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

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