There are three main phases of each step. The first phase of the step is called heel-strike. Then as you put more weight on your foot you enter the mid stance phase of the step. Finally you push off with your toes in the phase toe-off.

As the foot goes thru the three phases of gait it goes thru two main motions, pronation and supination.

The easiest way to visualize supination and pronation is to pretend you hand is a foot and turn the palm to the floor. The palm of the hand represents the bottom of your foot. As you turn your hand so that the palm is facing up you are supinating your hand. As you turn the palm back to face the floor you are pronating your hand.

Pronation is the flattening out of the arch. Pronation is also referred to as rolling in of the arch. Pronation turns the bottom of the foot toward the outside. The opposite motion is called supination. Supination results in the foot turning and putting the weight on the outside of the foot.

As the foot pronates the bones of the foot unlock. When the bones unlock they allow the foot to change shape and adapt to changes in the ground (ie uphill downhill, rocky or smooth). Supination locks the bones and allows the foot to become rigid again. Supination gets the foot ready to push-off with the toes and propel the body forward.

Biomechanical dysfunctions of the foot can be described in terms such as over-pronation, and delayed supination. Custom arch supports (orthotics) reduce foot pain limiting these excessive motions and providing foot balance.