 The structure of the human foot and lower leg is very efficient at absorbing the shock of landing and turning the energy of the fall into forward motion, through the springing action of the foot's natural arch.Scientists studying runners' foot motions have observed striking differences between habitually shod runners (wearing shoes) and barefoot runners.The foot of habitually shod runners typically lands with an initial heel strike, while the foot of a barefoot runner lands with a more springy step on the middle, or on the ball of the foot.