Simulating ideal assistive devices to reduce the metabolic cost of running

Thomas K. Uchida, Ajay Seth, Soha Pouya, Christopher L. Dembia, Jennifer L. Hicks, Scott L. Delp

Research output: Contribution to journalArticleScientificpeer-review

96 Citations (Scopus)


Tools have been used for millions of years to augment the capabilities of the human body, allowing us to accomplish tasks that would otherwise be difficult or impossible. Powered exoskeletons and other assistive devices are sophisticated modern tools that have restored bipedal locomotion in individuals with paraplegia and have endowed unimpaired individuals with superhuman strength. Despite these successes, designing assistive devices that reduce energy consumption during running remains a substantial challenge, in part because these devices disrupt the dynamics of a complex, finely tuned biological system. Furthermore, designers have hitherto relied primarily on experiments, which cannot report muscle-level energy consumption and are fraught with practical challenges. In this study, we use OpenSim to generate muscle-driven simulations of 10 human subjects running at 2 and 5 m/s. We then add ideal, massless assistive devices to our simulations and examine the predicted changes in muscle recruitment patterns and metabolic power consumption. Our simulations suggest that an assistive device should not necessarily apply the net joint moment generated by muscles during unassisted running, and an assistive device can reduce the activity of muscles that do not cross the assisted joint. Our results corroborate and suggest biomechanical explanations for similar effects observed by experimentalists, and can be used to form hypotheses for future experimental studies. The models, simulations, and software used in this study are freely available at and can provide insight into assistive device design that complements experimental approaches.

Original languageEnglish
Article numbere0163417
JournalPLoS ONE
Issue number9
Publication statusPublished - 2016
Externally publishedYes


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