Abstract
The purpose of this study was to examine the effect of a mentally fatiguing task on postural responses to unexpected backward perturbations in sixteen young and sixteen older women. Postural responses were characterized by center of pressure (COP) displacement, corrective COP peak velocity, and electromyography (EMG) of the medial gastrocnemius. Older women had slower reaction time (p = .002), longer EMG onset times (p = .03), larger COP displacement (p = .001), and faster COP velocity (p = .02) than younger women overall. However, only young women experienced mental fatigue (slower reaction times; p = .001) and this was accompanied by significantly faster COP velocity during the mental fatigue condition (p = .02) than the control condition. Performance of mental fatigue task, not necessarily the development of mental fatigue, affects neuromuscular activation in young women only, but does not affect the magnitude of postural response to perturbation.