At heel strike the rear foot is inverted which allows the heel to contact the ground at its lateral border. If you look at most shoes, the heel will be worn on the outside. Through the sub-talar joint, this allows for rapid pronation as a way to both absorb energy and unlock the foot to aid in balance. The foot is now a loose ‘bag of bones’ with the rear foot in pronation, the mid-tarsal joint unlocked, and the forefoot mobile. The rest of the leg is internally rotated. If you look at runners in mid-stance, the knee is driving medially (valgus). Through mid-stance the foot is able to adapt to uneven surfaces. As the hips move over the foot and ahead of it,