This week is an in-between-isode,* taking a pause from interviews to bring you this news flash: you know that feeling when your step is light and springy, and other times when you feel like a sack of bricks? It's not in your head. Today, we take a quick peek at the anatomy and physiology of fascia, collagen, stored energy and what that could mean for your running, walking, and stylish footwear.

*Thanks, Tim Ferris.