Effects of Localized Muscle Fatigue on Risk of Occupational Slips and Falls

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DESCRIPTION (provided by applicant): Injuries associated with slip and fall accidents continue to pose a significant burden to industry, both in terms of human suffering and economic losses. A majority of occupational falls leading to injuries and deaths are a result of foot slippage and are typically experienced by laborers. The literature provides convincing arguments that localized muscle fatigue can disrupt the quality of the signal from the periphery for effective balance control during slip perturbations, and increase the risk of slips and falls. Although government, labor, and industry organizations have been working to reduce the risks of fall related injuries, workers are still broadly exposed to risks associated with fall accidents. These findings warrant the need for additional studies to provide more effective prevention strategies and design criteria for jobs and working environment to reduce occupational slip and fall accidents. This proposal addresses this need through a combination of experimental studies and biomechanical modeling. Two laboratory experiments will be conducted to quantify the effects of localized muscle fatigue on slip propensity and balance recovery. The first experiment will evaluate the effects of localized muscle fatigue on the slip initiation process while walking over a non-slippery surface. Distal limb muscles (ankle plantarflexors, knee extensors) and a combination of ankle, knee, and hip muscles will be fatigued independently on different weeks. Additionally, the effects of floor inclination, load carriage, work pace (i.e., walking speed) and age will be ascertained. The second experiment will evaluate the effects of localized muscle fatigue on the balance recovery process following slips induced by walking on an unexpectedly slippery surface. Distal limb muscles as well as proximal muscles (i.e., low back) will be fatigued independently on different weeks. The effects of floor inclination, work pace, and age will be ascertained. Fall recovery characteristics will be quantified on both the perturbed and unperturbed foot. A model will be developed to characterize balance control strategies of both perturbed and un-perturbed limbs by quantifying joint moments and power of the ankle, knee, hip, and low back. The proposed work addresses several NORA Priority Areas in the context of work-related traumatic falls. The main Priority Areas are: 1) Risk Assessment Methods; 2) Control Technology; and 3) Intervention Effectiveness Research.