This is a video of world champion hurdler Grant Holloway running the 110-meter hurdles but with his head stabilized to stay in the middle of the frame. It shows how little up and down movement actually occurs when hurdlers are “jumping” over the hurdles. It’s more like their heads are continually moving forward and their bodies just fold in half. It reminds me of those videos showing how chickens stabilize their heads when being moved around. Maybe somebody should pick up Grant Holloway and shake him around and see if his head also sticks in one place.