Pronation is the inward movement of the foot as it rolls to distribute the force of impact of the ground as you run. The foot "rolls" inward about fifteen percent, comes in complete contact with the ground, and can support your body weight without any problem. Pronation is critical to proper shock absorption, and it helps you push off evenly from the front of the foot. Although pronation is a natural movement of the foot, the size of the arch can affect its ability to roll, causing either supination (underpronation) or overpronation. If you have a normal arch, you're likely a normal pronator, meaning you'll do best in a shoe that offers moderate pronation control. People with flat feet normally overpronate, so they do well in a motion-control shoe that controls pronation. High-arched people typically underpronate, so they do best in a neutral-cushioned shoe that encourages a more natural foot motion.
During our development, the muscles, ligaments, and other soft tissue structures that hold our bones together at the joints become looser than normal. When the bones are not held tightly in place, the joints are not aligned properly, and the foot gradually turns outward at the ankle, causing the inner ankle bone to appear more prominent. The foot moves in this direction because it is the path of least resistance. It is more difficult for the foot to move in the opposite direction (this is called supination). As we develop, the muscles and ligaments accommodate to this abnormal alignment. By the time growth is complete, the pronated foot is: abnormally flexible, flat, and its outer border appears raised so that as you step down you do not come down equally across the entire foot; instead, you come down mostly on the inner border of the foot. Normal aging will produce further laxity of our muscles that causes the pronation to become gradually worse.
Over-pronation is a condition where the arch flattens out which makes the feet roll inward while walking. This condition is also known as flat feet. It imposes extreme additional stresses on the plantar fascia, a fibrous band of tissue which connects the heel to the forefoot. Over-pronation makes walking a painful experience because of the additional strain on the calves, heel and/or back. Treatment for over-pronation involves the use of specially-made orthotics which offers arch support and medial rear foot posting as corrective measures.
The best way to discover whether you have a normal gait, or if you overpronate, is to visit a specialty run shop, an exercise physiologist, a podiatrist or a physical therapist who specializes in working with athletes. A professional can analyze your gait, by watching you either walk or run, preferably on a treadmill. Some facilities can videotape your gait, then analyze the movement of your feet in slow-motion. Another (and less costly) way is to look at the bottom of an older pair of run shoes. Check the wear pattern. A person with a normal gait will generally see wear evenly across the heel and front of the shoe. A person who overpronates will likely see more wear on the OUTside of the heel and more wear on the INside of the forefoot (at the ball). A person who supinates will see wear all along the outer edges of the shoe. You can also learn about your gait by looking at your arches. Look at the shape your wet feet leave on a piece of paper or a flat walking surface.
Non Surgical Treatment
Overpronation is usually corrected with orthotics and/or strengthening exercises for the tibialis posterior. Massage treatment can relieve myofascial trigger points in the tibialis posterior, and other muscles, and address any resulting neuromuscular dysfunction in the leg or foot. Biomechanical correction of overpronation might require orthotics, neuromuscular reeducation, or gait retraining methods, as well. Stretching the gastrocnemius and soleus muscles will reduce hypertonicity in these muscles and also is essential for effective treatment. Because of impacts throughout the remainder of the body, the detrimental effects of overpronation should not be overlooked.
Depending on the severity of your condition, your surgeon may recommend one or more treatment options. Ultimately, however, it's YOUR decision as to which makes the most sense to you. There are many resources available online and elsewhere for you to research the various options and make an informed decision.