Abstract / Summary
Abstract Introduction Adolescence is a critical period for skeletal development, yet in adolescent athletes the relative contribution of lean and fat mass to areal bone mineral density (aBMD) across skeletal sites remains unclear. This cross-sectional study examined sex-specific differences in body composition and aBMD and evaluated the relative associations of lean and fat mass with aBMD in adolescent team sport athletes. Materials and Methods Two hundred two adolescent athletes (126 boys, 76 girls; 16.4 ± 0.4 years) underwent whole-body dual-energy X-ray absorptiometry. Appendicular lean mass index and fat mass index were derived, and aBMD was assessed at the total body, lumbar spine (L1–L4), and femoral neck. Multivariable linear regression models with sex interaction terms and linear contrasts were applied. Results Appendicular lean mass index was positively associated with total body and lumbar spine aBMD in both sexes ( p < 0.05), and with femoral neck aBMD in boys. Fat mass index was not significantly associated with aBMD at any site. No sex × body composition interactions were observed. The relative magnitude of lean and fat mass associations could not be statistically distinguished at lumbar spine and femoral neck ( p > 0.05). In the combined model, explanatory power for total body, lumbar spine and femoral neck was R 2 = 0.29, 0.18 and 0.05, respectively. Conclusion These findings indicate that lean mass is a group-level correlate of aBMD, but the strength and separability of lean and fat mass associations vary across skeletal sites, with limited ability to distinguish their relative contributions at clinically relevant regions.