Pronation / Supination

Pronation:

 Pronation is the rotation of the medial bones in the midtarsal region of the foot inward and downward so that in walking the foot tends to come down on its inner margin. 

Supination:

 Supination (or under-pronation) is the opposite of pronation and refers to the outward roll of the foot during normal motion. A natural amount of supination  occurs during the push-off phase of the running gait as the heel lifts  off the ground and the forefoot and toes are used to propel the body  forward.