https://science.sciencemag.org/content/372/6545/957 “Removing energy from a person's legs during walking may sound counterintuitive, like applying the brake in a moving car,” says Michael Shepertycky, a recent PhD graduate and lead author of the study, “but our muscles naturally remove energy while we walk, and our device helps them to do so.” https://engineering.queensu.ca/news/2021/05/unique-technology-gives-humans-a-leg-up-on-walking.html