Table 4. Hierarchical mixed-models with fixed and random effects for whole body, femoral neck and lumbar spine bone mineral content (BMC) development. Variable Whole body BMC Femoral neck BMC Lumbar spine BMC Fixed effects Constant -1112.2 ± 168.5 -1.1 ± 0.6 -31.6 ± 5.1 Age centered 18.7 ± 6.1 NS NS Height 12.8 ± 1.3 0.02 ± 0.01 0.30 ± 0.05 Body mass 16.9 ± 1.6 0.03 ± 0.01 0.27 ± 0.07 Leptin NS NS NS Adiponectin NS NS NS CMJ NS NS NS RBJ15s NS NS 0.10 ± 0.04 RG 71.9 ± 12.0 0.23 ± 0.11 1.39 ± 0.42 RG*Age centered 19.4 ± 6.09 0.9 ± 0.2 0.45 ± 0.22 Random effects Level 1 Constant 774.6 ± 101.2 0.02 ± 0.03 1.29 ± 0.19 Level 2 Constant Age centered Constant Age centered Constant Age centered Constant 4499.8 ± 970.4 120.6 ± 239.0 0.05 ± 0.02 0.003 ± 0.004 2.14 ± 0.91 0.14 ± 0.29 Age centered 120.6 ± 239.0 421.7 ± 105.5 0.003 ± 0.004 0.004 ± 0.002 0.14 ± 0.29 0.48 ± 0.15 Fixed effect values are estimates ± SEE (standard error of estimate) of bone mineral content (g). Random effects values are estimates. Age centered is age in years centered around 7 years of age (years). Height (cm), body mass (kg), leptin (ng/mL), adiponectin (μg/mL), CMJ (countermovement jump, cm), RBJ15s (rebound jumps for 15 s, cm). RG, rhythmic gymnasts. UC, untrained controls. All numerical values are reported as significant, p < 0.05. NS, not significant.