Impact of Two Soccer Seasons on the Magnitude and Direction of Interlimb Asymmetry in Elite Youth Male Players

Abstract Ribeiro, N, Gonzalo-Skok, O, Loureiro, N, Ferreira, R, Araújo, JP, Bishop, C, and Tavares, F. Impact of two soccer seasons on the magnitude and direction of interlimb asymmetry in elite youth male players. J Strength Cond Res XX(X): 000–000, 2026—This study examined the influence of 2 competitive seasons on the magnitude and direction of interlimb asymmetry across countermovement jump (CMJ), change of direction (COD) speed, and isometric midthigh pull (IMTP) in elite male youth soccer players. A total of 60 academy players (U14–U17) were assessed at 6 time points across 2 seasons. Performance testing included unilateral CMJ, the 505 COD test, and unilateral IMTP. Biological maturation was estimated as the percentage of the predicted adult height. The magnitude of asymmetry was calculated using the standard percentage difference equation, and directional consistency was evaluated using Cohen's kappa coefficients. COD asymmetry displayed moderate-to-almost–perfect directional consistency between the first 2 time points ( κ = 0.55–0.66), but the agreement declined to poor-to-fair levels across later assessments ( κ = −0.15 to 0.32; TP3–TP6). By contrast, CMJ and IMTP demonstrated predominantly poor-to-slight directional agreement across all time points ( κ = −0.33 to 0.40), indicating substantial instability in limb dominance. Throughout the longitudinal period, maturation did not meaningfully influence asymmetry magnitude in any performance measure. Interlimb asymmetry in elite youth soccer players is dynamic, task-specific, and largely independent of the task. COD asymmetry showed brief early season directional stability, whereas CMJ and IMTP asymmetry directions fluctuated considerably over time. These findings underscore the need for repeated task-specific monitoring and caution against overinterpreting small asymmetries or assuming maturational effects on interlimb differences.