Background
Female runners have a higher risk of stress fractures than male runners. Literature about best practices for preventing stress fractures in female long-distance runners is lacking. We aimed to identify which factors predict the risk of stress fractures within 6 months in female elite long-distance runners.
Study design: Cohort study.
Methods
We measured bone mineral densities (whole body and lumbar spine) and body composition using dual-energy X-ray absorptiometry (DXA) in elite female long-distance runners aged 18 to 37 years old (N = 21) who belonged to a women's track team. We followed participants prospectively for 6-month periods. Stress fractures were confirmed with bone scan, magnetic resonance imaging, and/or computed tomography findings. We used univariate logistic regression and stepwise multivariate logistic regression with the receiver operating characteristics curve to examine the ability of bone mass and body composition parameters alone or in combination to predict the occurrence of a stress fracture.
Results
We performed 118 DXA measurements. Stress fractures (four sacral, three tibial, three calcaneal, two pubic, two femoral neck, one rib, one cuboid, and one metatarsal) occurred in nine runners within 6 months. Bone mineral densities (whole body and lumbar spine), total bone mineral content, lean body mass, and percentage total bone mineral content (relative to total body mass) were significantly associated with a stress fracture developing. The multivariate analysis showed that bone mineral density of the lumbar spine alone was the strongest predictive factor. Bone mineral density of the lumbar spine <81.1% of the young adult mean predicted the occurrence of a stress fracture within 6 months, with and 88% sensitivity and 74% specificity.
Conclusion
Female elite long-distance runners with lumbar spine bone mineral density <81.1% are at increased risk of a stress fracture within 6 months and should reduce their high-impact sports activities to avoid developing a stress fracture.
Clinical relevance: The present study provides meaningful information that suggests a possible useful application of DXA measurement as a screening tool in regular medical examinations for predicting stress fractures in female long-distance runners.