In order the correctly choose a shoe it is important to understand how your feet move during running. Basically there are two types of movement of the feet that occur during the gait cycle when running. Pronation is the natural shock absorption process that the foot uses to transfer the stress that is caused when the heel comes in contact the ground. This movement also causes the foot to become unstable, allowing for the adaptation of the foot to the surface. When the foot lands on the heel, it begins to roll forward and inwards with the body weight moving from the rearfoot to the centre of the forefoot dissipating stress and providing cushioning.
Supination is the opposite of pronation.
This movement causes the ankle joint to lock, resulting in the foot becoming a rigid lever system facilitation the propulsion necessary for movement. The arches of the feet do most of the work during running by supporting most of the body weight. The arches are 'controlled' by a combination of joints that collectively form the ankle. A runner' s foot is usually determined by structural features of their anatomy such as the positioning of their forefoot and rearfoot, and the mechanics of their lower leg and thigh movements. Most people's feet fall into one of three categories based on the degree of pronation and supination during the gait cycle.