A knee exoskeleton harvesting different energy levels changes muscle forces during gait: revealing muscle contributions to metabolic cost of movement

It was proposed that muscle force is related to metabolic cost of gait. A knee exoskeleton, harvesting different amounts of energy, modulates the metabolic costs, during gait. We used musculoskeletal modelling and simulation to estimate muscle forces changes due to the energy harvesting levels. Mean muscle forces over the gait cycle were significantly different (p< 0.01) at most exoskeleton energy harvesting levels; moreover, the muscle force changes account for the observed metabolic cost changes over different energy harvesting levels.