Effects of Mental Fatigue on Shoulder and Knee Joint Repositioning in Healthy College-Aged Males: A Quasi-Experimental Study.

Mental fatigue negatively affects both cognitive and physical performance, but its specific impact on proprioception remains underexplored. This study examined the effects of mental fatigue on shoulder and knee joint repositioning. Proprioception was assessed in 18 college-aged males using a joint repositioning task in a single-group, nonrandomised quasi-experimental design, with measurements taken before and after a Stroop task designed to induce mental fatigue. A significant increase in shoulder flexion variable error was observed (pre-Stroop = 2.79 ± 1.31°, post-Stroop = 4.97 ± 3.20°; rank biserial correlation = ‒0.673; p = .010), indicating reduced proprioceptive consistency. No significant differences were found for knee flexion variable error (pre-Stroop = 4.99 ± 3.73°, post-Stroop = 4.44 ± 2.66°; Cohen's d = 0.188; p = .435), shoulder absolute error (pre-Stroop = 4.39 ± 2.83°, post-Stroop = 6.18 ± 3.71°; Cohen's d = ‒0.413; p = .098), or knee absolute error (pre-Stroop = 4.82 ± 2.79°, post-Stroop = 5.75 ± 1.93°; Cohen's d = ‒0.328; p = .182). A secondary correlational analysis found no significant relationships between changes in mental fatigue and changes in proprioceptive measures. These findings suggest that mental fatigue may impair upper limb proprioception. Further research is needed to examine whether similar effects occur in other joints and populations. Understanding this relationship may have implications for motor control, injury risk, and performance in clinical and athletic contexts.