STRESS FRACTURES

Report #6980; 12/21/96

45% of competitive female runners develop stress fractures, small cracks on the surface of the bones in their legs and feet. A recent study in the American Journal of Sports Medicine shows that having small calf muscles is the most common risk factor (1).

When you run, your feet hit the ground with a force equal to or greater than three times body weight, which can shatter bones. The largest bones are usually the strongest, and people with the largest bones have the largest muscles. So, runners with the smallest circumference around their calf muscles are the ones most likely to suffer stress fractures. Stress fractures usually start as a minor discomfort in the foot, lower leg or pelvis,/ that occurs near the end of a long run. Usually the pain goes away as soon as you stop running. On the next day, it hurts in the same spot earlier in the run. If it hurts to touch a spot on a bone and does not hurt an inch away, you probably have a stress fracture. Most of the time, you don't need a cast, but should stop running for the 3 to 6 weeks it takes for you to be able to run without pain. If you have to exercise, ride a bike or swim. X-rays are usually not sensitive enough to diagnose stress fractures. If your doctor wants to prove the fracture, he will order a bone scan. Other risk factors for stress factors besides having small calf muscles include restricting food and having irregular periods (2). Women with stress fractures that do not heal may need to take a bone strengthener called alindrinate or estrogen if they lack that hormone (3).

By Gabe Mirkin, M.D., for CBS Radio News