Investigation of a passive inter-limb device on step-to-step transition of human walking

In walking like an inverted pendulum, the step-to-step transition period requires a substantial amount of simultaneous positive and negative mechanical work to redirect the center of mass between steps and it was considered as a major determinant of gait in terms of metabolic expenditure. In the current study, we developed a passive inter-limb device that transfers energy between the legs during the step-to-step transition period. By effectively transferring the energy dissipated at heel-strike from the leading leg to the trailing leg which is performing push-off, we hypothesize that the mechanical cost of transport (COT) will be reduced. Consequently, the lower limb muscles are required to do less positive and negative work, resulting in a reduced metabolic COT. Data from five subjects walking at 1.2m/s on an instrumented treadmill with the device active and passive was collected. It was found that the mechanical COT during the step-to-step transition period was reduced when walking with the device active. However, contrary to our hypothesis the metabolic COT increased when walking with the device active.