The Advantage of Gravity

Gravity seems to pull us down and keep us in place while we run and come up. Up and down movement can be minimized by leaning the body forward while running. Such movement adds more horizontal component to the energy usage and, thus, contributes to a faster running speed with less energy expended.This trick is found in the way a runner leans but not with the waist but with the ankles. This lean gives a greater value to the x-component of the wait force giving the runner a bigger push in the direction he or she is running.