Measures of Balance Performance Are Affected by a Rested Versus Fatigued Testing Condition in People With Multiple Sclerosis

ObjectiveTo investigate the effects of a rested and fatigued testing condition on measures of balance in people with multiple sclerosis (MS).DesignProspective observational study.SettingAcademic research laboratory.ParticipantsFifteen ambulatory adults with relapsing remitting or secondary progressive MS with moderate disability.MethodsMeasures of postural control, dynamic balance, and fatigue were assessed during a “rested” and “fatigued” testing condition on separate days.Main Outcome MeasurementsStatic posturography was used to assess postural control. The Mini-Balance Evaluation Systems Test and Dynamic Gait Index were used to assess dynamic balance. The chronic fatigue level was measured by using the Fatigue Severity Scale, and acute fatigue was assessed by using a visual analog scale at multiple time points during testing.ResultsDuring the fatigued condition, the participants reported a significant (P < .05) increase in acute fatigue levels (visual analog scale) and demonstrated a significant (P < .05) decrease in performance on measures of postural control and dynamic balance when compared with the rested condition. However, no significant relationship was identified between the changes in fatigue and changes in balance performance.ConclusionsMeasures of balance performance and acute fatigue may be affected by rested versus fatigued testing conditions in people with MS. However, no significant relationships between changes in balance and fatigue were identified. Therefore, clinicians should use caution when making assumptions about the influence of fatigue on balance performance and should test for individual responses. Clinicians and researchers should also consider controlling for factors such as time of day and prior physical activity when administering standardized measures of balance in people with MS.