Female runners get more stress fractures than men, and new research points to risk factors

August 18th, 2020
By: JobsTherapy.com Content Staff

Female runners are at least twice as likely as men to sustain stress fractures due to their training, and new research has identified several risk factors associated with this higher incidence of injury. Stress fractures affect about 20 percent of recreational runners, but they are of particular concern for women given that 54 percent of runners are female, according to the 2018 National Runner Survey.

In a study published in the journal Sports Health, researchers at Thomas Jefferson University looked at physical differences between women runners that might make some more susceptible to stress fractures. Separately, the researchers surveyed women runners to learn about their training regimens and behaviors that may contribute to stress fractures. That study was published in the journal Physical Therapy in Sport.

The findings were reported by News Medical, an online publication sharing the latest research with health-care professionals, researchers and consumers.

The same group of 40 female recreational runners ages 18 to 65 participated in both studies, News Medical reported, with half of them having sustained a stress fracture due to running and half of them having no such history. The study into physiological factors looked at traits such as bone structure and density, muscle mass and hormonal status, while the survey of women focused on factors such as training intensity, nutrition, a lack of strength training and ignoring pain.

“This mixed-methods approach provides a richer context and a more detailed picture of the practices and risks that contribute to stress fractures in everyday women runners,” Dr. Jeremy Close, associate professor of family and sports medicine at Thomas Jefferson University, told News Medical. “It also tells us how perceived risk informs physiological risk.”

In the study of physical factors, participants underwent blood tests to determine their levels of hormones, such as estradiol and testosterone; vitamins and minerals that support bone health, such as vitamin D and calcium; and bone markers. They also had their bone mineral density examined through dual-energy X-ray absorptiometry (DXA) testing, News Medical reported.

The researchers found that women who had sustained stress fractures reported menstrual changes or irregular periods resulting from their training or during peak training times, according to News Medical. In addition, the blood panel, which examined markers for bone formation and resorption, pointed to increased bone turnover in women with stress fractures.

The DXA testing revealed that women with a history of stress fractures had lower hip-bone mineral density than those who hadn’t been injured, suggesting that decreased bone strength could augment the risk of injury, News Medical reported.

“DXA for bone density and blood testing for bone markers are not routinely performed in this population – they are usually reserved for post-menopausal women – so we may be missing important clinical indicators for stress fractures in these women,” Dr. Therese Johnston, a professor in the university’s Department of Physical Therapy, told News Medical. “While the link between menstrual changes and bone strength is unclear, our findings also indicate that asking female runners about any menstrual irregularities during heavier training times is important during routine screening.”

For the survey of women runners, researchers interviewed participants to learn which factors they thought were associated with stress fractures or maintaining bone health while running, News Medical reported. Women who had sustained stress fractures reported that they had increased the intensity of their training more quickly than the other group. In addition, the group that had been injured was less likely to have maintained a proper diet and engaged in adequate strength training to complement their running.

Perhaps most significantly, women who had sustained stress fractures were more likely to have pushed through pain and injury to keep up with their running regimen, News Medical reported.

“In the interviews, it sounded like these women had trouble knowing which pain was normal and which pain was abnormal,” Johnston told News Medical. “They also reported not always receiving appropriate guidance from health-care providers on how to progress running safely.”

“It is clear that there needs to be more guidance from health-care providers for women runners on how to prevent stress fractures,” Close told News Medical. “It can be very frustrating for these women who are on a path to wellness but are impeded by an injury that can take several months to heal. If they don’t have the proper guidance on how to return to running safely, they risk a second injury.”

Johnston, the lead author on both studies, plans to continue her research by studying women with acute stress fractures as they begin running again, News Medical reported. The goal is to identify factors related to a successful or unsuccessful return to running following a stress fracture.

“We hope that our findings will encourage more thorough and routine screening in women runners for bone density and strength,” Johnston said of the two published studies, “as well as a comprehensive education plan on how to balance running with cross-training and how to interpret pain cues from the body to help women differentiate between normal aches and pains and indicators of a serious injury.”

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