What causes hyperpronation?
Over-pronation (hyperpronation) is a structural problem of the foot. The head of the talus (ankle bone) is slightly rotated up so it elevates the first ray (first metatarsal and big toe). This causes the arch to collapse when weight is transferred to the forefoot. This condition can easily be demonstrated by placing a persons foot in a position where the ankle is straight (the heel is perpendicular to the floor) and noticing how the first ray is no longer in weight bearing contact with the ground. When the forefoot is made weight bearing, the arch collapses and the ankle rolls in.
