Estimating the time profile of metabolic cost within the gait cycle during level and uphill walking

Using indirect calorimetry, we can measure the average cost of a stride cycle but we cannot identify which phase has the highest metabolic cost (e.g. in patients). Recent simulation methods allow estimating the time profile of metabolic cost within the stride cycle. In this study, we compare the estimations of the time profile of the metabolic cost of two simulation methods for level and uphill walking. We used the muscle-level metabolic model of Umberger to estimate the time profile of metabolic cost based on an electromyography and kinematics driven musculoskeletal simulation, and we also estimated the time profile of metabolic cost based using the joint-space model of Roberts et al. Results show that both simulations predict the change in metabolic cost between level and uphill walking similarly well but there are differences in the estimated phases with high metabolic cost.