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Robert W. Meyers, Jonathan L. Oliver, Michael G. Hughes, John B. Cronin and Rhodri S. Lloyd

The purpose of this study was to examine the natural development of the mechanical features of sprint performance in relation to maturation within a large cohort of boys. Three hundred and thirty-six boys (11-15 years) were analyzed for sprint performance and maturation. Maximal speed, stride length (SL), stride frequency (SF), flight time (FT) and contact time (CT) were assessed during a 30m sprint. Five maturation groups (G1-5) were established based on age from peak height velocity (PHV) where G1=>2.5years pre-PHV, G2 = 2.49-1.5years pre-PHV, G3 = 1.49-0.5years pre-PHV, G4 = 0.49years pre- to 0.5years post-PHV and G5 = 0.51-1.5years post-PHV. There was no difference in maximal speed between G1, G2 and G3 but those in G4 and G5 were significantly faster (p < .05) than G1-3. Significant increases (p < .05) in SL were observed between groups with advancing maturation, except G4 and G5 (p > .05). SF decreased while CT increased (both p < .05) between G1, G2 and G3, but no further significant changes (p > .05) were observed for either variable between G3, G4 and G5. While G1-3 increased their SL, concomitant decreases in SF and increases in CT prevented them from improving maximal speed. Maximal sprint speed appears to develop around and post-PHV as SF and CT begin to stabilize, with increases in maximal sprint speed in maturing boys being underpinned by increasing SL.

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Daisuke Kume, Akira Iguchi and Hiroshi Endoh

this study, we aimed to compare the relative exercise intensity at which the onset of accelerated muscle deoxygenation occurs during the 20mSRT between boys and men and examined whether the timing of the onset of acceleration appearance is related to 20mSRT performance in boys. Methods Participants

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Zackary S. Cicone, Oleg A. Sinelnikov and Michael R. Esco

. Lehmann M , Keul J , Korsten-Reck U . The influence of graduated treadmill exercise on plasma catecholamines, aerobic and anaerobic capacity in boys and adults . Eur J Appl Physiol Occup Physiol . 1980 ; 47 ( 3 ): 301 – 11 . doi:10.1007/BF00422476 15. Londeree BR , Moeschberger ML

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Ryu Nagahara, Yohei Takai, Miki Haramura, Mirai Mizutani, Akifumi Matsuo, Hiroaki Kanehisa and Tetsuo Fukunaga

). Therefore, increased stature and force-producing capabilities with maturation seem likely to underpin improvements in sprint performance throughout development. Evaluating the magnitude of the vertical impulse during sprinting with boys across a large age range will clarify whether the age-related increase

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Daniel das Virgens Chagas and Luiz Alberto Batista

motor coordination and physical activity. In one such investigation, Morrison et al. ( 2012 ) found that body fat percentage influenced the association between motor coordination and physical activity levels in primary school girls, but not in boys. In a study of adolescents that was not gender specific

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Amy Tischler and Nate McCaughtry

The purpose of this study was to examine boys’ perceptions of masculinity hierarchies in adventure physical education in relation to past experiences in sport-based physical education and their evolving views about physical activity in their lives. Theoretical principles of masculinity guided this study. Data were collected with 55 male high school students through 84 formal interviews, 200 e-mail interviews, and 135 ninety-minute class observations over 15 weeks. Data were analyzed using constant comparison with frequent member checks to facilitate trustworthiness. Three main findings emerged. First, boys described masculinity hierarchies in many past sport-based physical education classes as static and well-pronounced, which for many negatively impacted their perceptions of and engagement with physical activity. Second, boys described masculinity hierarchies in adventure physical education at Apex High School as shifting and narrowing, which stood in stark contrast to the inequitable status differentials in many sport-based physical education classes. Third, shifting and narrowing masculinity hierarchies resulted in significant positive outcomes for boys, most notably enhancing their orientations toward physical activity. Findings from this study suggest that physical education settings that produce shifting and narrowing masculinity hierarchies can enhance boys’ perceptions of and engagement with physical activity both in and out of school.

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Carlos Marta, Ana R. Alves, Pedro T. Esteves, Natalina Casanova, Daniel Marinho, Henrique P. Neiva, Roberto Aguado-Jimenez, Alicia M. Alonso-Martínez, Mikel Izquierdo and Mário C. Marques

conditions ( 10 ). Accordingly, the present study aimed to determine the effects of ST versus traditional strength training on explosive strength in prepubescent boys. Methods Subjects The sample consisted of 57 prepubescent boys aged between 10 and 11 years old (from fifth and sixth grades) in a Portuguese

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Stephen Heung-Sang Wong and Feng-Hua Sun

The purpose of the current study was to examine the effect of flavor on voluntary drinking and thermoregulatory responses in Chinese boys and girls exercising intermittently in a hot environment. Fourteen boys and girls (9 to 11 years old) performed four 3-hour intermittent exercise sessions (20-min walking sessions at 50% VO2peak followed by a 25-minute rest period) in a hot and humid environment (~30 °C ambient temperature and ~70% relative humidity). The participants consumed 1 of 4 beverages ad libitum in a randomized sequence by using a Latin-square principle: unflavored water (W), orange-flavored water (OF), lemon-flavored water (LF), and grape-flavored water (GF). No differences were observed in the total fluid intake (W vs. OF vs. LF vs. GF: Boys, 441 ± 114 vs. 493 ± 106 vs. 387 ± 83 vs. 568 ± 146 ml; Girls, 613 ± 131 vs. 923 ± 204 vs. 825 ± 157 vs. 790 ± 166 ml), urine and sweat output, and physiological perceptual variables among trials and between sexes. The results suggested that Chinese children can maintain body fluid balance while exercising moderately in a hot and humid environment by ad libitum drinking. The flavor of the beverages had no impact on the voluntary drinking and the state of hydration in the current study.

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Tony Adebero, Brandon John McKinlay, Alexandros Theocharidis, Zach Root, Andrea R. Josse, Panagiota Klentrou and Bareket Falk

been examined in youth. Therefore, the purpose of this study was to examine salivary and serum concentrations of cortisol and testosterone at rest and in response to an intense multitask exercise, simulating a full competitive swimming training and session, in boys versus men. Methods Participants The

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Keith Tolfrey, Alice Emily Thackray and Laura Ann Barrett

Exaggerated postprandial triacylglycerol concentrations (TAG) independently predict future cardiovascular events. Acute exercise and diet interventions attenuate postprandial TAG in adults. This paper aims to examine the exercise postprandial lipemia studies published to date in young people. Nine studies satisfied the inclusion criteria adopted for this summary. The majority of studies are in boys (22% girls) and have shown a single ~60-min session of moderate-intensity exercise, performed 12-18 hours before a standardized meal, reduces postprandial TAG. Manipulations of exercise duration and intensity suggest an exercise energy expenditure dose-dependent response is not supported directly in healthy young people. Studies investigating alternative exercise bouts have reported lower postprandial TAG after simulated intermittent games activity, high-intensity interval running and cumulative 10-min blocks over several hours, which may appeal to the spontaneous physical activity habits of young people. Although extension of these initial findings is warranted, exercise may be an effective strategy to promote regular benefits in TAG metabolism in children and adolescents; this may contribute to an improved cardiovascular disease risk profile early in life.