Low Bone Mineral Density and Associated Risk Factors in Elite Cyclists at Different Stages of a Professional Cycling Career

PURPOSE: To assess the prevalence of low bone mineral density (BMD) in male and female elite cyclists at different stages of a professional cycling career, and to identify potential risk factors of low BMD.METHODS: In this cross-sectional study, 93 male and female early career, advanced career, and post-career elite cyclists completed dual-energy X-ray absorptiometry at the hip, femoral neck, lumbar spine and total body, blood sampling, assessment of training history and -injuries, and the bone-specific physical activity questionnaire (BPAQ). Backward stepwise multiple regression analyses were conducted to explore associations between BMD and its potential predictors in early and advanced career (i.e. active career) cyclists.RESULTS: With a mean Z-score of -0.3 ± 0.8, -1.5 ± 1.0, and -1.0 ± 0.9, low BMD (Z-score < -1) at the lumbar spine was present in 27, 64, and 50% of the early, advanced and post-career elite male cyclists, respectively. Lumbar spine Z-scores of -0.9 ± 1.0, -1.0 ± 1.0, and 0.2 ± 1.4 in early, advanced, and post-career elite female cyclists, respectively, indicated low BMD in 45, 45 and 20% of these female subpopulations. Regression analyses identified BMI, fracture incidence, bone-specific physical activity, and triiodothyronine (T3) as the main factors associated with BMD.CONCLUSIONS: Low BMD is highly prevalent in elite cyclists, especially in early career females and advanced career males and females. These low BMD values may not fully recover after the professional cycling career, given the substantial prevalence of low BMD in retired elite cyclists. Exploratory analyses indicated that low BMD is associated with low BMI, fracture incidence, lack of bone-specific physical activity, and low energy availability in active career elite cyclists.