Saccades Attenuate Postural Sway Despite Muscular Fatigue Negatively Influencing Proprioception

Abstract

Background: Muscular fatigue, which reduces force output and position sense, often leads to increased sway and potential balance impairments. In contrast, saccadic eye movements can attenuate sway more than fixating gaze on an external target. The goal of this study was to determine whether the use of saccades could compensate for the increased postural sway in a fatigued state. Methods and Materials: We compared the effects of gazing at a fixation point (FP) and performing saccades (SAC) on various sway measures of the center of pressure (CoP) while participants stood as still as possible on a force plate. Participants used either a Narrow or Wide base of support (BOS) and performed 3 trials for each eye movement condition (SAC, FP) in three states (non-fatigued—NF, stretched—S, and fatigued—F). Calf rises to exhaustion induced ankle fatigue. Extreme plantar- and dorsi-flexion induced stretch. Results: SAC significantly decreased sway compared FP. F increased sway compared to NF and S states, which were similar. Conclusion: Reduced force production, which accompanies muscle fatigue and stretching, did not account for increased sway associated with acute bouts of ankle muscle fatigue. Increased position sense associated with muscle stretching apparently compensated for any reduced force output for S, while the decreased position sense explained the increased sway associated with F. Use of saccadic eye movements during quiet stance can help young adults reduce sway under NF, S, and F states.