Relationship among Repeated Sprint Ability, Chronological Age and Puberty in young soccer players.

The aim of this study was to analyzed the relationship of Repeated Sprinting Ability (RSA) with chronological age and puberty in 100 young soccer players (Age: 13 ± 3 yr - 160 ± 33 month-; High: 159 ± 16 cm, Weight: 49.7 ± 14.1 kg; BMI 19.2 ± 2.5 kg/m) grouped on "Pulcini" (9 - 10 yrs), "Esordienti" (11 - 12 yrs), "Giovanissimi" (13 - 14 yrs), "Allievi" (15 - 16 yrs) and "Juniores" (> 17 yrs) categories. Anthropometric (Weight, Height, BMI), RSA (7x30 m sprint with 25s active rest: Total Time -TT, the lowest sprinting time (LST) and the fatigue index percentage -%IF), and Development (Self-Administered Rating Scale for pubertal development - PDS; Puberty) parameters were measured. ANOVA among categories was applied to asses differences (p<0.05) in TT and %IF. When a significant effect was found, Bonferroni's post hoc analysis was used. Pearson correlation among all variables was calculated considering all subjects and also within categories. Among categories, statistical analysis showed a significant differences (p< 0.001) in TT and a considerable trend toward significance (p=0.06) in %IF. Significant correlations among variables was found in all subjects and within categories. In particular, TT showed large significant correlation with PDS (r=-0.66) and Puberty (r=-0.67) only in "Esordienti". This study provides useful information for the coach in order to porpose an appropriate training and to obtain the optimal training effect and to minimise the risk of injury and overtraining during the different phases of growth and maturation.