Estimated metabolic rate (% mean ± s.e.m.) of different muscle groups during level walking in our own analyses and other studies.

For the musculoskeletal estimation method, we grouped the metabolic costs of different functions similar to [20] as follows: soleus, gastrocnemius medialis and gastrocnemius lateralis for the plantarflexors, vastus medialis for the knee extensors, gluteus maximus for the hip extensors, tibialis anterior for the dorsiflexors, and biceps femoris for the knee flexors. For the joint-space estimation method, we partitioned the metabolic costs for the ankle plantar flexors/dorsiflexors, knee extensors/flexors, and hip extensors/flexors based on when the joint moments were in the corresponding direction. The metabolic rate of muscle groups in the normal walking condition from the study by Jackson et al., [18] was obtained by applying the modified Umberger [20] estimation code from [68]. The data from Roberts et al., [23] were obtained from their supplementary data file for walking at 70% of the preferred walking speed. We selected this trial from their supplementary data because the walking speed is most similar to the walking speed from our study (1 m∙s-1. We obtained the unilateral metabolic rate from the right ankle knee and hip joints by entering the data from the right ankle knee and hip as inputs to their MATLAB code and entering signals with zeros for all non-lower limb joints and all joints on the left side of the body.