The end of midstance is heel-lift of the support limb. Stability of the limb is required at this point and to achieve this the foot must be in a position to lock the midtarsal joint. Toe-off is at a 2 degree supinated position. The leg moves into swing phase. During this phase the foot pronates first and then supinates.
Pronation shortens the foot, which helps it to clear the ground.
Pronation also minimizes the energy expenditure necessary for ground clearance as the non-weight bearing limb passes the weightbearing limb. Supination stabilizes the bony architecture of the foot thus preparing it for heel strike, when the foot must absorb the shock of striking the ground . Transmission of the forces through the Kinetic Foot During the stance phase of gait, weight passes through the ankle and then through the stable bones of the foot to the ground. Prior to any bone supporting weight, it must first be stable against a more proximal bone, and second, it must be stabilized against a more distal bone or against the ground. An unstable bone will not support weight, and will be placed in motion by the forces acting upon it.