View full lesson: http://ed.ted.com/lessons/the-treadmill-s-dark-and-twisted-past-conor-heffernan The constant thud underneath your feet. The constrained space. The monotony of going nowhere fast. Running on a treadmill can certainly feel like torture, but did you know it was originally used for that very purpose? Conor Heffernan details the dark and twisted history of the treadmill. Lesson by Conor Heffernan, animation by Yukai Du.