Stress fractures: The downside of doing too much, too soon
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Stress fractures are tiny cracks in a bone. They occur during high-impact repetitive activity, when your muscles get tired and lose their ability to absorb shock. The fatigued muscles transfer the overload of stress to the bone, causing it to crack.

Any bone in your body can experience a stress fracture, but stress fractures are most common in the weight-bearing bones of your lower leg and foot. More than half of all stress fractures occur in the lower leg. Runners and tennis players get them. So do gymnasts and basketball and volleyball players, who do a lot of repetitive jumping. Women athletes are more likely than men to experience stress fractures. Flat feet or high, rigid foot arches can increase your risk. So can loss of bone mass caused by osteoporosis.

Stress fractures used to be called march fractures because they're so common among military recruits who march a lot. It's important to note that an activity doesn't have to be high-impact to cause stress fractures. Any prolonged walking or hiking can cause them.

Edward Laskowski, M.D., co-director of the Mayo Clinic Sports Medicine Center, Rochester, Minn., and a specialist in physical medicine and rehabilitation, calls stress fractures "the terrible toos." He says, "You're exercising too much, too fast, too hard for too long."

Stress fractures are more likely to happen when you first start an exercise program. "We see them in people who come out of winter hibernation and run 8 miles a day that first week of nice weather," says Dr. Laskowski.

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Know the symptoms

Left untreated, a stress fracture can grow into a more serious fracture. Be aware of the signs and symptoms of a stress fracture so that you can avoid this complication:

A specific painful spot gets worse when you apply pressure.
Pain increases over time.
Pain decreases with rest and increases with activity.
It's still painful even after resting for a few days.
Skin in the area may or may not be tender when you touch it.
Swelling may or may not be present.
You may not even notice a stress fracture when it happens. Sometime later, the area becomes painful. It may be barely noticeable at first you may feel it only during your longer, harder workouts. This is what's called a stress reaction. An actual crack in the bone may not have occurred yet. The pain you feel is a warning. Left unheeded, a microscopic crack forms. Pain increases. You feel it earlier in your workout and even when you're not exercising.

Don't do too much, too soon

You're less likely to get a stress fracture if you avoid the "terrible toos," which are particularly common among weekend warriors. "Don't do too much, too soon," says Dr. Laskowski.

Start slow and progress slowly.
Avoid sudden changes in intensity or type of exercise.
Be steady and consistent with your workouts.
Cross-train to prevent overloading any one area with the same repetitive stress. For example, you can walk 3 days of the week, then ride your bicycle or swim on the other days.
Wear good quality athletic shoes that fit properly.
Consider being evaluated for arch supports if you have flat or rigid feet or are prone to overuse injuries in your feet, ankles or legs.

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Treatment requires rest

Stress fractures can be mistaken for shin splints. But they're more serious than shin splints. The pain lasts longer and they take longer to heal. Stress fractures require more restriction of activity than shin splints do. Follow these guidelines if you experience pain:

Give your bone a break stop the activity that's causing the pain.
Ice the area to reduce swelling and pain.
Elevate the area to relieve symptoms.
Control pain with acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin).
See your doctor if pain lasts longer than 2 or 3 days.

Your doctor may:

Do a bone scan or magnetic resonance imaging (MRI) to confirm that you have a stress fracture
Prescribe pain medication if needed
Prescribe weight-bearing modifications, such as crutches or a walking boot
Prescribe physical therapy in the later stages of healing
Bone has a remarkable capacity to repair itself, but you have to give it a chance. Healing rarely occurs unless you stop the activity that caused the stress fracture, according to Dr. Laskowski.

"If you don't rest from weight-bearing and impact exercise or activity, your body won't be able to repair itself fast enough to keep up with the stress you're placing on it," he says. "The fracture may get worse, or you may significantly prolong the healing time."

Stress fractures heal themselves in a few weeks to a few months, depending on their severity and location. When they don't heal, surgery may be needed, but this is rare. Stress fractures in parts of your larger lower-leg bone (tibia) and your midfoot take a long time to heal. "For lower-extremity stress fractures, you may need to use crutches or a walking boot until you can walk normally without pain," Dr. Laskowski says.

You don't need to stop exercising if you have a stress fracture. Switch to a nonimpact exercise that keeps you fit and doesn't aggravate the fracture, such as water jogging, using a stationary bike or swimming. Once the fracture heals, slowly resume your normal exercise program.