Title:
Long-term Effects of Altered Foot-Ankle Mechanics on Locomotion Neuromechanics and Energetics
Long-term Effects of Altered Foot-Ankle Mechanics on Locomotion Neuromechanics and Energetics
Author(s)
Schroeder, Jordyn
Advisor(s)
Sawicki, Gregory
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Abstract
Wearable devices that alter foot-ankle mechanics, such as exoskeletons and modified footwear, can change locomotion performance. For example, both passive and powered ankle exoskeletons have been shown to reduce metabolic cost of walking, while high-heeled shoes have been shown to increase metabolic cost. Previous studies provide insights on how foot-ankle devices alter biomechanics and energetics, but the mechanism linking altered foot-ankle biomechanics and whole body metabolic cost remains unclear for human walking. Additionally, little is known about how changes in loading on the biological system over long time periods my impact musculoskeletal structure. These potential changes in structure may lead to altered function over long time scales.
The goal of this thesis was to ask: 1) How do devices that change foot-ankle mechanics alter whole body metabolic cost? 2) Can relatively small changes in musculoskeletal loading over long time scales impact muscle-tendon structural properties? and, 3) How do changes in muscle-tendon structure impact locomotion function? We developed computational and experimental frameworks to investigate how acute and chronic changes to muscle-tendon mechanics impact musculoskeletal structure and whole-body energetic cost of walking.
Through our work, we showed that A) active muscle volume at the ankle can drive whole body metabolic cost of walking (in-vivo), B) the number of steps taken in passive ankle exo-skeletons (in-simulation) and modified shoes with raised heels or raised toes (in-vivo) drives calf muscle-tendon material and morphological adaptation during long-term use of devices (i.e., over months) , and C) chronic changes in calf muscle-tendon properties can profoundly impact locomotion performance (in-vivo).
Taken together, our research pushes fundamental understanding of musculoskeletal structure-function of the human foot-ankle during walking to ecologically relevant long time scales. In doing so, our research also can inform the field of wearable technology offering guiding principles for design, control and/or prescription of long term use based emerging principles of long term neuromechanical adaption of end users.
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Date Issued
2023-04-30
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Text
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Dissertation