Optimal force profiles at the center of mass to reduce the energy cost of walking with unilaterally reduced push-off

Individuals with neurological impairments (e.g., post-stroke) exhibit elevated metabolic energy costs during walking. A substantial amount of this energy could be due to the mechanical work required to redirect the body’s center of mass (COM) with each step. It has been recently found that it is possible to reduce the metabolic cost of walking by 12% in individuals post-stroke with a waist tether. Since this passive device could not control or alter the timing, we expect that there is a lot of room for improvement by optimizing force profiles to reduce metabolic cost. The purpose of this study was to investigate the effects of sinusoidal force profiles on the metabolic cost by applying horizontal propulsive forces at the COM during walking with unilaterally reduced ankle mechanical power output. Results of a case study indicate that horizontal forces applied at the COM, which coincide with the acceleration phase of the COM reduced metabolic cost by 37% during walking with restricted ankle plantarflexion range of motion and ankle power generation. Determining the optimal assistance profiles from this study could guide the development of assistive rehabilitation devices