Effects of Localized Muscle Fatigue on Postural Control: Interactive Effects with Inclined Surfaces and Unexpected Loads, and Intervention Efficacy
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Falls in the workplace are a major cause of injuries and fatalities. Muscle fatigue is one important factor that has been linked to a decrement in postural control and a potential increased falling risk. However, potential interactive effects of muscle fatigue with other risk factors remain unclear, and practical interventions are needed to mitigate the adverse effects of muscle fatigue. The current work was conducted to address these research needs through three experimental studies. The first study investigated how muscle fatigue affects postural control during quiet standing on inclined surfaces. Inclined surfaces compromised postural control, with the most deleterious effects found while standing in a lateral direction. Fatigue did not result in further decrements in postural control during standing on inclined surfaces. The second study investigated the effects of muscle fatigue on postural control while lifting unexpected loads. Lifting an object with unexpected mass compromised postural control, with a more substantial effect found in the unexpectedly light load condition. Fatigue-related effects were not consistent, though there was evidence that lumbar muscle fatigue did not compound the adverse effects of lifting an object in unexpected mass conditions. The last study evaluated the efficacy of three interventions (two auditory stimulations and periodic rest breaks) at mitigating the adverse effects of muscle fatigue on postural control. Allowance of rest breaks did not improve postural control during the fatiguing work, though it was indicated that benefits may be present for some individuals. Both a static pure tone and moving conversation appeared to offset fatigue-induced postural instability. The current research provides a more comprehensive understanding of the contribution of muscle fatigue to fall risks during occupationally relevant tasks and assessed the efficacy of practical interventions to reduce the risk of falls. These findings may facilitate the development of strategies to prevent occupational falls related to muscle fatigue, inclined surfaces, and manual material handling tasks.
- Doctoral Dissertations