Determinants of Sprint Ability Change During Maturation in Developing Children.

This study aimed to clarify changes in sprint ability and spatiotemporal variables with maturation in children and to identify key determinants from anthropometric and muscle strength perspectives. Ninety-eight young soccer players aged 7.6-17.9 years underwent a 30-m sprint test, anthropometric measurements, muscle thickness (MT) and maximal voluntary contraction (MVC). Maturity offset (MO) was calculated as the difference between the chronological age and estimated age at peak height velocity (PHV). Breakpoint (BP) in maximal sprint speed (MSS) development was identified at +1.1 years of MO, and the participants were classified into pre- and post-BP groups. A significant correlation was found between MSS and MO in the pre-BP group, but was no longer observed in the post-BP group. Although step length (SL) was positively correlated with MO in the pre-BP group, this correlation was not observed and step frequency (SF) showed a positive correlation in the post-BP group. Multiple regression analysis revealed that in the pre-BP group, leg length (LL) was the only significant predictor of MSS, primarily by influencing SL. By contrast, in the post-BP group, MVC and MT emerged as significant predictors of MSS, mainly by influencing SF. In conclusion, this study identified a key developmental BP at +1.1 years of MO and demonstrated a shift in the determinants of sprinting ability from reliance on anthropometric growth before this point to a dominance of neuromuscular factors.