https://twitter.com/SDiDuro/status/817955526873059328

“Note to self: Legs don’t swing back and forth when running, they go through a cycling motion.” – SDiduro, https://twitter.com/SDiDuro/status/817955526873059328

// Commentary Corner: 

While the difference between the two animations might not be immediately apparent, you can most easily see the change by focusing on the knees and the motion of the lower leg relative to that.