The impact of mental fatigue on the risk of non-contact anterior cruciate ligament injury during sharp stop-jump maneuver in male college students.

Objective: The aim is to elucidate the effects of mental fatigue (MF) on lower limb biomechanics during stop-jump maneuver in healthy male college students and to evaluate its potential contribution to the heightened risk of noncontact anterior cruciate ligament injury (NC-ACLI).

Methods: Using a within-subject experimental design, MF was induced with a 45-minute Stroop task. The visual analogue scale for mental fatigue (VAS-MF), an infrared motion capture system, a three-dimensional force platform, and surface electromyography (sEMG) were employed to collect data on VAS-MF scores, as well as lower limb kinematics, kinetics, and electromyographic activity pertinent to NC-ACLI risk in 36 participants, before and after the MF induction. Paired t-tests and non-parametric statistical analyses were used for evaluation.

Results: VAS-MF scores increased significantly following MF induction (P < 0.001). After induction, participants demonstrated significant reductions in ankle dorsiflexion and knee flexion angle at the moment of peak vertical ground reaction force during stop-jump (P < 0.05). Conversely, peak vertical ground reaction force, knee extension moment, and knee abduction moment increased significantly (P < 0.05), while knee abduction and hip flexion angles remained unchanged (P > 0.05). Regarding muscle activation, rectus femoris sEMG parameters-including median frequency, mean power frequency, mean absolute value amplitude, and root mean square amplitude-were significantly elevated (P < 0.05), whereas tibialis anterior sEMG exhibited significant decreases in median frequency and mean power frequency (P < 0.05). No significant changes were observed in the sEMG signals of the biceps femoris or lateral gastrocnemius (P > 0.05).

Conclusion: MF significantly modulates certain biomechanical characteristics of the lower limb during stop-jump maneuver, potentially exacerbating the risk of NC-ACLI in healthy male college students. Targeted intervention strategies are recommended to mitigate ACL injury risks under mentally fatigued conditions.

Trial registration: This study was registered with the China Clinical Trial Registry (Registration No. ChiCTR2400093367, 2024/12/03), a WHO Level 1 registry.