Conclusions
Overall, our results showed that the MTP and midtarsal joints are strongly coupled during walking, both kinematically and kinetically. This was evidenced by the consistent and proportional changes in magnitude and timing noted at both joints. We also demonstrated that foot energetics can be modulated by altering MTP motion, but the effects should not be viewed in isolation, as energy demands changed at both joints. In particular, the increase in midtarsal negative work, delayed transition to positive work, and reduced positive work need more study to fully understand their implications. This understanding is critical to our ability to enhance locomotor energetics through rehabilitation, footwear, prostheses, or other assistive devices.