Cause of Supination
Supination is the rolling of the foot to the outside during normal walking or running motions. The term is usually used in connection with over-supination, which means that the arch of the foot is too high and too much weight is placed on the outside of the foot. If you are a "supinator," you may be at risk for injuries such as Achilles tendinitis, peroneal tendinitis, ankle sprains and iliotibial (IT) band syndrome.
Common signs of supination are high arches and consistent wear on the outside bottom of the shoes. Looking at the wear pattern on the bottom of your running shoes is a good way to check for supination, although additional symptoms are usually present. Supinators tend to have tight calf muscles and iliotibial (IT) bands, callouses or bunions on the outside of the foot or fifth toe, and foot pain, especially in the heel and ball of the foot. They may also be more prone to "rolling" the ankle or ankle sprains.
Supination is generally caused by the bio-mechanical alignment of the bones in the lower extremities. It is usually present from birth and noticeable at a young age, unless caused by a specific injury or neuromuscular disorder. The two main forms of bio-mechanical variation that give rise to supination are the high arch, or cavus foot type, and inversion of the lower legs, often called "bow-leggedness."
Although the alignment of the bones giving rise to supination is genetically predetermined, other factors can make supination worse. Tightening of the calf muscles, for instance, tends to reinforce the movement pattern caused by supination, potentially aggravating the situation. Unstable, weak ankles also magnify the effect of supination by allowing the ankle and foot to roll more easily to the outside. Footwear that does not provide enough shock absorption places further stress on the heels and arches.
Risk of Injuries
The main risk of injury stems from the fact that a supinated foot provides less flexibility and shock absorption than normal. For runners, this usually means a hard heel strike and stress on the arch of the foot, which can lead to foot and ankle pain as well as pain in the knees, hips and lower back. Common injuries associated with supination include tendinitis, plantar fasciitis, ankle sprains and sometimes stress fractures.
Treatment and Preventing Complications
Supinators should wear shoes that provide extra cushioning to make up for the lack of shock absorption by their feet. Shoes with supportive arches can also be beneficial. Having a professional analyze your gait may be helpful before selecting your next pair of running or walking shoes. If supination becomes bothersome, your doctor may prescribe custom orthotic devices that will help redistribute the weight on your feet and absorb shock more effectively.
Always make sure you stretch the muscles in your legs, especially after exercise while your muscles are warm. Focus on the calves, hamstrings and IT band. Exercises that help strengthen the ankles will reduce the risk of injury from supination. Practice balancing on one foot or on an unstable surface, and try moving your ankles in circles or writing the alphabet in the air with your foot.
Andrea Johnson is a certified personal trainer and lifestyle and weight management consultant through the American Council on Exercise (ACE). She has a B.A. in biology from the University of St. Thomas, St. Paul, Minn., and also a J.D. from the University of Minnesota. She began writing for various online publications after four years working as a personal trainer and wellness coach.