to the reference segment allowing joint angles to be quantified. The quantification of Euler angles is achieved using an ordered sequence of rotations [2, 3]. An XYZ sequence of rotations in which X denotes sagittal plane, Y coronal plane and Z transverse plane motion is currently the most widely utilized and advocated sequence of rotations in 3-D kinematic analyses [4, 5]. This recommendation was developed around the notion that the first rotation be the one with the greatest angular displacement. Despite this recommendation, the dominance of sagittal plane rotations during most movements means that the first rotation * Corresponding author. can influence the coronal and transverse plane waveforms in a process known as crosstalk [5]. The lower extremity joints play a key role in the pedal stroke during cycling. The hip, knee and ankle rotations facilitate locomotion and transmit forces and rotational energy to the pedals [1]. However, between 42% and 65% of recreational cyclists may experience an overuse injury to the lower extremities as a result of cycling training [1]. The tri-planar nature of the pedal stroke has been linked to motions that may lead to maladaptive joint loading [6]. Therefore, given the potential clinical implications of the movement and its importance to the generation of rotational movement of the cranks, the correct interpretation of the movement is essential for future kinematics analyses. A small number of analyses have inspected the effect of altering the Euler sequence of rotations on the resultant 3-D kinematic parameters [2, 3]. Schache et al. [2] investigated the influence of different Cardan sequences on lumbo-pelvic complex kinematics during running. They showed that differences between each of the Cardan angle sequences did not exceed 7.0 and 2.8 for the lumbar spine and pelvic motions, respectively. It was concluded that different Cardan angle sequences did not substantially affect 3-D lumbo-pelvic angular kinematic patterns during running. Sinclair et al. [3] examined the effects of altering the sequence of rotations on 3-D ankle joint kinematics during running. Their results showed that, in the transverse and coronal planes, peak angle and range of motion values using the 334

55 J. Sinclair, J. Hebron, H. Hurst, P. Taylor, Influence of Cardan sequences YXZ and ZXY sequences were significantly greater than other sequences. Furthermore, utilization of YXZ and ZXY sequences was associated with the highest levels of planar crosstalk from the sagittal plane. However, these analyses examined the influence of altering the sequence of rotations in movements in which there is a relatively small amount of sagittal plane range of movement, and thus the potential for planar crosstalk from this plane was reduced. Therefore, the most efficacious technique for the quantification of 3-D kinematics during movements such as cycling in which sagittal plane motion strongly predominates is not yet known. As such, the aim of this study was to examine the influence of the six available Cardan sequences on 3-D hip, knee and ankle joint kinematic parameters and planar crosstalk during the pedal cycle. Material and methods Twelve male participants volunteered to take part in this investigation. All were free from musculoskeletal pathology at the time of data collection. The mean charac teristics of the participants were: age ± 3.53 years, height 1.75 ± 0.09 m and body mass ± 7.25 kg. Ethical approval for this project was obtained from the University of Central Lancashire s School of Sport Tourism and Outdoors ethical committee. All data collection was completed using a cycle ergometer (Ergomedic 874E, Monark Exercise, Sweden). Participants were required to cycle at a constant workload of 170 W, where a 2 kg load was placed in the ergometer s weight basket requiring them to maintain a cadence of 80 RPM throughout data collection. Saddle height was quantified using the LeMond [7] formula. Participants rode without cleats on flat pedals to mini mize the effect of riding using unfamiliar pedal configurations. Kinematic data were obtained using an eight camera optoelectronic motion capture system (Qualisys Medical AB, Sweden) using a capture frequency of 250 Hz. The calibrated anatomical systems technique [8] was used to quantify segmental kinematics. To delineate the anatomical frames of the right foot, shank and thigh, retroreflective markers were positioned unilaterally to the calcaneus, 1 st and 5 th metatarsal heads, medial and lateral malleoli, medial and lateral epicondyle of the femur, and greater trochanter. To describe the pelvic co-ordinate axes, additional markers were placed on the anterior (ASIS) and posterior (PSIS) superior iliac spines. Tracking clusters were also positioned on the shank and thigh segments. A static calibration trial was conducted during which the participant stood in the anatomical position in order for the positions of the anatomical markers to be referenced in relation to the tracking clusters (Fig. 1). Data processing involved time normalization of the obtained kinematic curves to 100% of the pedal cycle. Movement trials were digitized using the included Qualisys Track Manager software and exported as C3D files. Figure 1. Pelvic, thigh, shank and foot segments, with segment co-ordinate system axes (P XYZ pelvis, SH XYZ shank; TH XYZ thigh, FT XYZ foot ) Kinematic parameters were quantified using Visual 3-D (C-Motion, USA) after marker data were smoothed using a low-pass Butterworth 4 th order zero-lag filter at a cutoff frequency of 15Hz [9]. Three-dimensional kinematics of the hip, knee and ankle joints were calculated using XYZ, XZY, YXZ, YZX, ZXY and ZYX Cardan sequences referenced to co-ordinate systems about the proximal segment in accordance with previous recommendations [5]. The designations for rotations were: X sagittal, Y coronal and Z transverse plane rotations. Discrete parameters of 1) peak angle during the pedal cycle, which could be either a maximum or minimum value, and 2) relative range of motion (ROM) from top dead centre-peak angle were extracted from each Cardan sequence from the full pedal cycle. All discrete variables used for statistical analysis were specific to each Cardan sequence. Descriptive statistics including means and standard deviations were calculated for each Cardan sequence. Differences in these parameters as a function of the different Cardan sequences were examined using oneway repeated measures ANOVAs with a Bonferroni adjusted alpha criterion (p 0.003) to control for type I error. Post-hoc pairwise comparisons also using a Bonferroni adjustment were utilized to examine significant main effects. Effect sizes were calculated using partial eta squared ( 2 ). Intra-class correlations (ICC) were utilized to compare between sagittal, coronal and transverse plane waveforms using the six different Cardan sequen ces. 335