The Effect of Muscle Fatigue on Single- and Dual-Task Walking and Obstacle-Crossing in Young Adults
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Previous research has demonstrated independent effects of fatigue or concurrent cognitive task on walking and obstacle-crossing; however, limited studies were performed to examine their combined effects and interaction. The purpose of this study was to examine changes in gait characteristics and working memory performance of healthy young adults when lower extremity muscles are fatigued, during single and dual-task walking/obstacle-crossing. Twenty-four healthy adults (11 females, 20.7±1.3 years) were recruited for the study and performed the following five tasks immediately before and after a muscle fatigue protocol in randomized order: 1) performing an N-back test, 2) walking, 3) walking while performing an N-back test, 4) obstacle-crossing, and 5) obstacle-crossing while performing an N-back test. Whole body motion data were collected from a set of twenty-nine retro-reflective markers with a 10-camera motion system. Main effects: Fatigue increased walking step width, obstacle-crossing gait velocity, and caused closer placement of leading foot to obstacle. Dual-task walking decreased gait velocity, peak forward velocity, and stride length. Dual-task obstacle-crossing decreased gait velocity, caused closer placement of leading foot to obstacle, and increased leading and trailing foot obstacle clearance. Interaction effects: When fatigued, dual-task decreased obstacle-crossing peak forward velocity and walking and obstacle-crossing N-back accuracy. When pre-fatigue, dual-task increased walking N-back accuracy but decreased obstacle-crossing N-back accuracy. During single-task, post-fatigue increased obstacle-crossing peak forward velocity and walking and obstacle-crossing N-back accuracy. During dual-task, post-fatigue decreased walking N-back accuracy. Our research supports the conclusion lower limb muscle fatigue under single- and dual-task walking and obstacle-crossing significantly affects gait characteristics and working memory performance.