Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Health and Rehabilitation Sciences

Collaborative Specialization

Musculoskeletal Health Research

Supervisor

Garland, Jayne

Abstract

Balance is an important determinant of physical function and falls risk. This study sought to determine the effect of unilateral and bilateral perturbations, with and without cognitive load, on leg muscle activity in healthy young and older adults, as well as identify the influence of ankle power on postural and functional performance. Using a split-belt treadmill system, participants experienced unilateral and bilateral accelerations of the treadmill, without and with the Stroop test. Surface electromyography (EMG) from eight lower limb muscles was recorded from the right leg. EMG onset latency following perturbation onset, and root mean square of the muscle bursts were calculated for each perturbation. Unlike young adults, older adults did not demonstrate a distal to proximal muscle activation, suggesting that older adults adopt a unique response to postural perturbations – a response prioritized over cognitive load. Further, a higher level of ankle muscle power favoured better balance in older adults.

Summary for Lay Audience

Balance is an important determinant of physical function and falls risk. This study sought to determine the effect of slips (single [unilateral] or double [bilateral] limb), with and without a cognitive task, on leg muscle activity in healthy young and older adults. We also sought to identify the influence of ankle power (force x velocity) on postural and functional performance. Using a split-belt treadmill system, participants experienced unilateral and bilateral accelerations of the treadmill (i.e. accelerating one belt or both belts), without and with a cognitive test. Muscle activity from eight lower limb muscles were recorded from the right leg. The timing of muscle activity following acceleration onset, and magnitude of the muscle bursts were calculated for each acceleration. Young and older adults demonstrate different patterns of muscle activity, suggesting that older adults adopt a unique response to postural accelerations – a response prioritized over cognitive load. Further, a higher level of ankle muscle power favoured better balance in older adults.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Available for download on Friday, August 14, 2020

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