How Push-off Influences Energetics and Mechanics of Human Walking.

Energetic cost of walking;Biomechanics;Ankle push-off;Dynamic walking model;Mechanical Engineering;Engineering;Mechanical Engineering

Huang, Tzu-weiGillespie, Brent ;

University of Michigan

关键词: Energetic cost of walking;    Biomechanics;    Ankle push-off;    Dynamic walking model;    Mechanical Engineering;    Engineering;    Mechanical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/110443/windg_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The energetic cost of walking is important for mobility. The energetic cost of normal healthy people walking has been shown as a minimization objective for determining some gait parameters, but there lacks of understanding about the energetic cost for people walking with challenging conditions or various disabilities. It is well known that the energetic cost of walking with carried load increases substantively. Also, patients with ankle weakness due to pathologies have greater energetic cost of walking. Several prosthetic feet and ankle-foot orthoses (AFO) use elastic spring to restore ankle function by performing elastic push-off. However, there still lacks of mechanistic explanation how and why the energetic cost increases in these cases, and how the elastic push-off affect the energetic cost. In this thesis, I proposed mechanistic models for the energetic cost of human walking with carried load, with reduced push-off and with elastic push-off and then tested the model predictions with human subjects.Three dynamic walking models were used to predict the energetic cost of these conditions. First, I used a rigid-leg walking model to predict the energetic cost of walking with carried load at different speed. The rigid-leg model can only predict the mechanical work of walking but cannot predict some gait parameters, such as double support duration, so I secondly used a compliant-leg walking model to offer complimentary explanations for walking with carried load. The same rigid-leg walking model was also used to predict the energetic cost of walking with reduced push-off. Finally, I used the springy ankle walking model to predict the energetic cost of walking with elastic push-off. I then measure the mechanical work performed by lower limb extremity and estimate the metabolic cost of healthy subjects walking with carried load, with restricted ankle and with compliant artificial feet to test the predictions. The results of the experiments agreed with the predictions from the dynamic walking models. I found the energetic cost of these tasks can be explained by the mechanical work performed by lower extremity. The push-off greatly affects the energetic cost by modulating the heel-strike collision.