Inter-limb asymmetry across multiple soccer tasks varies with maturity status in young players: a cross-sectional study.

Biological maturation is one of the determinants influencing physical performance, yet its impact on asymmetry in soccer-specific tasks remains poorly understood. This cross-sectional study investigated the effects of biological maturation on inter-limb asymmetry in lower limb muscle volume (LLMV), linear and changeof-direction (COD) sprints (with and without the ball), jump performance, and dynamic balance. The agreement between asymmetry indices in dribbling tasks was assessed using Kappa coefficients to determine the consistency of asymmetry direction across tasks. Eighty-three young male soccer players (Pre-PHV: n = 42, Circa-PHV: n = 30, Post-PHV: n = 11) performed (1) 10-m sprint and 90° COD tests with- (S10drib and CODdrib, respectively) and without the ball (S10run and CODrun, respectively), (2) bilateral and unilateral countermovement jumps, and (3) the Y-balance test. Asymmetry indices were calculated for all performance measures. The Pre-PHV players showed greater asymmetry in S10drib, CODdrib, and CODdrib-Deficit than Circa- and Post-PHV (p < 0.05). The S10drib-Deficit asymmetry was higher in Pre-PHV players than that of Circa-PHV players (p = 0.038), while Post-PHV players had lower CODdrib asymmetry than Circa-PHV players (p = 0.016). Balance asymmetry was greater in Post-PHV players than their counterparts (p < 0.05). Kappa coefficients showed fair to moderate agreement between asymmetry directions in S10drib and CODdrib, and between their respective deficits, indicating task-specific asymmetry consistency. These findings underscore the need for maturation-specific training strategies, with early-maturing players benefiting from targeted neuromuscular training, while older players should focus on balance and sport-specific drills to manage asymmetry and injury prevention.