Over-pronation refers to an abnormal type of motion in the foot. Pronation is a normal foot motion that helps the body to absorb shock and adapt to terrain changes. Foot pronation is seen as the arch compressing down and the foot splaying slightly outward as the foot hits the ground. Over-pronation means the foot is pronating excessively or when it should not be. Over-pronation is a concern because it can lead to foot problems such as tendonitis and arthritis, as well as knee and back pain.
One sign of over-pronation is called the "too many toes" sign. This can be seen while observing a person's feet from behind. If there is over-pronation, the toes and part of the forefoot can be seen as splaying outward from of the heel. See an example of the "too many toes" sign.
Over-pronation is usually associated with flat feet, or pes planus. To learn more about foot problems related to over-pronation, as well as how it can be alleviated, see: Flat Feet