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Javier Raya-González, Luis Suárez-Arrones, Archit Navandar, Carlos Balsalobre-Fernández and Eduardo Sáez de Villarreal

soccer career (established as 18.05 [6.69] y) in soccer players 4 has caused an annual increase in the number of injuries. 5 However, most epidemiological investigations have focused on professional 6 – 8 and semiprofessional senior soccer players, 9 with the studies on young soccer players being

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Dirk Pette and Dejan Škorjanc

We compared responses of the fast extensor digitorum longus (EDL) and tibialis anterior (TA) muscles in young (15-week) and aging (101-week) male Brown Norwegian rats to 50 days of chronic low-frequency stimulation (CLFS, 10 Hz, 10 hours/day). After 50 days of CLFS, the EDL muscles of the young (22-week) and aging (108-week) rats displayed similar increases in type IIA fibers, relative concentration of myosin heavy chain MHCIIa, elevations in mitochondrial citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities, and similar decreases in glycolytic enzyme activities (glyceraldehydephosphate dehydrogenase, lactate dehydrogenase). TA muscle in young rats contained a few cytochrome c oxidase negative (COX) type I fibers. Their number was ~2-fold elevated by CLFS. Conversely, aging muscle, which contained a slightly higher amount of COX fibers than young TA muscle, responded to CLFS with a significant decrease in COX− fibers. The appearance of small COX-positive type I fibers in stimulated aging muscle indicated that regenerating type I fibers “diluted” the COX-deficient fiber population.

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Peter S.W. Davies, Jian-Ying Feng, J. Anthony Crisp, Janice M.E. Day, Ann Laidlaw, Jidi Chen and Xiao-Peng Liu

The energy expenditure and hence energy requirements of 12 young Chinese gymnasts attending a specialized school in Beijing were assessed. Total energy expenditure was measured using the doubly labeled water technique and this, in conjunction with measures of basal metabolic rate (BMR), allows the calculation of a physical activity level (PAL). Mean PAL value for the gymnasts was 1.98, which is significantly different from published mean values found in nongymnast children of a similar age. This mean value is equivalent to very heavy levels of physical activity during the periods of training being undertaken. This is the first time that energy expenditure has been noninvasively measured in free-living young gymnasts. The data will be of use to sports scientists and nutritionists alike.

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Louise A. Kelly, John J. Reilly, Diane M. Jackson, Colette Montgomery, Stanley Grant and James Y. Paton

Tracking of total physical activity (PA), moderate to vigorous activity (MVPA), and sedentary behavior was assessed in 42 young children (mean age at baseline 3.8 years) over a 2-year period using the Actigraph accelerometer. Tracking was analyzed using Spearman rank correlations, percentage agreements, and kappa statistics. Spearman rank correlations were r = .35 (p = .002) for total PA, r = .37 (p = .002) for MVPA, and r = .35 (p = .002) for sedentary behavior. Percentage agreements for PA, MVPA, and sedentary behavior were 38, 41, and 26 respectively. Kappa statistics for PA, MVPA, and sedentary behavior ranged from poor to fair. Results suggest low levels of tracking of total physical activity, MVPA, and sedentary behavior in young Scottish children over a 2-year period.

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Thierry Long, Nathalie Pantaléon, Gérard Bruant and Fabienne d’Arripe-Longueville

Based on game reasoning theory (Shields & Bredemeier, 2001) and related research, the present study aimed at describing young elite athletes’ perceptions of rules compliance and transgression in competitive settings, as well as the underlying reasons for these actions. Semi-structured interviews were conducted with 10 young elite athletes. The qualitative analysis showed that respect and transgression of rules in competitive settings were perceived to depend upon the athletes’ individual characteristics (e.g., desire to win), their social environment (e.g., coach’s pressure, team norms), sports values and virtues (e.g., fair play, the effort ethic), and modern sports rewards (e.g., media recognition, financial rewards). These results confirmed and expanded game reasoning theory and illustrated moral disengagement mechanisms (Bandura et al., 1996) in the sport domain.

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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.

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Giancarlo Condello, Carlo Minganti, Corrado Lupo, Cinzia Benvenuti, Daniele Pacini and Antonio Tessitore

The evaluation of change-of-direction (COD) performance is strongly focused on the time spent to perform the test trials, while much less is known about the technical execution adopted during the COD movements. Thus, the purposes of this study were to evaluate (1) the relationship between straight- and COD-sprint tests and (2) the technical execution of COD movements in relation to different age categories of young rugby players. Young rugby players (N = 157, age range 8–19 y) completed a test battery composed of a 15-m straight-sprint test (15SS) and a 15-m sprint test performed with 2 changes of direction (15COD). Significant differences were detected between age categories for both tests. Significant correlations were found between 15SS and 15COD. The analysis of the technical execution of the 15COD test showed differences between age categories, with a prevalence of rounded turns up to the U15 category. These findings confirmed the relationship between straight and COD abilities in young male rugby players. Moreover, the new approach introduced by this study, based on the analysis of COD technical execution, revealed that this performance could be conditioned by the age and mastery level of the players.

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Martin Buchheit, Ben M. Simpson, Esa Peltola and Alberto Mendez-Villanueva

The aim of the present study was to locate the fastest 10-m split time (Splitbest) over a 40-m sprint in relation to age and maximal sprint speed in highly trained young soccer players. Analyses were performed on 967 independent player sprints collected in 223 highly trained young football players (Under 12 to Under 18). The maximal sprint speed was defined as the average running speed during Splitbest. The distribution of the distance associated with Splitbest was affected by age (X 2 3 = 158.7, P < .001), with the older the players, the greater the proportion of 30-to-40-m Splitbest. There was, however, no between-group difference when data were adjusted for maximal sprint speed. Maximal sprint speed is the main determinant of the distance associated with Splitbest. Given the important disparity in Splitbest location within each age group, three (U12-U13) to two (U14-U18) 10-m intervals are still required to guarantee an accurate evaluation of maximal sprint speed in young players when using timing gates.

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Amber D. Mosewich, Kent C. Kowalski, Catherine M. Sabiston, Whitney A. Sedgwick and Jessica L. Tracy

Self-compassion has demonstrated many psychological benefits (Neff, 2009). In an effort to explore self-compassion as a potential resource for young women athletes, we explored relations among self-compassion, proneness to self-conscious emotions (i.e., shame, guilt-free shame, guilt, shame-free guilt, authentic pride, and hubristic pride), and potentially unhealthy self-evaluative thoughts and behaviors (i.e., social physique anxiety, obligatory exercise, objectified body consciousness, fear of failure, and fear of negative evaluation). Young women athletes (N = 151; M age = 15.1 years) participated in this study. Self-compassion was negatively related to shame proneness, guilt-free shame proneness, social physique anxiety, objectified body consciousness, fear of failure, and fear of negative evaluation. In support of theoretical propositions, self-compassion explained variance beyond self-esteem on shame proneness, guilt-free shame proneness, shame-free guilt proneness, objectified body consciousness, fear of failure, and fear of negative evaluation. Results suggest that, in addition to self-esteem promotion, self-compassion development may be beneficial in cultivating positive sport experiences for young women.

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Hans Braun, Karsten Koehler, Hans Geyer, Jens Kleinert, Joachim Mester and Wilhelm Schänzer

Little is known about the prevalence and motives of supplement use among elite young athletes who compete on national and international levels. Therefore, the current survey was performed to assess information regarding the past and present use of dietary supplements among 164 elite young athletes (16.6 ± 3.0 years of age). A 5-page questionnaire was designed to assess their past and present (last 4 weeks) use of vitamins, minerals, carbohydrate, protein, and fat supplements; sport drinks; and other ergogenic aids. Furthermore, information about motives, sources of advice, supplement sources, and supplement contamination was assessed. Eighty percent of all athletes reported using at least 1 supplement, and the prevalence of use was significantly higher in older athletes (p < .05). Among supplement users, minerals, vitamins, sport drinks, energy drinks, and carbohydrates were most frequently consumed. Only a minority of the athletes declared that they used protein/amino acids, creatine, or other ergogenic aids. Major motives for supplement use were health related, whereas performance enhancement and recommendations by others were less frequently reported. Supplements were mainly obtained from parents or by athletes themselves and were mostly purchased in pharmacies, supermarkets, and health-food stores. Among all athletes, only 36% were aware of the problem of supplement contamination. The survey shows that supplement use is common and widespread among German elite young athletes. This stands in strong contrast to recommendations by leading sport organizations against supplement use by underage athletes.