If you are an exerciser and develop a sharp pain on a bone that hurts when you press directly on that spot and does not hurt to touch an inch away, you probably have a stress fracture. Stress fractures are very common injuries, particularly in runners. In one study, 69 percent of the stress fractures occurred in runners, eight percent in fitness class participants, five percent in racket sports, four percent in basketball players and the remainder from other activities (Clin Sports Med, 1997;16:179–196). Runners are at high risk for stress fractures of the lower legs because running fast causes the foot to hit the ground with tremendous force that can shatter bones.
X-rays Often Miss a Stress Fracture
A stress fracture is not a broken bone; it is a small crack on the surface of a bone, like a crack on an egg shell. Most of the time you do not need an X-ray or MRI to diagnose a stress fracture. X-rays usually are not sensitive enough to show the surface crack until you have had it for a week or more. After a couple weeks, an X-ray can pick up the callus that forms over the crack. An MRI (which is much more expensive) can usually pick up an early stress fracture.
Healing a Stress Fracture
Stress fractures usually start out as minor discomfort in the foot, lower leg or pelvis, and they often occur for the first time near the end of a long run. Usually the pain goes away as soon as you stop exercising. On the next day, it hurts in the same spot earlier in the run. Most of the time, you don’t need a cast or brace for a stress fracture to heal, but you should stop the exercise program that caused the problem until you can exercise without pain — usually three to six weeks. Meanwhile, you can probably switch to a non-impact exercise that does not hurt, such as cycling or swimming. If you are a competitive runner, you may be able to run in water, because the water absorbs most of the foot-strike force.
Risk Factors for Stress Fractures
• Small, thin bones: The largest bones are usually the strongest, so people with smaller bones are at increased risk for stress fractures.
• Smaller muscles: people with the largest muscles usually have the strongest bones, so people with small leg circumference at the calf muscles are more likely to suffer stress fractures.
• Weaker calf muscles: Women with stress fractures often have weaker calf muscles (Med & Sci in Sprts & Ex, December 2009). Having strong muscles can help to prevent stress fractures by absorbing more force from the foot hitting the ground during running. Distance runners often work to strengthen their calf muscles by running up hills no more than three times a week.
• Longer stride length: Taking long strides causes the greatest foot strike force, which increases stress fracture risk. Reducing stride length by ten percent reduces the force of the foot striking the ground and therefore reduces force on the lower leg bones. Shortening your stride usually will not slow you down. When your foot hits the ground, your Achilles tendon contracts to store up to 60 percent of your foot strike force. Then when you step off that foot, your Achilles tendon releases the stored energy to drive you forward. Over-striding deprives you of some of this stored energy. Since many runners take strides that are too long for them to be efficient, shortening stride length usually allows them to increase cadence, helps them to run faster and longer, and reduces risk for stress fractures.
If you develop a pain anywhere in your body that does not go away when you slow down, stop exercising immediately. Most wear-and-tear injuries of any sort give you plenty of warning and become long-term only because you continued to exercise when your body was telling you to stop for that day.
Most runners who have had a stress fracture can resume running after they heal. Most will benefit from:
• taking shorter strides at an increased cadence,
• doing some hill training to make their muscles stronger, and
• stopping a workout when they develop pain in one spot that doesn’t go away when they slow down or stop.
People with recurrent stress fractures need to be evaluated for osteoporosis and its many causes. If a bone density test shows that you have osteoporosis, your doctor may recommend bone strengthening medication (Clin J Sports Medicine, Oct 1995;5(4):246-250).
People with recurrent stress fractures should also be evaluated for:
• Overtraining syndrome,
• Vitamin D insufficiency,
• Calorie insufficiency (not eating enough food),
• In females, the triad of irregular periods, weight loss and overtraining, and
• Other medical conditions (J Orthop Surg Res, 2016;11(1):98).
If a pain persists for several months, or if stress fractures continue to recur, they may need to switch to a low-impact sport such as swimming or cycling. Cyclists usually do not suffer stress fractures but they can break bones if they get hit by a car or another cyclist.