The impact of physical-mental mixed fatigue on landing biomechanics inter-joint coordination and injury risk in elite American football players.

OBJECTIVE

This study aimed to investigate the effects of physical-mental mixed fatigue (PMF) on lower limb Biomechanics, Inter-joint Coordination and potential injury risk during landing task in elite American football players.

METHODS

Twelve male collegiate American football players were recruited. A randomized crossover controlled design was employed, wherein participants randomly completed baseline testing, physical fatigue (PF) intervention, and PMF intervention. PMF was induced utilizing a cycle ergometer protocol concurrently performed with a Stroop cognitive task. Kinematic and kinetic data during a landing task were synchronously collected using a Vicon motion capture system and force plates. Statistical comparisons were performed using repeated-measures analysis of variance.

RESULTS

PMF specifically altered ankle joint kinematic patterns, manifested as a decreased ankle dorsiflexion angle (p < 0.05) and an increased inversion angle (p < 0.05) at the instant of peak vertical ground reaction force (vGRF), alongside an increased peak inversion angle throughout the landing cycle (p < 0.05). However, neither PMF nor PF significantly affected hip or knee kinematics, joint range of motion (RoM), joint contribution strategy, lower limb coordination indices, or landing impact load indicators (p > 0.05).

CONCLUSION

The findings suggest that PMF specifically disrupts ankle biomechanics, potentially predisposing the joint to a posture that may be associated with higher injury risk. Nevertheless, highly trained athletes may utilize adaptive compensatory strategies developed through long-term training to maintain overall landing stability and impact load levels, thereby potentially offsetting the negative effects of PMF on neuromuscular control. When assessing injury risk associated with PMF, joint-level kinematic changes should be emphasized in addition to global indicators.