The impact of mental fatigue on drop landing injury risk and lower limb asymmetry in elite collegiate american football players

This study investigated the impact of mental fatigue on lower limb biomechanics and bilateral asymmetry during drop landings in elite collegiate American football players to assess injury risk implications. Twelve elite male players performed bilateral drop landings before and after a 45-minute Stroop task. Data were analyzed using a 2 × 2 repeated-measures ANOVA. Irrespective of mental fatigue, the dominant limb exhibited significantly smaller hip flexion, larger peak vertical ground reaction force, and longer time to vertical ground reaction force peak compared to the non-dominant limb. Following mental fatigue, knee flexion range of motion and peak vertical ground reaction force increased bilaterally, and the non-dominant limb specifically demonstrated greater knee varus/valgus range of motion compared to baseline. While the symmetry index indicated baseline asymmetry, mental fatigue exerted no significant effect on global symmetry index. We conclude that mental fatigue impairs landing mechanics through limb-specific constraints rather than systemic symmetry collapse. Because localized compensatory mechanisms can preserve the overall symmetry index, relying solely on global symmetry metrics may mask underlying, joint-specific injury risks under mental fatigue. Consequently, athletic screening should prioritize the sensorimotor resilience of the non-dominant limb.