College of Health
24 Simulating the Impact of Carbon Fiber Insoles on Gait Metabolic Cost
Elizabeth Bowman; Kota Takahashi; and Daniel Davis
Faculty Mentor: Daniel Davis (Health and Kinesiology, University of Utah)
Abstract
Carbon fiber insoles, as a low-cost assistive device, have the potential to reduce whole-body metabolic costs of walking, especially for individuals affected by conditions that increase energy expenditure (e.g. elderly, muscular disorders). Elucidating the effects of carbon fiber insoles on muscular mechanisms would facilitate design improvements to reduce injury and optimize lower limb energy expenditure. Musculoskeletal modeling and simulation provide an approach by which insights into these muscle-specific mechanisms can be examined. The aim of this study was to examine the effects of increased footwear stiffness via carbon fiber insoles on lower-limb muscle energy expenditure using computational musculoskeletal simulations. Previously captured experimental motion capture, ultrasound, and indirect calorimetry measurements during treadmill walking with three levels of footwear stiffness were used to generate simulations of a lower-extremity model with an added torsional spring. The stance phase averaged soleus fascicle shortening velocity decreased with increasing stiffness in both the experimental and simulated data. Experimental and simulated whole body metabolic cost of transport varied similarly; simulated muscle group data showed muscles crossing the ankle joint consumed less energy with increasing footwear stiffness. This initial modeling framework has the potential to understand individual muscle contributions to whole-body metabolic cost, thereby improving the design of future assistive devices aimed at reducing the energy requirements of those affected by mobility conditions.
Introduction
Humans frequently choose to walk at a speed that corresponds with the minimum energy expenditure per unit distance (i.e., termed the metabolic cost of transport) (Ralston, 1958). However, this minimum energy expenditure may increase with mobility difficulties, with approximately 10% of all U.S. adults experiencing mobility difficulties due to age, muscle disorders, and neurological conditions (Iezzoni et al., 2001). The underlying mechanism of mobility difficulties and associated increased energy expenditure is believed to be the result of altered gait patterns which can potentially lead to increased fatigue, injury risk, healthcare costs, negatively affecting an individual’s quality of life (Ataullah & De Jesus, 2024; Herrmann et al., 2024; Ko et al., 2010).
To address the relationship between mobility difficulties and energy expenditure, a number of assistive devices have been designed to reduce lower limb energy expenditure. A notable example is an unpowered ankle exoskeleton that reduced the total metabolic cost of walking by 7% (Collins et al., 2015). However, exoskeletons are often expensive, and these devices are not made fo