The tendency of the feet to roll inward toward the center of the body when walking or running is called pronation. A certain degree of pronation is normal and healthy while running, and is in fact critical for proper form. Too much or too little pronation in running, however, can cause problems like tiring easily, pain, or injuries. If the issue is not addressed with orthotics or special running shoes to correct the abnormal pronation, serious issues can arise including increased likelihood of repeated injury and structural damage to the feet and ankles.
A certain degree of pronation in running occurs naturally for everyone. The amount can vary from person to person depending on how high the arch of the foot is, with some people’s feet rolling in as much as 15 degrees. Pronation occurs when the foot strikes the ground and helps to absorb much of the shock to the body. It also helps the feet adjust to any unevenness in the running surface and to propel the runner forward to the next step.
Problems can develop when the amount of pronation in running is unusually large or small. Pronation issues can cause a runner to tire more easily, lead to pain and swelling in the feet and legs, and also cause deformations of the feet like bunions, hammertoes, and corns. Over-pronation, where the feet roll inward too far, often affects the ankles, though it can affect the knees and hips as well. People with this problem tend to get ankle tendinitis and sprains. Under-pronators, whose ankles and feet remain too rigid, typically feel more shock when their feet hit the ground and tend to get sprains from their ankles rolling outward.
Ignoring excessive pronation in running can lead to some serious problems. In addition to simply making running a more difficult and uncomfortable experience, it can also do lasting damage. Exposing ankles that do not pronate correctly to the strain of running over time can affect their stability and weaken them, making them increasingly more likely to get sprained. After awhile, the structures in the feet and ankles such as the ligaments and tendons can become permanently broken down, damaged, or deformed. In order to avoid long-term issues, people who have pronation problems should speak to a doctor and explore their options in regard to corrective footwear that can help.