Blog post: swansont: The Ventures Physics. Or Biology.

So we’re good walkers, or at least economic ones. But the question is, what MAKES for this efficiency? How exactly are we burning fewer calories at a specific walking pace? Ideally, this means that our muscles, like our bodies overall, are at their most efficient at a moderate walking pace. The calories burned over time are the result of the total metabolic rate of all the muscles that produce locomotion. So since your metabolism is minimized at a moderate walking pace, creating the most efficiency, it would make theoretical sense that your individual MUSCLES are also minimizing their metabolism at that moderate walking pace, and the cumulative effect is one of energy efficiency.