Determinants of bone outcomes in adolescent athletes at baseline: the PRO-BONE study

Abstract

Purpose: The determinants of areal bone mineral density (aBMD) and hip geometry 26 estimates in adolescent athletes are poorly understood. This study aimed to identify the 27 determinants of aBMD and hip geometry estimates in adolescent male athletes. Methods: 28 One hundred twenty one males (13.1±0.1 years) were measured: 41 swimmers, 37 29 footballers, 29 cyclists and 14 controls. Dual energy X-ray absorptiometry (DXA) measured 30 aBMD at lumbar spine, femoral neck (FN) and total body. Hip structural analysis evaluated 31 hip geometry estimates at the FN. Multiple linear regression examined the contribution of the 32 sports practised, stature, lean and fat mass, serum calcium and vitamin D, moderate to 33 vigorous physical activity (MVPA), vertical jump and cardiorespiratory fitness (CRF) with 34 aBMD and hip geometry estimates. Results: Region specific lean mass was the strongest 35 positive predictor of aBMD (β = 0.614 - 0.931) and football participation was the next 36 strongest predictor (β = 0.304 - 0.579). Stature (β = 0.235 - 0.380), fat mass (β = 0.189), 37 serum calcium (β = 0.103), serum vitamin D (β = 0.104 - 0.139) and vertical jump (β = 0.146 38 - 0.203) were associated with aBMD across various specific sites. All hip geometry estimates 39 were associated with lean mass (β = 0.370 - 0.568) and stature (β = 0.338 - 0.430). Football 40 participation was associated with hip cross-sectional area (β = 0.322) and MVPA (β = 0.140 - 41 0.142). CRF (β = 0.183 - 0.207) was associated with section modulus and cross-sectional 42 moment of inertia. Conclusions: Region specific lean mass is the strongest determinant of 43 aBMD and hip geometry estimates in adolescent male athletes. Football participation and 44 stature were important determinants for aBMD and hip geometry estimates while the 45 contribution of the other predictors was site specific.