Fatigue experienced by individuals with multiple sclerosis (MS) during activities of daily living affects their balance and increases the risk of falls. The aim was to assess the effect of fatigue induced by a functional task on balance control in individuals with MS. The study involved 10 individuals with MS and 10 gender-matched healthy volunteers who performed a functional sit-to-stand task using a standardized chair and metronome until they reported an inability to continue. Motor Control and Sensory Organization tests were implemented using Dynamic Posturography three times: before, immediately after fatigue, and after a 30-min rest period. The Motor Control Test revealed that individuals with MS, compared to healthy controls, showed significantly longer latencies during small, medium, and large amplitudes of backward perturbation. Longer latencies were observed in the MS group after fatigue, specifically during small and large amplitudes of forward perturbations. The Sensory Organization Test discovered that following fatigue, the MS group demonstrated significantly lower equilibrium scores compared with healthy controls in the following conditions: eyes closed (p < .001), sway-referenced visual surround (p = .02), and sway-referenced support surface (p = .03). Functional fatigue induced by sit-to-stand tasks significantly impacted outcomes of both the Motor Control and Sensory Organization tests of balance control in individuals with MS. These findings lay the groundwork for future investigations into the role of fatigue in balance control in individuals with MS.
Keywords: dynamic posturography; mobility; perturbation; postural responses.