Long-term rugby practice enhances bone mass and metabolism in relation with physical fitness and playing position

We attempted to clarify whether rugby was able to enhance bone mineral density (BMD) and content (BMC) of weight-bearing bones by modifying bone remodelling in relation to physical fitness in male rugby players compared to controls. 22 male international rugby players aged 20-31 years (forwards, n = 12 and backs, n = 10) were compared to 14 age-matched controls of the same ethnic origin aged 21-33 years. BMD and BMC were measured by DEXA and bone metabolism was evaluated by specific makers. Physical fitness level was analysed in parallel. Both forwards and backs exhibited significantly higher BMD (+15%, +6%, respectively) and BMC (+36%, +18%, respectively) for whole body and all examined sites, regions and segments than controls, with more pronounced difference at forwards. The difference between both groups of rugby players and controls noted for BMD became more pronounced for BMC (+52% for lower limbs). BMD and BMC values were higher in forwards than backs at total body (+9, +16%) and at stressed sites such as spine (+12%, +13%), pelvis (+10%, +11%), upper (+17% for BMC) and lower limbs (+9%, +18%). Athletes, especially forwards, presented higher concentrations of OC and CTX resulting in positive values of the uncoupling index. Total body lean mass as well as muscular strength strongly correlated with total and stressed regional sites such as spine, pelvis, and lower limbs BMD and BMC (r = 0.59, p < 0.01 to r = 0.84, p < 0.001). Similarly, OC, but not CTX, is highly correlated with the same regional and total BMD and BMC (r = 0.67 to r = 0.81, p < 0.001). Rugby participation is associated with improved physical fitness, enhanced axial and appendicular bone mass and increased bone turnover in adult athletes. Moreover, the positive bone adaptation of these athletes may be related to an increase of bone remodelling rate in favour of bone formation, especially in forwards.