The Effect of Mental Fatigue on Risk of Falling

Slips, trips, and falls are the costliest source of disabling injuries in the workplace, costing $18.6 billion annually. The purpose of this study was to investigate the effects of mental fatigue on gait variables associated with the risk of slipping and tripping. The study also investigated the efficacy of a 10-minute rest break in mitigating the effect of mental fatigue on those variables. Twenty healthy young adults (10 males and 10 females) participated and completed two experimental sessions. The order of sessions was counter-balanced for each participant. During the mental fatigue session, participants completed a computerized mentally fatiguing task for 90 minutes and performed a set of gait trials every 15 minutes throughout the task. During the control session, participants watched an emotionally neutral documentary in place of the mentally fatiguing task. After 90 minutes of the task or documentary, participants took a 10- minute break and then completed one last set of gait trials. Risk of slipping was inferred from the required coefficient of friction, heel contact velocity, and heel contact angle. Risk of tripping was inferred from minimum toe clearance and obstacle clearance. The results showed no increase in slip or trip risk. Rest breaks appeared to decrease levels of self-reported mental fatigue. However, they did not appear to have any mitigating effect on any of the gait variables that were measured.