Lower Limb Muscle Fatigue Perturbs Gait Balance during Dual-Task Walking

Abstract

Walking and simultaneously performing an attention demanding task may occur concurrently with increasing muscle fatigue toward the end of some daily activities or job performance. Although previous research have demonstrated independent effect of these factors, their interaction are rarely taken into consideration. PURPOSE: To examine changes in gait balance and working memory performance in healthy college-age adults after lower extremity muscle fatigue. METHODS: Ten healthy adults (5 females, 20.6±1.0 yrs) performed the following three tasks before and after a muscle fatigue protocol: 1) Walking with a self-selected pace, 2) Sitting and performing a 3-back test, in which participants listened a series of digits over a loudspeaker and were instructed to verbally respond “yes” whenever a digit is heard that is the same as presented three positions back in the series, and 3) Walking and performing a 3-back test simultaneously. Sit-to-stand task at a pace of 0.5 Hz was performed to induce muscle fatigue. Maximal voluntary isometric strength of knee extensors was assessed using Biodex before and after the fatigue protocol and at the end of study. Whole body motion data were collected from a set of 29 retro-reflective markers placed on bony landmarks with a 10-camera motion system. Gait balance control was examined using the total medial-lateral CoM displacement (M-LCoM). Two-way ANOVA with repeated measures were used to detect differences between single and dual-task conditions. RESULTS: An average of 21% knee extensor strength reduction was observed immediately after the completion of fatigue protocol, and it was recovered to approximately 10% by the end of study. In both gait conditions, M-LCoM was found to increase significantly after fatigue (3.1±0.2 vs. 3.7±0.3 cm, p = .01). Accuracy of the 3-back test was not significantly affected by the fatigue or gait condition. CONCLUSIONS: Our preliminary findings indicated that gait balance control, as measured by the CoM sway, during a dual-task gait task might be more sensitively affected by the acute muscle fatigue induced in the current study.