The peripheral motor repertoire as a neuromuscular constraint on walking balance integrity in age-related falls risk

点击翻译按钮获取中文摘要

PROJECT SUMMARY Despite conventional diagnostic and rehabilitative efforts, and a rich understanding of standing balance control, our rapidly aging population remains at an exceptionally high risk of debilitating falls. A major contributor to this continued risk is that most falls occur during everyday walking tasks which are much less well understood and require more complex neuromuscular coordination. Our long-term goal is to introduce a novel neuromuscular mechanism for age-associated walking balance impairment as a strategic target for diagnostic testing, earlier prevention, and rehabilitation to prevent falls in older adults. We posit that all individuals rely on a principal number of peripheral neuromuscular commands – a “peripheral motor repertoire” – to accomplish everyday walking tasks during which falls may occur (e.g., walking, turning, gait initiation, precision stepping). Supported by promising pilot data, the objective of this R21 is to rigorously test the overarching hypothesis that a reduced peripheral motor repertoire used for everyday walking tasks represents a neuromuscular constraint on older adults’ ability to successfully respond to walking balance perturbations and thereby prevent falls in the community. This cross-sectional study has three aims. Specific Aim 1 will test the hypothesis that the peripheral motor repertoire (i.e., number of motor modules or muscle synergies) used to accomplish everyday walking tasks is reduced by falls history more than by age alone and negatively correlates with the number falls in the prior year. Specific Aim 2 will quantify the association between the peripheral motor repertoire, functional balance integrity, and fear of future falls. Here, we will test the hypothesis that the size of the peripheral motor repertoire used during everyday walking tasks associates more with functional balance integrity than fear of future falls. We will interpret this finding as evidence that a reduced peripheral motor repertoire represents a neuromuscular constraint that precipitates poor balance control versus an emergent strategy associated with a fear of recurrent falls. Specific Aim 3 will test the hypothesis that a reduced peripheral motor repertoire associates with larger susceptibility to a diverse combination of sensory and mechanical balance perturbation paradigms applied during walking. We will interpret this finding as a critical mechanistic link between the peripheral motor repertoire used during everyday walking tasks and ability to accommodate balance challenges relevant to falls in the community. The proposed study is innovative, and the first to combine: (1) state-of-the-art electromyographic analyses across everyday walking tasks during which falls may occur in young adults and in older adults with and without a history of falls, (2) functional and neuropsychological measures of walking balance integrity, balance self- efficacy, and fear of future falls, and (3) a combination of sensory and mechanical balance perturbation paradigms applied during walking. This project will provide pivotal insight into a very specific and innovative feature of neuromuscular control as a mechanism for age-related balance impairment while paving the way for planned prospective studies toward more effective targets for diagnostics and rehabilitation to prevent falls.