Sex Differences in Growth and Performance of Track and Field Athletes 11-15 Years Objective: To evaluate sex differences in functional performances of youth track and field athletes. Methods: Four tests of functional capacity were administered to 309 youth 11-15 years training for track and field at sport schools, 136 boys and 173 girls. Grip strength, standing long jump, 2 kg medicine ball throw and 20 m sprint were measured; height, weight and adiposity were also. Two age groups were compared, 11-13 and 14-15 years. ANCOVA was used to test sex differences by age group in the total sample (disciplines combined) and specific disciplines; age, height and weight were covariates. Results: For the total sample, males in both age groups performed better than females in the four tests but sex differences were greater among 14-15 year olds. Within disciplines, sex differences among sprinters and middle distance and distance runners were greater at 14-15 years. Results varied for general athletics; the magnitude of sex differences was similar for strength in both age groups, greater for the throw at 11-13 years and greater for the jump and sprint at 14-15 years. Conclusion: Although sex differences in performance were apparent among athletes 11-13 years, they were greater among athletes 14-15 years, reflecting to a large extent the male adolescent spurt in body size, muscle mass, strength and power. Sex differences were more established in sprinters and middle distance and distance runners, and more variable in participants in general athletics.

Purpose. The aim of the study was to evaluate and compare the physical activity patterns of preschoolers aged 6-7 years. Methods. A sample of 221 preschool children (116 boys and 105 girls) aged 6 (5.92 ± 0.30) and 7 (6.91 ± 0.25) years was recruited. Physical activity was assessed over 7 consecutive days by using pedometers to determine step counts (steps/day). Accrued anthropometric data included height, mass, and bMI. Data were compared with ANOVA to determine any significant differences between age and sex groups and the part of the week (weekday/weekend); intergroup differences were evaluated with Fisher's LSD test. A < 0.05 level of significance was adopted for all statistical tests. Results. No significant differences were found between the age groups (6-and 7-year olds). Physical activity over the 7-day period was significantly greater in the boys (13318 ± 2354 steps/day) than girls (12300 ± 2750 steps/day). Mean weekday step counts were greater among boys (13800 ± 2458 steps/day) than girls (12587 ± 2802 steps/day); this difference was statistically significant. Mean weekend steps were 12112 ± 3467 and 11579 ± 3930 steps/ day for the boys and girls, respectively. Mean weekday steps were significantly greater (p < 0.001) than mean weekend steps in both groups. The recommendation of 12000 steps/day was met by 60.6% of the sample (69.0% boys, 51.4% girls). Conclusions. Sex differences in physical activity patterns were observed in the sample of preschool children. boys, compared with girls, were characterized with a higher physical activity level on both weekdays and weekend days. Physical activity for both sexes was lower on weekend days than weekdays. The results indicate the need for improved health literacy among parents on current recommended physical activity guidelines and the suitability of a pedometer-based assessment method.

The purpose of this study was to evaluate changes in the estimated body composition of elite female and male Polish handball players during a five-week preseason training camp. Height and weight were measured, while body composition was estimated with bioelectrical impedance in 18 male and 17 female handball players before and after the five-week training protocol. Components of body composition included total body water (TBW), fat-free mass (FFM), muscle mass (MM), and absolute and relative fat mass (FM). Weight and body mass index (BMI) did not change in males, but declined in females after five weeks of training. FM and %FM declined, while estimated TBW, FFM, and MM increased significantly after training in both males and females. In contrast, comparisons of log transformed ratios for changes in weight, the BMI and body composition in males and females, respectively, suggested that estimated TBW, FFM, and MM increased relatively more in females than in males, while FM and %FM decline relatively more in males than females. Overall, the five-week preseason training program modified the body composition of male and female handball players. FM and %FM decreased, while estimated TBW, FFM, and MM increased, in both males and females after the preseason training program. Comparisons of log transformed ratios for changes in body composition in males and females suggested sexual dimorphism in response to intensive preseason training.

objective. To evaluate the growth, maturity and functional characteristics of female sport school participants 11 -15 years of age. Material and methods. The sample included 200 girls aged from 10.55 to 15.42 years. The majority (173) trained in track and field. Height, weight, three skin folds and % Fat (NIR) were measured. Grip strength, standing long jump, 2 kg medicine ball throw and 20 m sprint were tested. Athletes were compared by menarcheal status and track and field discipline with MANCOVA. Multiple linear regression analysis was used to estimate the rela tive contributions of age, height, weight and adiposity to the four functional indicators in two age groups, 11 -13 years and 14 -15 years. Results. Median age at menarche was 12.99 ± 1.11 years. None of the functional tests differed between pre-and post-menarcheal athletes 13 years, while only grip strength differed between late and early maturing athletes 14 -15 years. Height, weight and % Fat, but no performance items differed among track and field athletes by discipline. Team and individual sport athletes were heavier, fatter and stronger than track and field athletes but the latter performed better in the sprint and jump. Height, weight and adiposity accounted for significant portions of variation in the four functional indicators in each age group. conclusions. Trends in body size of female athletes attending sport schools were gene rally consistent with observations for female athletes in several sports. Percentages of variance explained in functional indicators were greater in athletes 11 -13 than 14 -15 years of age.

Purpose. To evaluate the growth and functional characteristics of male athletes 11-15 years of age. basic procedures. The sample included 190 boys, 10.5-15.4 years, undergoing training of sport schools for track and field (136) and other sports (54). Height, weight, three skinfolds and % Fat (NIR) were measured. Grip strength, standing long jump, 2 kg medicine ball throw and 20 m sprint were tested. Track and field athletes were compared by discipline and to athletes in other sports using MANCOVA (multivariate analysis of covariance). Multiple linear regression analysis was used to estimate the relative contributions of age, body size and adiposity to the four functional indicators in two age groups, those 11-13 years and 14-15 years. main findings. All variables except the standing long jump and 20 m sprint differed significantly by track and field discipline. Only height and ball throw differed among athletes in other sports. Track and field athletes had a significantly lower BMI and % Fat and performed better in the jump and sprint than athletes in other sports. Variance explained in each of the functional indicators was greater in younger than in older athletes. The sum of skinfolds and % Fat exerted a negative influence on all functional indicators. Conclusions. Trends in body size of male athletes attending sport schools were consistent with observations for youth male athletes in several sports. Height, weight and adiposity accounted for significant portions of variation in the four functional indicators in each age group, but the explained variance was higher in younger athletes.