Mend Physical Therapy Blog and Injury Information

What Causes Stress Fractures In Female Runners?

June 22, 2023

Running remains one of the most popular outdoor activities in Boulder County. Each day in our Boulder Physical Therapy and Lafayette Physical Therapy offices we help runners return to full training and competition. Research has shown up to 90% of runners reports missing training or competition due to injury. Although most of the running injuries are not severe in nature some involving the bone can become serious if not diagnosed and treated quickly.

In short, stress fractures occur when loading of a bone outpaces the bone’s ability to heal and recover. This injury is often seen in runners who report a training error (either too much too soon or too little for too long followed by a quick start into training). In addition, some athletes may be at higher risk based on their history including female sex, prior history of a stress fracture, as well as, bone, nutrition, and/or menstrual cycle abnormalities.

A recent study in the International Journal of Sports Physical Therapy (IJSPT. 2023) aimed to compare the relative risk of runners’ demographics with the development of a future stress fracture. Authors conducted an online survey of over 1600 female runners (average age 40) of which 25% reported a stress fracture. This latter group was compared against their peers without stress fractures to determine risk. Authors reported having runners with a history of osteopenia, shin splints, or tendon injuries were at 4,3, or 1.5 times greater risk of future injury. In addition training factors were also found to place runners at risk. Female runners running > 20 miles per week or training with a running coach placed them almost twice as likely to have a stress fracture. In contrast, normal menstrual cycles, use of calcium and vitamin D reduced the risk of stress fractures. Interestingly, after the stress fracture was diagnosed only 50% of injured runners made changes to their training including mileage reductions or cross training. Even less (1/3) began a strength training program.