This study investigated the biomechanical effects of different change of direction (COD) angles (45°, 90°, 135°, and 180°) on lower limb joint loads and injury risk in 26 male soccer players. Using three-dimensional motion capture, force platforms, and electromyography, we analyzed joint kinetics, kinematics, and muscle activation patterns during standardized COD tasks. Data were analyzed using repeated-measures ANOVA with Bonferroni post-hoc corrections (α = 0.05), with effect sizes reported as partial eta-squared (ηp²). Results demonstrated progressive increases in peak knee abduction moment (141% from 45° to 180°) and dynamic valgus index (152% increase), with a critical nonlinear threshold at 90°. Sharper CODs (≥ 135°) produced high-risk biomechanical patterns, with 88% of participants exceeding ACL injury risk thresholds during 180° tasks compared to 19% at 45°. Earlier hamstring activation (12.3% vs. 18.7% of stance phase) and increased muscle coactivation were observed at sharper angles. These findings suggest soccer training programs should prioritize angle-specific injury prevention for CODs ≥ 135°, including progressive eccentric strengthening, neuromuscular control training, and technique modification targeting reduced knee abduction moments and enhanced dynamic stability.
Li et al. (Mon,) studied this question.