Stress Fracture

Statistically speaking, one in five runners will get a stress fracture. The devastating injury is pretty much what it sounds like: a tiny bone fracture caused by repeated stress. That tiny fracture—which is actually many micro-fractures— can grow into larger cracks that need time and rest to heal. Stress fractures commonly occur in shins and foot bones of runners, but can also happen in hips or femurs.

Symptoms of a Stress Fracture

Mild, localized pain that increases to acute pain.
Shin splints, which are caused by inflammation along the edge of the shin bone, can be mistaken for a stress fracture. Stress fracture pain is typically more localized and often feels slightly better in the morning after a night’s rest.

Causes of a Stress Fracture

“Bones are always remodeling based on the stress placed on them,” says exercise physiologist Greg McMillan, founder of the McMillan Running Company. “Weight-bearing activities like running build bone density because the bone adds strength to withstand the stress. If, however, not enough time is given between the stress on the bone and the remodeling to build it stronger, there can become micro fractures in the bone at the site of greatest stress.” Too much stress or not enough recovery time can cause those micro-fractures to grow to full-blown breaks. This is what leads to stress fractures. (Conversely, there are also bones that can become weakened from a lack of impact.) People often think it is the impact of running that wears bones down and causes stress fractures. But studies have found that only about 20 percent of stress fractures could be connected to an increase in mileage or running on hard surfaces. While people with osteoporosis or weakened bones are more susceptible, a healthy runner can develop a stress fracture because of biomechanical factors. The muscles in the legs and hips support bones and help to prevent undue forces from bending them. This includes the piriformis, hip abductors and glutes. Strengthening those muscles can help prevent a stress fracture from occurring. Inflexibility issues, such as calf tightness, can lead to greater forces applied to shin and calf muscles. That tightness causes you to put more force on your forefoot. When it comes to stress fractures in the foot, it’s the foot muscles and metatarsals you have to worry about.

Treatment for Stress Fractures

This is no surprise, but a fractured bone needs rest. Be sure to always consult a physician if you suspect you have a fracture. An X-ray won’t always show a stress fracture early on (it will if the crack is more developed) so an MRI should be more reliable. Initially, a stress fracture needs a week or more of complete rest to allow the bone to heal. Then you can start working up to light load-bearing exercises for the next two to four weeks. This could include cross-training like swimming, aqua running or cycling, depending on the severity of the fracture. Sarah Crouch, an expert coach from Runners Connect, likes water running, as it simulates good running form in the water and keeps the heart rate high. Specifically, Crouch prescribes a fartlek pyramid. “The athlete will aqua jog easily for 15 minutes before a workout of 1-2-3-4-3-2-1 minutes at a hard effort with 2 minutes easy aqua jogging between, followed by a 15-minute easy cooldown,” advises Crouch. In the third stage of treatment, you can ease back into easy running and gradually increase your mileage and intensity, if the bone has been pain-free for at least one to two weeks, The key to treating a stress fracture is patience. If you let the bone fully heal, it (typically) will heal stronger.

Preventing Stress Fractures

Keeping your bones strong is an important part of overall bone health. There are some nutrients, like Magnesium, Vitamin K, Vitamin D and protein, that can contribute to stronger bones. But given that it’s often biomechanical factors that result in stress fractures, there’s a growing amount of research about the role muscle strength and flexibility that initially play in prevention. For example, strengthening the piriformis muscle offers support in the femur, especially when it finds itself subject to bending forces of running. For others a common cause of stress fractures is calf tightness. Tightness in the calf causes a premature lifting of the heel while running, which transfers a significant amount of force into the forefoot. In fact, one study found that individuals with tight calves were 4.6 times more likely to sustain a metatarsal stress fracture. As a result, maintaining adequate calf flexibility is essential in the treatment and prevention of metatarsal stress fractures. These issues can be addressed with strengthening and stretching exercises suited to your specific weakness and injury susceptibility.