Trajectories of 10 m Sprint Time and Countermovement Jump Height Relative to Peak Height Velocity in Male Youth Soccer Players.

Kalata, M, Lukavsky, J, Martinho, DV, Williams, CA, Konarski, JM, Zahalka, F, Malina, RM, and Maly, T. Trajectories of 10 m sprint time and countermovement jump height relative to peak height velocity in male youth soccer players. J Strength Cond Res XX(X): 000-000, 2026-To characterize the longitudinal development of 10 m sprint time and countermovement jump (CMJ) height across adolescence in youth male soccer players. Twenty academy players (10.9-16.0 years) were assessed longitudinally over 4-5 years, comprising 145 CMJ and 140 sprint observations. Age at peak height velocity (PHV) for each player was estimated from longitudinal stature records collected at 6-month intervals, by identifying the interval of maximal annual growth and noting its midpoint. Developmental trajectories were aligned relative to years from PHV (Δage) and analyzed using Generalized Additive Mixed Models. Inference was based on estimated trajectories and associated uncertainty. Countermovement jump performance followed a nonlinear trajectory, with a maximal rate of improvement occurring shortly after PHV (+0.20 years; +3.06 cm·y-1). By contrast, early acceleration improved at a relatively constant rate across the observed maturity interval (∼0.04 seconds·y-1), with no clear nonlinear feature around PHV in this data set. No significant relationship was noted between the individual CMJ and 10 m sprint gains (r = 0.04; p = 0.80). The existence, timing, and magnitude of accelerated development of these motor skills are task-specific. Peak height velocity-aligned monitoring may help contextualize periods of more rapid CMJ development in this cohort, whereas sprint acceleration followed a more gradual trajectory across adolescence.