Impact of growth rate on physical performance and inter-limb asymmetry in young elite male soccer players.

This study examined the relationships among annual growth rate, inter-limb asymmetry, and physical performance in 129 elite youth male soccer players (U14-U19). Players were classified into three groups: fast (>7.2 cm·year⁻1; n=30), mid (3.5-7.2 cm·year⁻1; n=31), and slow (<3.5 cm·year⁻1; n=68). Assessments included bilateral and unilateral countermovement jumps (CMJ, CMJL, CMJR), sprinting, change-of-direction, isometric mid-thigh pull, and Nordic hamstring strength.Significant differences (p < 0.05) were observed in age, body mass, height, and percentage of predicted adult height (%PAH), with slow growers showing more advanced biological status. Slow growers generally outperformed the other groups in physical tests. However, no significant differences in inter-limb asymmetry were found (p > 0.05), and the directional consistency was low (Kappa: -0.23 to 0.14).The annual growth rate showed strong negative correlations with age and %PAH (r = -0.59) and moderate associations with anthropometric and performance variables (r = -0.48 to 0.45). Within the fast group, growth rate was negatively associated with CMJ and CMJR performance (r = -0.49 to -0.46).These findings highlight the importance of considering growth and maturation in youth performance, although the growth rate does not appear to influence inter-limb asymmetry.