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

3 2013, vol. 14 (2) contents physical activity, fitness and health Anna Burdukiewicz, Jan Chmura, Jadwiga Pietraszewska, Justyna Andrzejewska, Aleksandra Stachoń, Jarosław Nosal Characteristics of body tissue composition and functional traits in junior football players...96 Anna Zwierzchowska Gender-based dimorphism of aerobic and anaerobic capacity and physical activity preferences in deaf children and adolescents applied sport sciences Mauro Gonçalves, Anderson Souza Castelo Oliveira Effects of elbow flexor muscle resistance training on strength, endurance and perceived exertion Beata Makaruk, Henryk Sozański, Hubert Makaruk, Tomasz Sacewicz The effects of resisted sprint training on speed performance in women Tomasz Tasiemski, Joanna Bauerfeind Subjective assessment of sports success in wheelchair rugby proposal of a new research tool Piotr Kuczek On the possibility of applying achievement goal theory in competitive sports biomechanics and motor control Emmanuel S. da Rocha, Álvaro S. Machado, Pedro S. Franco, Eliane C. Guadagnin, Felipe P. Carpes Gait asymmetry during dual-task obstacle crossing in the young and elderly Dalwinder Singh, Sukhwinder Singh Effects of vertical and horizontal plyometric exercises on running speed Tomasz Niznikowski, Jerzy Sadowski, Andrzej Mastalerz The effectiveness of different types of verbal feedback on learning complex movement tasks physiological aspects of sports Marek Zatoń, Dariusz Dąbrowski Differences in the direction of effort adaptation between mountain bikers and road cyclists Krzysztof Durkalec-Michalski, Małgorzata Woźniewicz, Joanna Bajerska, Jan Jeszka Comparison of accuracy of various non-calorimetric methods measuring energy expenditure at different intensities psychological diagnostics of sport and exercise Monika Guszkowska, Katarzyna Sempolska, Agnieszka Zaremba, Marta Langwald Exercise or relaxation? Which is more effective in improving the emotional state of pregnant women? Linda Schücker, Norbert Hagemann, Bernd Strauss Analogy vs. technical learning in a golf putting task: an analysis of performance outcomes and attentional processes under pressure Publishing guidelines Regulamin publikowania prac

4 2013, vol. 14 (2), Characteristics of body tissue composition and functional traits in junior football players doi: /humo Anna Burdukiewicz *, Jan Chmura, Jadwiga Pietraszewska, Justyna Andrzejewska, Aleksandra Stachoń, Jarosław Nosal University School of Physical Education, Wrocław, Poland Abstract Purpose. The aim of this study was to examine the body tissue composition and functional traits of young football players. Methods. Analysis was performed on 23 junior football players. Body mass and height were measured. Bioelectrical impedance was used to assess the players body composition (fat mass, muscle mass, body cell mass and extracellular mass). The body mass index, body cell mass index and the extracellular mass/body cell mass ratio were also calculated. Functional traits were assessed by a one-on-one football game in an enclosed space with the objective to score the highest number of goals in a timed setting. Measurements of HRrest, HRmax and heart rate reserve were used to evaluate the efficiency of the subjects cardiovascular systems. Results. Insignificant differences in body tissue composition and cardiovascular efficiency were found regardless of what position was played. Overall, forwards were characterised by having the greatest height, the highest level of active body tissue development and the most efficient cardiovascular systems. Defenders were characterised by having larger body build, while midfielders displayed a significantly greater percentage of extracellular mass and EMC in relation to BCM. Conclusions. The results reveal that trends exist in the body tissue composition and cardiovascular efficiency of football players depending on which position they play. These differences reflect the varied physical efforts players perform during a match and should be taken into consideration when designing training programmes. Key words: body composition, heart rate, football Introduction The game of football requires players to perform periodically under high intensity by using aerobic energy sources that sometimes involves overloading the neuromuscular and hormonal systems. The ability of the neuromuscular system to produce maximum power in the lower extremities is particularly important for football players, since the ability to produce explosive efforts at maximum power and force together with a high contraction velocity seems to be one of the main physiological features which differentiate players at different training levels [1, 2]. On the other hand, the variation of sprint activity among football players is reflected in the variety of physiological responses players bodies produce. Results have shown that high intensity aerobic interval training leads to an increase in VO 2max without negative interference effects on strength, jumping ability or sprint performance [3]. One of the most informative and easiest to examine parameters is heart rate, which characterises the efficiency of the cardiovascular system [4]. Research has shown that whole-day heart rate monitoring is an objective, unobtrusive method for measuring physical activity at the age of puberty. For athletes in training, these data are commonly collected from the monitoring * Corresponding author. of heart rate changes and used to prevent the occurrence of fatigue [5]. It is commonly known that athletes performing to a high degree are characterised by an improved lowering of their resting heart rate (HR rest ). Furthermore, the correlations observed between maximum heart rate (HR max ), reflected as the highest heart rate achieved during exercise, and HR rest have been used to create an index that can compute VO 2max [6]. This research revealed that the absolute and relative values of maximum heart rate and oxygen absorption were higher in young elite players in comparison to their peers at a lower training level [7]. In amateur football, the recording of HR was confirmed to be useful for training purposes and was also applied to characterise metabolic expenditure during physical effort [8]. Furthermore, with regard to young players, the influence of puberty on body height and functional capacity have also been well substantiated. Children and youth performing sports, in comparison to their nonexercising peers, displayed greater development of their somatic features, body efficiency and physical fitness [9]. Studies performed on pubertal youths indicate that the level of biological maturity influences the variation of development regarding physical efficiency, velocity and strength. The period of greatest body growth is frequently followed by a significant rise in static and explosive force development. Analogous changes in VO 2max have been found to accompany the pubertal spurt of body height [10]. The application of multiple linear regres- 96

5 A. Burdukiewicz et al., Body composition and functional traits sion analysis revealed the existence of a significant relationship between maturity advancement, growth and composite football skill scores in a group of football players at the age of puberty [11]. Positive regression coefficients were obtained for the occurrence of puberty and aerobic resistance. However, the coefficient for body height was negative, indicating the role of a lower centre of gravity in better football skill performance. However, Philippaerts et al. [12] observed that the period during the greatest height spurt coincides with the development of maximum balance ability, explosive force, running speed, upper-body muscular endurance, agility, cardiorespiratory endurance and anaerobic capacity. A plateauing of explosive force development, upper-body muscular endurance and running speed was observed after the pubertal height spurt, at which point body flexibility increasingly developed. Body tissue composition constitutes one of the factors that not only determine athletes motor fitness and sport level but also plays a role in training. Moreover, it varies tremendously across individuals in regards to age and body build. In this regard, adolescence is a very important phase in life due to various social factors that adolescents face and the numerous neuro-hormonally determined changes that affect body tissue composition. This includes the influence of growth hormone, which has, among others, been found to be of significant importance in the maturation of lean mass and muscle strength development at puberty and for young adults in general [13]. The results of research also indicate that a relationship exists between fat (determined by anthropometric measurement) and the beginning of puberty in both genders. In the case of young football players, development of choice body tissue components (lean tissue) has been noted as the result of improved physical performance [14, 15]. The development of adolescent boys is, in particular, characterised by an overall decrease in fat tissue and increase in BMI, which at this age reflects an increase in lean mass [16]. Youth involvement in sport (e.g. football) has also been credited in stimulating bone mass development. However, longitudinal research on a cadet football league (youths aged 11 14) did not reveal any acceleration in their morphological development, although it was revealed that muscle power, especially agility and coordination, distinguished the young football players from their untrained peers [17]. Therefore, in order further to investigate this issue, this study examined the features of body tissue composition and functional traits of a group of young 2 nd league football players. Material and methods Twenty-three junior football players playing on a 2 nd league team from Wrocław, Poland were recruited. The players mean age was 16.2 years ( ± 0.70) and had mean training period of 7.3 years (± 1.87). The university s research ethics committee approved the study and all participants provided their written informed consent prior to data collection, which took place at the end of the 2009 competitive season. Information regarding what position they played in was obtained from their coach. Body mass and height were measured and used to calculate body mass index (BMI; body mass [kg]/body height [m] 2 ). Body composition was assessed by bioelectrical impendance with a BIA-101/S analyser (tetrapolar version, electrodes placed on the hand foot) integrated with Bodyimage 1.31 software (Akern, Italy). Body composition was measured before an exercise test, with fat mass (FM), muscle mass (MM), body cell mass (BCM) and extracellular mass (ECM) recorded. The components of body composition were expressed in kilograms or percentage of body mass. Body composition measurements were used to compute the body cell mass index (BCMI = BCM [kg] / body height [m] 2 ) and the ratio of ECM/BCM (extracellular mass/body cell mass). The players functional abilities were measured in special test conditions in order to promote high-intensity exercise: individual players participated in a threeminute game of one-on-one football within an enclosed, circular cage (a diameter of 500 cm with 250 cm walls) with goals located on both sides (Hattrick Cage, Ludus Partner, Poland). The aim of the game was to score the highest number of goals. Resting heart rate (HR rest ) was measured prior to the test, while maximum heart rate (HR max ) was measured immediately after each game. Heart rate was monitored and analysed with a shortrange telemetry system (Polar Electro Oy, Finland). Heart rate reserve (HRR) was computed by subtracting HR rest from HR max. Statistica version 9.0 for Windows (StatSoft Inc., USA) was used for statistical analysis. Basic statistical characteristics were computed (mean, standard deviation). The Shapiro-Wilk s test was used to evaluate normal distribution. One-way between-groups analysis of variance (ANOVA) with Tukey s post hoc test was used to evaluate the variation of the values recorded for body tissue composition and the physiological features among the participants depending on their position (forwards n = 7, midfielders n = 9, defenders n = 7). Statistical significance was set at p Results The anthropometric characteristics and functional abilities of the football players are presented in Table 1. The Shapiro-Wilk s test indicates that body height and mass and the studied components of body composition and the players physiological response present normal distribution. Analysis of variance, applied to evaluate the variation of the analysed features between those playing as forwards, midfielders and defenders, did not reveal any statistically significant differences (Tab. 2) except 97

6 A. Burdukiewicz et al., Body composition and functional traits for the percentage of extracellular mass between forwards and midfielders. The results find that forwards are characterised by the highest body height, body cell mass, muscle mass and fat mass. HR max and HRR values were also at a high level. Furthermore, forwards displayed the lowest levels of extracellular mass development, ECM/BCM and resting heart rate. Furthermore, the BMI and BCMI indices indicate that forwards had the largest body build as well as exhibiting the highest HR max. When compared Table 1. Physical characteristics of the junior football players (N = 23) Variable Mean SD Body mass (kg) Body height (cm) Fat mass (kg) Body cell mass (kg) Extracellular mass (kg) Muscle mass (kg) Fat mass (%) Body cell mass (%) Extracellular mass (%) Muscle mass (%) BMI (kg m 2 ) BCMI (kg m 2 ) ECM/BCM HR rest (b min 1 ) HR max (b min 1 ) HRR (b min 1 ) with the other positions, their BCM percentage, muscle mass and heart rate reserve were at lower levels. Overall, midfielders displayed the smallest body size. This group also exhibited the lowest level of body fat and BMI and BCMI values. Their HR max values were the lowest compared with the other positions. However, when compared with forwards and defenders, midfielders were characterised by a significantly greater amount of extracellular body mass and larger values of the ECM/ BCM index. Discussion The specificity of modern sport necessitates taking into consideration certain body build predispositions in order to determine what somatic criteria ought to be used when selecting potential athletes in given sport. The optimum adaptation of an athlete to the requirements of the sport they play in is in large part the result of their morphological structure and a targeted training regimen that modifies selected somatic parameters. For young athletes, in addition to the above factors, puberty also plays a large role in promoting significant changes in body morphology and tissue composition [18]. This period is characterised by an increase in height, mass, lean mass and bone mineral content. When compared with girls, the fat content of boys is at a lower level, where this predisposition is also reinforced by the large-scale involvement of young boys in sport. Although the physical load youths undergo depends on the sport, most training is sufficient enough to cause characteristic changes in the development level of various body com- Table 2. Physical characteristics of the junior football players grouped by playing position (mean ± SD) Playing position Variable Forwards (n = 7) Midfielders (n = 9) Defenders (n = 7) p Body mass (kg) ± ± ± Body height (cm) ± ± ± Fat mass (kg) ± ± ± Body cell mass (kg) ± ± ± Extracellular mass (kg) ± ± ± Muscle mass (kg) ± ± ± Fat mass (%) ± ± ± Body cell mass (%) ± ± ± Extracellular mass (%) ± 2.16* ± ± Muscle mass (%) ± ± ± BMI (kg m 2 ) ± ± ± BCMI (kg m 2 ) ± ± ± ECM/BCM 0.67 ± ± ± HR rest (b min 1 ) ± ± ± HR max (b min 1 ) ± ± ± HRR (b min 1 ) ± ± ± * significantly different from midfielders (p < 0.05) 98

7 A. Burdukiewicz et al., Body composition and functional traits position and functional features. For example, a study of young prepubertal football players revealed a decrease in body fat and an increase in lean body and bone mineral content in comparison with their control group peers [19]. A significant increase in bone mineral content around the femur neck and lumbar spine areas was also observed in male adults practicing recreational football for many years [20]. When comparing playing positions, body composition analysis on adult football players found observable differences between goalkeepers and outfield players [21]. Regarding youth, all players aside from goalkeepers revealed little difference in the development of their body composition. The results indicate that the lowest amount of fat tissue is observed in midfielders, although similar values were noted for forwards and defenders. However, greater variation of fat tissue levels has been revealed in adult players [22]. Significantly greater fat mass was discernible in midfielders in comparison with forwards and defenders. Lean body mass consists of body cell mass, extracellular fluid and extracellular solids [23]. Body cell mass, which is the mass of all metabolically active body cell components, plays a significant role in physical training. Chronic diseases such as AIDS, tumours or cancers and the ageing process all result in a decrease of BCM. The metabolic activity of BCM and its significant role in the human body is also evident in how diversified its development is, although depending on the physical activity an individual performs and their training level [24]. The results confirm previous studies that have indicated an insignificant variation in the somatic structure and body composition of outfield players in relation to players in other positions [25]. The largest BCM and muscle mass values are observed in forwards while the lowest in defenders. Melchiorri et al. [26] observed a similar trend by analysing the body composition of two professional male football teams from two different divisions. The higher ranked team displayed significantly lower levels of body fat in its defenders, while higher BCM values were noted among the forwards from both teams. Players who were individually ranked higher displayed greater cell mass, even though the two teams differed in age, body mass, height and BMI. The players analysed in this study did not display significant differences in body mass and tissue composition. Previous research has confirmed a correlation between athletes BMI and creatinine concentration although this is dependent on the practiced sport, type of training, involvement of aerobic and anaerobic metabolism and the length of the competitive season [27]. Nevertheless, other research on athletes of both genders and people with eating disorders indicated that body cell mass index, in comparison to BMI, is better suited to monitor changes in the amount of muscle mass [28]. This results from the fact that the body cell mass index is more sensitive to changes in the nutritional status of an individual. In the examined group of footballers, the lowest values of both indices were observed in midfielders, while defenders displayed the greatest body mass and cell mass when taking body height into consideration. The obtained results may be further justified by the observed ascendency of the mesomorphic somatotype of defenders [29]. Extracellular mass contains all the metabolically inactive body tissues, and thus an increased ECM/BCM index value is frequently interpreted as a sign of malnutrition. However, a different trend is observed among football players, who feature a decrease in the relative amount of extracellular mass [30]. This has been linked to physical activity that requires larger power output, such as in endurance running and cross country skiing. In the group of football players examined in this study, the overall ECM/BCM index was found to be 0.7, which corresponds to those values in well-trained adult competitors [31]. When considering playing positions, the lowest index value was observed in forwards, while midfielders were characterised by the highest level of extracellular mass in relation to cell mass. The easiest way to measure the reaction of the cardiovascular system to effort is to determine the heart rate index, which has been significantly correlated to VO 2max and blood lactate and saliva lactate levels. Heart rate reserve is also used as an indirect measurement of the intensity of metabolic changes and useful when comparing the endurance of players in different positions on the pitch [32]. The group of youth football players analysed in this study featured no statistically significant variation between resting heart rate, maximum heart rate or heart rate reserve. However, it should be emphasised that forwards displayed the lowest HR rest and the highest HR max and HRR during the test. Defenders were characterised by the highest values of resting heart rate and the lowest values of maximum heart rate and heart rate reserve. Based on the obtained results, it can be concluded that forwards are characterised by the highest level of cardio-vascular efficiency. Research conducted on year-old football players revealed that forwards were characterised by greater endurance, velocity, agility and power, along with better muscle development and body leanness, than other players [33]. Goalkeepers, on the other hand, were characterised with greater height, mass, body fat and the lowest aerobic capacity. Midfielders displayed greater levels of agility and endurance, while defenders were characterised by the lowest body fat. Conclusions Analysis of the results revealed that there are certain differentiating trends in body tissue composition and cardiovascular efficiency among football players playing in different positions. Forwards were characterised by having the greatest height, highest levels of active body 99

8 A. Burdukiewicz et al., Body composition and functional traits tissue development and the most efficient cardiovascular systems. Defenders displayed larger body build, while midfielders were characterised by significantly higher values of extracellular mass and EMC in relation to BCM. These differences reflect the varied physical efforts players perform during a match and should be taken into consideration when designing training programmes. References 1. Wisloff U., Helgerud J., Hoff J., Strength and endurance of elite soccer players. Med Sci Sports Exerc, 1998, 30, Gorostiaga E.M., Izquierdo M., Ruesta M., Iribarren J., González-Badillo J.J., Ibáñez J., Strength training effects on physical performance and serum hormones in young soccer players. Eur J Appl Physiol, 2004, 91, , doi: /s y. 3. McMillan K., Helgerud J., Macdonald R., Hoff J., Physiological adaptations to soccer specific endurance training in professional youth soccer players. 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9 A. Burdukiewicz et al., Body composition and functional traits 29. Orhan Ö., Sağir M., Zorba E., Kishali N. F., A comparison of somatotypical values from the players of two football teams playing in Turkcell Turkish super league on the basis of the players positions. J Phys Educ Sport Manag, 2010, 1, Randáková R., Effect of regular training on body composition and physical performance in young cross-country skiers: as compared with normal controls. Acta Univ Palacki Olomuc Gymn, 2005, 35, Bunc V., Body composition as a determining factor in the aerobic fitness and physical performance of Czech children. Acta Univ Palacki Olomuc Gymn, 2006, 36, Impellizzeri F.M., Rampinini E., Marcora S.M., Physiological assessment of aerobic training in soccer. J Sports Sci, 2005, 23, , doi: / Gil S.M., GIL J., Ruiz F., Irazusta A., Irazusta J., Physiological and anthropometric characteristics of young soccer players according to their playing position: Relevance for the selection process. J Strength Cond Res, 2007, 21, , doi: /R Paper received by the Editors: June 19, 2012 Paper accepted for publication: March 12, 2013 Correspondence address Anna Burdukiewicz Akademia Wychowania Fizycznego al. I.J. Paderewskiego Wrocław, Poland aburdukiewicz@gmail.com 101

10 2013, vol. 14 (2), Gender-based dimorphism of aerobic and anaerobic capacity and physical activity preferences in deaf children and adolescents doi: /humo Anna Zwierzchowska The Jerzy Kukuczka Academy of Physical Education, Katowice, Poland Abstract Purpose. Research on the hearing impaired has revealed that the rate of change of physical fitness characteristics between both genders may be different than that of the hearing. The aim of the study was to verify the gender-based differentiation of aerobic and anaerobic capacity in a group of deaf children and adolescents (aged years) and to evaluate their physical activity preferences. Methods. A semi-longitudinal study was conducted, with data collected three times over a period of two years. Aerobic capacity was measured by the PWC 170 cycle test, anaerobic capacity by the Wingate test. A questionnaire was used to evaluate the physical activity preferences and favored leisure activities of the participants. Results. Significant genderbased differences were found in the aerobic and anaerobic capacity of the deaf boys and girls. A moderate correlation was noted for leisure time preferences. Conclusions. Deaf children feature no gender-based differences among their physical activity preferences. Environment plays a major role in stimulating the behavior of deaf children and adolescents. Key words: aerobic and anaerobic capacity, sexual (gender) dimorphism, deafness Introduction Disabilities, especially those that affect the musculoskeletal system, play a large role in reducing physical activity levels. However, often at times individuals with sensory impairments are not perceived as having the same limitations in performing physical activity as those with physical disabilities. This is especially so with hearing impairments, which are usually not regarded as limiting physical activity, although research on this subject has provided contradictory results. Many researchers state that the physical abilities of the deaf are highly differentiated and even sometimes lower than those found among an average hearing population [1 5], concluding that this may be the consequence of how physical education is shaped and taught to the deaf. A study by Ellis [6] revealed that one of the most important factors motivating deaf youth in performing physical activity is the emotional support and involvement of parents. A similar conclusion was reached by Dummer et al. [2], stating that there are no differences in the motor skills of deaf children and their hearing peers. This group of authors believes that the introduction of early intervention and special education programs already at the preschool age helped bridge any supposed impediment. Moreover, they recognized that environmental factors (type of school, lifestyle, parental attitude as well as their involvement in physical activity, and the availability of free play opportunities) also play an important role in motor development. Liberman et al. [4, 7] drew attention to the importance of several environmental factors, in particular on how physical education classes were conducted through the use of special programs and the role of physical education teachers in providing a behavioral role model for participation in physical education. An additional factor noticed by auxologists and teachers of the deaf is the difference in interest in various forms of physical activity based on gender, which is believed to be a reflection of what physical activity can actually be performed [2, 8]. Research has confirmed that the gender difference between males and females is already visible at the preschool age and includes not only interest in various forms of physical activity but also motility [9]. The ontogenetic development of motor and morphological skills has been described as highly variable. Motor skills are largely the result of environmental conditioning, hence dimorphic variation cannot be as clearly defined as in the case of somatic characteristics. Therefore, it is difficult to expect that dimorphic traits in motility would not be present even when a hearing impairment is present. However, a few studies that have been conducted on the hearing impaired found that the rate and pace of characteristics that can emerge to differentiate both genders may be different than those among the hearing [3, 10 13]. Among girls, fewer differences were found to exist between those hearing and deaf than in the case of boys. Comparative studies on the physical development of deaf boys and girls have revealed significant differences in favor of girls. One of many conclusions reached by such studies was that deaf girls develop physical and motor skills better than boys [10 15]. It was also noted that deaf girls learn new motor skills quicker and show little or no differences when compared with their hearing peers than in the case of deaf boys. In contrast, deaf boys often showed significantly greater motor deficits than their hearing peers [2]. Haubenstricker and Seefeldt s findings [8] on the hearing helped theorize 102

11 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf that the ability to learn basic motor skills is more similar between deaf boys and girls than among their hearing peers. Instead, the delay experienced by deaf boys in learning new motor skills may be caused by them presenting a physical fitness level lower than among the hearing. The aim of this study was to verify what gender differences exist among a group of deaf children and adolescents (10 18 years old) in their ability to perform aerobic and anaerobic tasks as well as what their physical activity preferences. In light of the formulated objective, the study was guided by the following research questions: 1. What is the preferred physical activity of deaf male and female youth? 2. Is gender a factor that differentiates the deaf in their ability to perform aerobic and anaerobic tasks? It was assumed that the preferred physical activity is an important factor differentiating aerobic and anaerobic exercise capacity. Material and methods Students attending special education schools for the deaf and hard of hearing from the Polish cities of Katowice, Kraków, and Racibórz comprised the target population. A sample was selected by adopting the criteria used in modern audiology as based on Parving [16]. The main criterion for inclusion was for the student to have been diagnosed of profound hearing loss (prelingual deafness) before the age of three and experiencing sensorineural hearing impairment. All cases where the etiology of deafness was unknown were excluded from the study. All of the participants had normal intelligence as well as showed no signs of any physical disabilities that could impair movement. The final sample included deaf students of both genders within the calendar age groups of years, years, and years, where 17.7% had inherited deafness, 55.4% were prenatal cases, and 26.9% suffered a hearing impairment after the postnatal period up to age three. The study design was designed to be semi-longitudinal in nature and divided into three age groups within a year old spread. It was conducted three times in 2004, 2005, and 2006 (all in the month of October) on the same deaf students within the mentioned three age groups, allowing the same age groups to be observed ( , , and years old) (Tab. 1). A self-designed questionnaire was used to evaluate the physical activity preferences of the participants. It contained closed-ended questions with multiple-choice answers on how they enjoyed spending their leisure time. The questionnaire was completed with the help of a sign language interpreter who also provided instructions on how to complete the exercise tests measuring aerobic and anaerobic capacity. Each exercise task was preceded by a demonstration with a complete explanation of the instructions and conducted by the same research team each time. The study was approved by the Bioethics Committee of Scientific Research at the University School of Physical Education in Katowice, Poland as part of a project funded in part by the State Committee for Scientific Research. In addition, the legal guardians of the participants were informed of the nature of the experiment and provided their written consent. The participants were informed they may at any time leave the study without providing any reason and reminded that their personal information would remain private in accordance with all applicable data privacy laws. Physiological data was collected by lung vital capacity as well as the aerobic and anaerobic capacity of the participants was measured. Vital capacity (VC) was measured in l/min by use of Pony Graphic 3.7 spirometer (Cosmed, Italy). Respiratory rates were measured twice as per the manufacturer s recommendation. Prior to taking a measurement, the participant was asked to breathe calmly for a short period of time and then inhale and exhale as hard as possible, performing a maximum inhalation and maximum exhalation. After exhaling the remaining residual air volume was measured. Aerobic capacity was assessed by VO 2max kg 1 and the PWC 170 cycle test on an 828E cycle ergometer (Monark, Sweden), which from a technical point of view was the most accommodating for the participants due to their impairment. The task was thoroughly explained to the participants and motivation was provided throughout the test. First, the workload on the cycle ergometer needed to maintain a heart rate of 170 beats per minute was calculated (a higher value in the PWC 170 test denotes that more work needs to be performed based on a correctly functioning cardiovascular system). It was determined that two five-minute trails at 30 and 60 W for Table 1. Participants grouped by age and gender Year 10 (12) 13 (15) 16 (18) Girls Boys Girls Boys Girls Boys n Age in parentheses is the age of the participants at the conclusion of the study 103

12 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf girls and 50 and 100 W for boys would be adequate. Throughout the test the participants heart rate was monitored. PWC 170 was calculated by the formula: 170 f 1 PWC 170 = N 1 N 2, f 1 f 2 where: N 1 first test workload, N 2 second test workload, f 1 heart rate at the fifth minute of the first test, f 2 heart rate at the fifth minute of the second test. Maximal oxygen uptake (VO 2max ) was then estimated based on the Astrand-Ryhming nomogram by taking into consideration steady heart rate at submaximal effort [17]. This provided two variables that could be used to assess aerobic endurance: maximal aerobic power (PWC 170 [W/kg]) and and maximal oxygen uptake (VO 2max [ml/kg x min]). Anaerobic capacity was measured by the 30-second Wingate Test, which is a non-invasive method that is suitable for repeated use and considered to be a reliable and accurate measure of anaerobic capacity, as anaerobic processes meet almost 90% of the overall energy demands of the test [18]. The test also registers the power output of a participant as a function of time (throughout the 30 second period of the test) as it increases and then decreases as the effects of fatigue set in. Analysis of power output as a function of time indicates that humans produce maximum power between the first 3 6 seconds of the test, followed by steady decrease until completion. This reveals the nature of the energy conversion process in the working muscles. The test was performed with the use of a different cycle ergometer (model 829, Monark, Sweden) that measures the duration of each pedal revolution. After receiving a visual cue, the participant s task was to reach a maximum pedaling frequency as fast as possible and maintain this speed for 30 seconds. The load was matched individually to each participant by taking into account their body mass, age, and sex (75g per kg). Changes in power output were determined by the duration of each pedal revolution. The test was preceded by a five-minute warm-up on the cycle ergometer with a load suitable to reach a heart rate of beat per minute. Anaerobic capacity and power output were measured with the following variables: maximal anaerobic power MAP [W], average anaerobic power AAP [W], time to reach maximal power TMP [s], time under tension TUT [s], and the rate of power loss RPL [%]. Data were recorded and calculated by using MCE ver. 2.0 computer software. All statistical analysis was performed with Statistica v. 7.1 (Statsoft, USA) and Microsoft Excel software. The mean ( ), median, minimums and maximums, standard deviation (SD), and measures of skewness (SK) and kurtosis (KU) were calculated for data that were expressed as a ratio variable. Normal distribution was assessed with the Shapiro-Wilk test. Univariate ANOVA and correlation analysis using Spearman s rank correlation coefficient (r s ) was also used. The results were treated as statistically significant at p < The sexual dimorphism of the participants somatic characteristics were determined by the differences of the mean values in each successive year. However, several studies have shown that sexual dimorphism is more accurately measured by indicators that define body proportions and not individual morphological characteristics. Developmental differences between the studied boys and girls were determined by Mollison s index of sexual dimorphism (SDI) [19]: SDI =, SD where: SDI the indicator of sexual dimorphism, the arithmetic mean of the girls characteristics, the arithmetic mean of the boys characteristics, SD the standard deviation of the boys characteristics. Dimorphic differences were treated as significant when the difference between the means ( ) was larger than the standard deviation (SD) of the group of males. The absolute value of the tested variable would indicate the degree of differentiation: the larger the value the larger its value of one standard deviation away from the mean of the boys results. A positive value would indicate that this characteristic is in favor of females. Results The responses obtained from the questionnaire found that the boys were decidedly less physically active than the girls, with a large majority of them preferring to spend their leisure time passively by watching TV or playing computer games (94.2% and 77.7%, respectively). However, the majority of boys reported that their more actively spent leisure time consisted of bicycling and team sports (80.5%), which was in contrast with the girls who preferred calmer activities such as playing outside and taking walks (51.8%). The results of the questionnaire indicated a lack of statistically significant differences in the leisure activity preferences of the deaf boys and girls. A moderate correlation was found between the boys and girls preference for passive forms of physical activity (r s = 0.629, p < 0.05) although no significant relationships were found among active forms of physical activity (Tab. 2, 3). Physical fitness was analyzed by measuring aerobic and anaerobic capacity. Analysis of the indicators of aerobic capacity and vital capacity (VC) found a statistically significant difference between the boys and girls only in PWC 170 [W/kg]. Only the youngest group of girls 104

13 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf Passive Active Table 2. Preferred leisure activities by the deaf girls and boys Type of activity Boys n = 35 % Girls n = 27 TV Computer Reading books Social games Bicycling Swimming Taking walks, playing outdoors Skiing Team sports Table 3. Spearman s rank correlation coefficient (r s ) the deaf boys and girls with regard to their preferred leisure activities Passive leisure activities Girls Boys Girls x Boys x Active leisure activities Girls Boys Girls x Boys x % achieved better results than the boys, with the later tests finding that the boys achieved significantly better results up to the age of 18 (f = 5.6; p < 0.03). Gender had no statistically significant effect on the rate of maximal oxygen uptake, only age was a significant factor differentiating both groups. A decline of VO 2max values was noticed in both the boys and girls. A somewhat different picture is seen in the case of VC, whose values progressively rise over time, although no statistically significant differences were found between the boys and girls (Tab. 4). The sexual dimorphism index found dimorphic variation in favor of the males for PWC 170 above the age of 12 and for VC above the age of 16. It is worth noting that the dimorphism index was highly fluctuated showing no clear trend. Furthermore, the dimorphism index calculated for VO 2max pointed to no differences greater than one standard deviation away from the boys mean, which indicates that there is no significant variation between genders (Tab. 4). Analysis of the increases in PWC 170 and VO 2max finds that gender has no statistically significant effect on these values, with the only statistically significant difference found in the rate of change of vital capacity between 10 and 12 years of age (Fig. 1). The participants ability to perform brief anaerobic effort was based on the following five measured variables: maximal anaerobic power MAP [W], average anaerobic power AAP [W], time to reach maximal power TMP [s], time under tension TUT [s], and the rate of power loss RPL [%]. Significant differences between the boys and girls were found for MAP and AAP (the oldest group composed of 16-, 17-, and 18-year-olds), RPL (11- and 17-year-olds), and TMP (17-year-olds), all in favor of the boys (Tab. 5). It should be noted that the time needed to reach these values was significantly higher than expected (3 6 seconds). Anaerobic capacity assessed using the dimorphism index indicates a regular progressive trend for MAP and AAP from the age of 13 onwards, whereas the absolute values point to significant differences between genders in favor of the boys starting from the age of 16. A similar situation, although reversed, was found with RPL, which measures the rate at which fatigue sets in. This variable was found to largely characterize the girl participants (indicating a smaller tolerance to fatigue). Table 4. Aerobic capacity and vital capacity of the deaf girls and boys Age VC PWC 170 VO 2max ± SD ± SD SDI ± SD ± SD SDI ± SD ± SD SDI ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± * statistically significant difference between genders at p < 0.05; SDI Mollison s sexual dimorphism index; shaded values indicate a difference in dimorphic traits (SDI > SD ) 105

14 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf * statistically significant difference at p < 0.05 denotes change as a unit of time (year) for VC, PWC 170, and VO2max Figure 1. Rate of change for vital capacity and the indicators measuring the aerobic capacity of the deaf girls (G) and boys (B) among the three age groups (10 12, 13 15, and years old) Nonetheless, the SDI index was less than one standard deviation away from the boys means, which suggests that gender is not a differentiating factor here. The remaining variables assessing anaerobic capacity oscillated between zero and the absolute value of one standard deviation, indicating no significant differences between the genders (Tab. 5). Analysis on the rate of change of the variables measuring anaerobic capacity found that gender did have a statistically significant effect on increased TMP in the youngest age group. There were no statistically significant differences in the rate of change for the remaining variables between the two genders (Fig. 2). Table 5. Anaerobic capacity of the deaf girls and boys MAP [W/kg] AAP [W/kg] TMP [s] TUT [s] RPL [%] Age SDI SDI SDI SDI SDI ± SD ± SD ± SD ± SD ± SD ± SD ± SD ± SD ± SD ± SD ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± * statistically significant difference between genders at p < 0.05; SDI Mollison s sexual dimorphism index; shaded values indicate a difference in dimorphic traits (SDI > SD ) 106

15 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf * statistically significant difference at p < 0.05 denotes change as a unit of time (year) for maximal anaerobic power (MAP) AAP average anaerobic power TMP time to reach maximal power TUT time under tension RPL the rate of power loss Figure 2. The rate of change of variables measuring anaerobic capacity for the deaf girls (G) and boys (B) among the three age groups (10 12, 13 15, and years old) Discussion Lung vital capacity has been medically verified to increase together with maturity, although it remains highly variable not only due to age but also gender [21]. This study confirmed the progressive rise of vital capacity in both females and males, with significant gender differences emerging after the age of 15. However, no significant sexual dimorphic differences in the rate of change of this physiological variable were found to occur in this group of deaf year-olds. The progressive variability of various somatic characteristics defining human development have been found to determine individual exercise capacity. This was the most visible in the oldest group of deaf participants (16-, 17-, and 18-years-old), where gender was a factor differentiating their aerobic and anaerobic capacity with males showing a considerable advantage over their female peers. These findings correspond with the results of able-bodied young adults, due in part that the physiological adaption of children s bodies to exercise significantly differs than in mature adults. These differences are particularly noticeable in exercise performed at maximal and supramaximal intensities that use predominantly anaerobic energy processes. This is due to children having a less developed ability to resynthesize high-energy resources based on anaerobic energy processes as well as a reduced ability to neutralize the byproducts of anaerobic exercise. Hence, children obtain lower measures of maximal anaerobic power and feature less tolerance to homeostatic imbalance during physical effort [22, 23]. A study by Bar-Or [18] has also shown that children s lower levels of anaerobic capacity may be caused by reduced capacity to use muscle glycogen during physical effort. This was evidenced by a slower rate of anaerobic glycolysis and lower blood lactate concentration levels in the working muscles when compared to adults. This relationship was verified in the present study of deaf children and youth, where the potential for effort increased with age and which was most visible among the group of deaf males. In terms of the differentiation between boys and girls anaerobic capacity, Cempla and Bawelski [24] were more critical of the opinion that boys featured a greater increase in 107

16 A. Zwierzchowska, Aerobic and anaerobic capacity and physical activity of the deaf maximal anaerobic power (MAP) relative to girls, although the results obtained in this study do not confirm their assessment. Research on the physical activity of disabled children and youth has indicated that the hearing impaired do not see themselves as individuals who are dysfunctional when compared to the rest of the population. This group has been found to have very high self-esteem in regards to their habits and ability to perform physical exercise, while at the same time reporting that they do not feel to have physical ability levels lower than their hearing peers [25]. Among a group of disabled individuals, the hearing impaired presented a high level of physical fitness [26]. Nonetheless, these observations have been contradicted by a number of empirical studies on the aerobic and anaerobic capacity of the deaf in comparison with the non-disabled [11, 27, 28]. However, few have concentrated on the gender-based differences of the deaf s aerobic and anaerobic capacity. Shepard, Ward, and Lee [28] examined 15 boys and 14 girls (ages 12 to 15) finding that only 40% were found to meet the norms for their age and sex. These authors pointed out that age and gender did differentiate the results, which followed a progressive trend together with age, although these changes were statistically insignificant for the group of girls. They also drew attention to the increased adiposity of the deaf, especially in the case of females, which may have contributed to this finding. Other researchers have stated that deaf children and adolescents feature lower tolerance to effort during aerobic and anaerobic testing [11, 27]. The results of this study support this hypothesis especially in the case of females. The variable measuring power loss (RPL) was significantly lower among boys in the oldest age group, which reflects their higher (better) tolerance during short-term anaerobic exercise (Tab. 5). Here, the sexual dimorphism index had a positive value as the girls recovery process required more time, but was at the same time less than one standard deviation from the boys mean, finding that RPL was not a characteristic that differentiates gender. Of considerable interest is also one of the other analyzed variables, the time to reach maximal anaerobic power (TMP). The time to reach maximal power has been defined to occur at around 3 6 seconds. A surprising outcome in this study was that both the boys and girls had difficulty in reaching their maximum heart rate within this time frame. One of the only explanations for this result may be that this group was less motivated (volition). Motivation is an important factor not only for succeeding in sports but also, above all, guides individuals to engage in suitable fitness training. The concept of motivation has been defined as a hypothetical construct [29], as a state of readiness to take specific action stemming from both individual needs and external factors and which possesses a certain significance that cannot be completely defined through empirical evidence. Evidence of this fundamental problem can be found in the responses provided by the participants in the questionnaire on their physical activity preferences, which indicated that individual forms of physical activity were highly preferred. Yet, it is common knowledge that nothing better motivates individuals than interpersonal relationships and healthy competition. It should be taken into account that deafness is a mitigating factor in social behavior (feelings of strong alienation from both able-bodied and disabled individuals) and might have been reflected in the participants responses. For example, their preference for these forms of physical activity are consistent with those found in a group of deaf students in Karachi, Pakistan [30]. It is worth noting that the deaf students from Karachi also ranked individual sports and forms of recreation first, while rating improving health and the body the least motivating factor for their participation in physical activity. Therefore, it is difficult to expect that deaf individuals would present large differences in their preferences for various forms of physical activity as is the case for the able-bodied. The findings of this study showing a moderate correlation between girls and boys who prefer passive forms of leisure activities allow us to assume that deafness acts to limit both the preferences and motivation for physical activity and is an issue that requires further investigation. Conclusions The ability to perform increasing amounts of aerobic and anaerobic work was found to increase together with age for both the deaf male and female participants. Gender-based differences were noted for aerobic (from the age of 12) and anaerobic capacity (from the age of 14). In contrast, no statistically significant differences were observed in the rate of developmental change that defines aerobic and anaerobic capacity. The study found no differences in the physical activity preferences of the deaf boys and girls, which is believed to show that deafness is a factor that limits and, consequently, unifies what forms of physical activity the deaf prefer to engage in. It is believed that the social environment plays a large role in stimulating the behavior of deaf children and adolescents. It was found that deaf boys perform aerobic and anaerobic effort increasingly better as they get older when compared with their female peers. Based on this study s findings (TMP) and observations made during the tests, it is believed that motivation significantly affected the attained results, possibly due to communication and interpersonal difficulties. This signifies the need for providing additional external motivation for the hearing impaired when measuring exercise capacity and during physical education classes, making this a challenge to be met by both teachers and researchers. Such a conclusion was also reached by Jonsson and Gustafsson [31], who reported that motivation is an important criterion when measuring the respiratory efficiency of the hearing impaired. 108

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Jerzego Kukuczki ul Mikołowska 72a Katowice, Poland a.zwierzchowska@awf.katowice.pl 109

18 2013, vol. 14 (2), EFFECTS OF ELBOW FLEXOR MUSCLE RESISTANCE TRAINING ON STRENGTH, ENDURANCE AND PERCEIVED EXERTION doi: /humo Mauro Gonçalves 1, Anderson Souza Castelo Oliveira 2 * 1 Department of Physical Education, Bioscience Institute, São Paulo State University, Rio Claro, Brazil 2 Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark Abstract Purpose. To verify the effects of resistance training at the electromyographic fatigue threshold (EMG FT ) based on one-repetition maximum strength (1RM), heart rate (HR), rate of perceived exertion (PE) and endurance time (EndT). Methods. Nineteen subjects (training group [TG]: n = 10; control group [CG]: n = 9), performed 1-min bicep curl exercises sets at 25%, 30%, 35% and 40% 1RM. Electromyography (biceps brachii and brachiorradialis), HR and PE were registered. Biceps brachii EMGFT was used to create a load index for an eight-week resistance training programme (three sets until exhaustion/session, two sessions/week) for the TG. The CG only attended one session in the first week and another session in the last week of the eight-week training period for EndT measurement. EndT was determined from the number of repetitions of each of the three sets performed in the first and last training sessions. After training, 1RM, EMGFT, EndT, HR and PE at the different bicep curl load intensities were again measured for both groups. Results. Increases in 1RM (5.9%, p < 0.05) and EndT (> 60%, p < 0.001) after training were found. In addition, PE was reduced at all load intensities (p < 0.05), while no changes were found for HR and EMGFT after training. Conclusions. Strength-endurance training based on the EMGFT improved muscular endurance and also, to a lesser extent, muscular strength. Moreover, the reduced levels of physical exertion after training at the same intensity suggest that endurance training exercises may improve comfort while performing strength exercises. Key words: elbow flexion, electromyography, endurance, perceived exertion, training Introduction Increased muscular strength, muscular volume (hypertrophy), endurance and fat tissue loss are the usual adaptations of skeletal muscle tissue to resistance training [1, 2]. In addition, neural drive facilitation measured by analysing surface electromyography (EMG) is also reported following resistance training, which is related to increased EMG activity for agonist muscles and reduced activation for antagonist muscles [3 6]. However, the literature on the topic shows controversial results in terms of EMG activity following resistance training, some reported increased EMG [3, 4], others an absence of changes [5] and also one a reduction [4] among the trained muscles. These contrasting observations relate to different training protocols, such as training volume/ duration, session frequency and intensity [1, 4]. Unfortunately, training intensities based on EMG data have been rarely studied, even though the use of the electromyographic fatigue threshold (EMG FT ) has been previously discussed [7, 8] and suggested as an alternative training index [9]. The determination of EMG FT was originally suggested by using different load intensities performed until exhaustion, usually at one intensity per day [10]. However, * Corresponding author. Oliveira et al. [8] verified that by performing shorter sets (30 60 seconds), the EMG slopes (EMG activity vs. time) and subsequent EMG FT are similar to those obtained after more exhaustive periods of exercise. Therefore, this allows accurate EMG FT to be determined within a single session. Previous investigations that applied EMG FT as a training intensity found increased elbow flexor strength and reduced EMG activity for the biceps brachii (BB) and brachioradialis (BR) muscles and, concomitantly, reduced activity for antagonist muscles (triceps brachii) [9]. Resistance training has been associated with neuromuscular and also metabolic and/or psychological adaptations. Previous investigation has found reduced heart rate (HR) following high-repetition lower limb resistance training [11], which may suggest an attenuation in the fatigue process during exercise. For the upper limbs, previous studies have reported increases in HR and perceived exertion (PE) at higher load levels [12 14]. Oliveira et al. [9] have verified on average HR at 140bpm and PE at 8 (on a scale of 0 to 10) for bicep curls at the end of a 1-min set at 40% one repetition maximum (1RM). Thus, low load intensities can elicit significant effort demands for smaller muscular groups. Metabolic and psychological measurements such as HR and PE have been well correlated to elbow flexor EMG activity during fatiguing exercises [13, 14], which may suggest similar modulation for neuromuscular and metabolic/psychological properties during exercise 110

19 M. Gonçalves, A.S.C. Oliveira, Endurance training at EMG FT [12 14]. Based on the above, we hypothesized that resistance training focused on endurance performance, such performed at the EMG FT, can enhance time to exhaustion and reduce HR and PE. Such strength-endurance training may be aided by the use of individualized load intensities estimated from the EMG FT, which could eventually optimize endurance. Therefore, the aim of the present study was to investigate the effects of individualized resistance training on muscular endurance and metabolic/psychological demands during the bicep curl. Material and methods Nineteen healthy male (age 21 ± 1.1 years, height ± 4.3 cm, body mass 71.4 ± 7.7 kg; mean ± SD) volunteered for the experiment. The characteristics of the participants are shown in Table 1. None had been taking part in any systematic form of upper limb resistance training six months prior to the beginning of the study, and were asked to maintain their normal daily activities throughout the investigation period. All subjects were informed of the procedures, the risks and benefits associated with participating in the study and signed an informed consent term previously approved by the Local Ethics Committee. The participants were randomly divided in two groups, a training group (TG, n = 10) and a control group (CG, n = 9), and tested over a 12-week period. The testing procedure was as follows: Week 1 dynamic 1RM test was performed by both groups for the biceps curl; Week 2 EMG FT was determined during one day of testing; from Week 3 to Week 10 subjects in the TG took part in an endurance training program conducted twice a week for the elbow flexor muscles based on biceps brachii EMG FT [8]; the CG did not participate in any resistance training. The CG was asked not to participate in any resistance training during the duration of the eight-week training period, but required to attend one training session in the first and last week (Weeks 3 and 10) of the resistance training programme when endurance time (EndT) for all sets was measured for both groups. An additional 1RM test was performed at the beginning of Week 7 in order to evaluate potential strength improvements. After the training period was completed, the test procedures from the first two weeks were repeated for both groups (in Weeks 11 and 12). Table 1. Anthropometric characteristics of participants in the control group (CG: n = 9) and training group (TG: n = 10); mean ± SD Age (years) Mass (kg) Height (cm) CG 20.8 ± ± ± 3.90 TG 21.2 ± ± ± RM test and familiarization The procedure to assess maximal strength during the biceps curl exercise has been described elsewhere [9]. The initial load was set to 30kg and increased/decreased if necessary. The participants needed to perform the full range of motion, starting from a full extension in order to avoid compensation by the shoulders or trunk. Invalid trials were those in which the participant could not perform the full range of motion and/or performed trunk/shoulder compensative movements to raise the bar. The participants were familiarized with the bicep curl with a demonstration showing correct posture and movement rhythm. They were instructed to remain standing 1.5 m in front of a mirror with the trunk in a fixed position; their execution of the exercise was assisted by a frame specially designed to avoid compensation [9]. The rhythm was fixed at 40 bpm by a metronome (1.5 seconds for the concentric and 1.5 seconds for the eccentric phase of each repetition). In addition, the subjects were familiarized with the OMNI physical exertion scale [15], ranging from 0 (extremely easy) to 10 (extremely hard). This scale was positioned in front of the subject, fixed at eye height on the mirror frame. EMG FT determination, heart rate and perceived exertion The participants performed four sets of 1-min bicep curl exercises at 25%, 30%, 35% and 40% 1RM in a randomly selected order, with a 10-min rest interval provided between sets. Verbal encouragement and feedback on posture was constantly provided during movement execution. The rhythm was fixed at 40 bpm, similar to the one used in the familiarization session, and the range of motion was fixed from approximately 15 to 125 elbow flexion (0 = full elbow extension). EMG activity was recorded for the biceps brachii (BB) and brachioradialis (BR) muscles at each load intensity by using pairs of adhesive, pre-gelled silver/silver chloride Medi- Trace surface electrodes (Covidien, USA) with a 10 mm caption area placed at an inter-electrode distance of 20 mm. Surface EMG signals were recorded (model CAD 1026, Lynx, Brazil) at a 4000 Hz sampling frequency, amplified (1.000x) and band pass filtered ( Hz). Further details about EMG acquisition and calculation are available elsewhere [9]. Offline kinematic analysis, synchronized with the surface EMG measurements, were used to determine 90 elbow flexion for every concentric action. The root mean square (RMS) was calculated in a 250 ms time-window commencing at 90 elbow flexion. Linear regressions between RMS vs. time for each set were then calculated, from which the slopes and intercepts were obtained. A new linear regression model was calculated for slopes vs. load, and the intercept of this linear regression was defined as the EMG FT for each participant [9, 10]. An illustration of the methods used for EMG FT estimation is presented in Figure

20 M. Gonçalves, A.S.C. Oliveira, Endurance training at EMG FT Figure 1. Determination of electromyographic fatigue threshold (EMG FT ): surface EMG signals are recorded during bicep curls at different load intensities (A); slope of the root mean square (RMS) values for each repetition are then extracted from the linear correlations (B); second linear correlation between slopes and load intensities generates a Y-intercept, defining the EMG FT (C) HR was recorded at 15 s into the set and at its end (60 s) by using a heart rate monitor (model S150, Polar, Finland). Concomitantly, subjects were asked to numerically rate how they felt their active muscles working using the previously cited PE scale as a guide. Training program based on EMG FT The training group s resistance training programme was conducted during an eight-week period with two sessions held each week. The training sessions consisted of performing three sets of biceps curls exercise until exhaustion (failure to maintain complete range of motion and/or movement velocity/rhythm), each set was interspaced with 2-min rest. Training intensity (load) was individually determined by the biceps brachii EMG FT (%1RM). At the end of the fourth week, 1RM levels were re-evaluated in order to adjust the training intensity if necessary so as to maintain EMG FT as a percentage of the current strength. Throughout the sessions and during the sets the participants were strongly encouraged to give their maximum and maintain correct execution until exhaustion. Data was measured as mean ± SD for all variables. Two-way mixed model ANOVA was used to verify the effects of training protocol (PRE-training x POST-training within-subject factor) and group (CG x TG between-subject factor) on the dependent variables: 1RM; EMG FT for BB and BR; EndT for first, second and third sets; HR; and PE. In addition, in order to verify the effects of load intensity (25% x 30% x 35% x 40% 1RM) and exercise duration (15 s x 60 s) on HR and PE as dependent variables, two-way ANOVA was used. Tukey s post-hoc test was applied when necessary. The significance level was set at p < Results Maximal strength and EMG FT No changes in 1RM strength were found for the CG throughout the test protocol (Week 1: 36.1 ± 3.9 kg, Statistical analysis Figure 2. Biceps brachii (BB) and brachioradialis (BR) electromyographic fatigue threshold (EMG FT ) before (PRE) and after (POST) eight-week endurance training; mean ± SD 112