Effect of Perceived Fatigue and Workload on Two Mobile Balance Tests

Mobile balance assessments using sensors in portable devices to objectively measure postural control have become popular in recent years. However, there is a current gap in the literature with respect to how perceived fatigue and perceived workload affect these mobile balance assessments. The purpose of this study was to measure postural control with two objective mobile balance assessments (one for static balance and one for dynamic balance) before and after a standardized fatigue protocol. Healthy participants (N=30, 33.6±14.2 years) completed perceived fatigue/workload assessments along with mobile static and dynamic balance tests before a fatigue protocol (including sprints, pushups, and step-ups) and again four times after the fatigue protocol in windows approximately 9 minutes apart. Outcome measures at each timepoint included the Rating of Perceived Exertion (RPE) for perceived fatigue, NASA Task Load Index (NASA-TLX) for perceived workload, and objective metrics from the Balance Tracking System (BTrackS) Balance Test (static balance assessment) and the AccWalker smartphone app (dynamic balance test). Repeated measures MANOVA/ANOVAs and Spearman’s rho correlations were used to examine the relationship between perceived fatigue/workload and balance before and after the fatigue protocol. The BTrackS Balance Test was affected acutely after fatigue, while AccWalker showed no changes after fatigue. RPE and NASA-TLX were significantly correlated, but nearly all balance metrics were not associated with perceived fatigue/workload. Perceived fatigue and workload acutely affect the BTrackS Balance Test, but not AccWalker, which may help with the selection of a balance test based on the desired assessment characteristics and administration time relative to physical exertion.