Factors associated with bone health in long distance runners: a cross-sectional study

Running is mechanistically purported to be deleterious for bone health, yet few studies have examined this relationship with robust radiological outcomes. We examined the relationship between running and bone health. Males (n = 81) aged 36-79 years who reported running for 1-60 years at an average of 2.4-152.9 km/week on 1-6 days were included in this cross-sectional study. Outcomes were bone mineral density (lumbar spine, total hip, femoral neck) via dual-energy x-ray absorptiometry. Predictors were historic (questionnaire) and current (actigraphy) physical activity. Mutually adjusted associations were examined via stepwise multiple linear regression. For bone mineral density (g/cm²), associations were light physical activity (β [95%CI]: -0.012 [-0.019, -0.004]) and energy expenditure (0.00008 [0.00003, 0.00014]) for lumbar spine; light physical activity (-0.010 [-0.016, -0.003]), years of running (0.003 [0.001, 0.005]) and energy expenditure (0.00006 [0.00001, 0.00010]) for total hip; and light physical activity (-0.011 [ 0.016, 0.005]) and energy expenditure (0.00006 [0.00002, 0.00010]) for femoral neck. Associations were similar for t-scores, yet z-scores were associated with years of running at each site, rather than energy expenditure. In this study greater energy expenditure and years of running were associated with better bone health, especially among older runners. Conversely, greater amounts of light physical activity were associated with poorer bone health, especially in younger runners. These observations suggest a more nuanced view, indicating that the relationship between long-distance running and bone health is more complex than previously assumed and support the notion that prospective cohort studies examining the causal relationship between running and bone health are warranted. This study examined the relationship between running and bone health in 81 males aged 36-79 years. Results showed that greater energy expenditure and years of running were linked to better bone mineral density, while light physical activity was associated with poorer bone mineral density. These findings challenge the idea that running harms bone health.