Stress fractures

Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also develop from normal use of a bone that's weakened by a condition such as osteoporosis.

Stress fractures are most common in the weight-bearing bones of the lower leg and foot. Track and field athletes and military recruits who carry heavy packs over long distances are at highest risk, but anyone can sustain a stress fracture. If you start a new exercise program, for example, you might develop stress fractures if you do too much too soon.

At first, you might barely notice the pain associated with a stress fracture, but it tends to worsen with time. The tenderness usually starts at a specific spot and decreases during rest. You might have swelling around the painful area.

Contact your doctor if your pain becomes severe or if you feel pain even when resting or at night.

Stress fractures often result from increasing the amount or intensity of an activity too quickly.

Bone adapts gradually to increased loads through remodeling, a normal process that speeds up when the load on the bone increases. During remodeling, bone tissue is destroyed (resorption), then rebuilt.

Bones subjected to unaccustomed force without enough time for recovery resorb cells faster than your body can replace them, which makes you more susceptible to stress fractures.

Factors that can increase your risk of stress fractures include:

• Certain sports. Stress fractures are more common in people who engage in high-impact sports, such as track and field, basketball, tennis, dance or gymnastics.
• Increased activity. Stress fractures often occur in people who suddenly shift from a sedentary lifestyle to an active training regimen or who rapidly increase the intensity, duration or frequency of training sessions.
• Sex. Women, especially those who have abnormal or absent menstrual periods, are at higher risk of developing stress fractures.
• Foot problems. People who have flat feet or high, rigid arches are more likely to develop stress fractures. Worn footwear contributes to the problem.
• Weakened bones. Conditions such as osteoporosis can weaken your bones and make it easier for stress fractures to occur.
• Previous stress fractures. Having had one or more stress fractures puts you at higher risk of having more.
• Lack of nutrients. Eating disorders and lack of vitamin D and calcium can make bones more likely to develop stress fractures.

Some stress fractures don't heal properly, which can cause chronic problems. If underlying causes are not taken care of, you may be at higher risk of additional stress fractures.

Simple steps can help you prevent stress fractures.

• Make changes slowly. Start any new exercise program slowly and progress gradually. Avoid increasing the amount you exercise by more than 10% a week.
• Use proper footwear. Make sure your shoes fit well and are appropriate for your activity. If you have flat feet, ask your doctor about arch supports for your shoes.
• Cross-train. Add low-impact activities to your exercise regimen to avoid repetitively stressing a particular part of your body.
• Get proper nutrition. To keep your bones strong, make sure your diet includes enough calcium, vitamin D and other nutrients.