University of Virginia Health System

At the start of each new year, many of us who have put on a few extra pounds over the holidays will resolve to begin a new exercise program. This may include using a new piece of exercise equipment or starting a running program. Any sudden increase in activity can expose the skeleton to unaccustomed stresses and may result in a painful condition known as stress fracture.

Stress fractures occur through areas of bone that have been weakened by the body's natural remodeling process. In attempt to strengthen bone in response to increased stress, the body first absorbs some of the existing normal bone so that stronger bone can then be deposited. Microscopic fractures can then occur in the weakened bone, resulting in pain and activation of the normal healing process for a broken bone. It is rare for the bone to actually break completely; the diagnosis is usually made when the healing process, rather than a fracture line, is seen on an x-ray.

Stress fractures are essentially always the results of a change or an increase in activity. This may be as subtle as adding a few miles or hills to the running route, training in worn out shoes that have lost their cushioning, or adding weight work or plyometrics to a training regimen. Stress fractures usually occur in the legs or feet and symptoms of localized pain and tenderness will usually begin about three weeks after starting a new activity. Women with low bone density (as a result of amenorrhea, eating disorders, hormonal dysfunction or menopause) are at particular risk for suffering a stress fracture.

If your doctor suspects a stress fracture, a radiograph (x-ray) will usually be the first test ordered. The standard x-ray is usually normal at first and a bone scan or MRI scan might be needed to confirm the presence of a stress fracture. Stress fractures are treated by temporary protection and restriction of activity, usually with crutches or a brace. Pool exercises and cycling may be substituted for weight-bearing exercise in order to maintain fitness. Surgery is rarely necessary, unless the signs are ignored and the stress fracture is neglected.

Prevention

• Start any new activity slowly at first. If you have not been running in a while, don't run more than a mile the first time out. Gradually increase your mileage and don't try to run through pain in the first few weeks. If you have a new treadmill, stair-stepper or rowing machine, start at low settings for ten minutes and gradually increase the intensity of your workouts.
• Use good equipment. Modern running shoes with good cushioning will decrease the risk of stress fracture. Even the best running shoes will lose much of their shock-absorbing ability after three to six months of use and should then be replaced.
• Eat a balanced diet. Good nutrition is essential for preserving normal bone density. Most Americans don't get enough calcium in their diets. With all of the low-fat options now available, there is no longer any reason to avoid dairy products in the diet. Eating disorders increase the risk of stress fracture.
• Avoid overtraining. Training or exercising too hard is counterproductive, as overuse injuries such as stress fractures will eventually lead to time lost from training. The young female athlete who trains to the point that she stops normal menstrual function is at risk for decreased bone density and stress fracture. Stress fractures and other overuse injuries account for the fact that Girls Cross-Country has the highest injury rate of any high school sport, including football.
• Don't ignore pain. Persistent localized pain in the foot, shin or groin may be the first sign of a stress fracture. The pain of a stress fracture is usually worst in the morning and during the first few steps of a run. The pain will often get better after the athlete warms up, only to return with a vengeance about a mile into a run. You should contact your doctor if you develop any of these symptoms. We have seen promising athletic careers end prematurely by stress fractures that have been ignored or under-treated.

Remember, exercise is supposed to be both fun and beneficial. By simply introducing new activities gradually, the common overuse injuries can usually be avoided.