The Effects of Subjective Fatigue on Postural Stability during Static Stances in Healthy Adults

Postural stability decreased following fatigability induced by muscular fatigue and mental fatigue. However, little research has focused on investigating the effects of subjective fatigue (perceptions of fatigue) on postural stability. This study aimed to explore the effects of subjective fatigue on postural stability by investigating the body sway during static stances in individuals with or without subjective fatigue. After completing questionnaires, forty participants divided into fatigue and control groups. They were instructed to stand barefoot on a force plate under two different visual conditions. The trajectories of the center of pressure (COP) were recorded synchronously, and the range, RMS, velocity, the area of the COP were calculated. Frequency analysis was also employed to calculate the ratio of b ody sway across different frequency bands, as well as the fractal dimension of COP to determine the complexity of body sway. Participants reporting subjective fatigue exhibited significantly higher mental fatigue, as well as larger sway range and RMS in anterior-posterior direction. Both two groups showed increased sway range, RMS and velocity in medial-lateral direction after their eyes were closed. The frequency analysis showed a decreased ratio on the MF band in anterior-posterior direction in anterior-posterior direction. The non-linear analysis showed differential change of FD between the fatigue and the control group. Fatigue primarily affected postural control in the anterior-posterior direction,, and altered the frequency characteristics and complexity of postural sway. These findings have implications may inform interventions aimed at mitigating the risk of falls or balance impairments in fatigued populations.