TABLE 3.

Multiple linear regression models with pQCT measures of calf and thigh skeletal muscle fat content as dependent variables in girls.

Model 1	Physical activity			Ethnicity		Maturity		MCSA
	β	P	Variance	β	P	β	P	β	P
Calf muscle density	0.142	0.002	64.6%	−0.126	0.006	−0.001	0.985	−0.045	0.564
Thigh muscle density	0.153	<0.001	42.8%	−0.091	0.046	−0.205	0.002	0.213	0.002
Model 2	Physical activity			Ethnicity		Maturity		TBLM
	β	P	Variance	β	P	β	P	β	P
Calf muscle density	0.138	0.003	62.7%	−0.127	0.006	−0.034	0.734	0.003	0.976
Thigh muscle density	0.162	<0.001	61.2%	−0.089	0.053	−0.258	0.011	0.232	0.021

Standardized β coefficients and P values are presented for independent predictors of pQCT measures of calf and thigh skeletal muscle fat content (muscle density, mg/cm³). Of the total variance in calf and thigh skeletal muscle fat content explained by each full regression model, the percent explained by physical activity is presented. pQCT = peripheral quantitative computed tomography; MCSA = muscle cross-sectional area (mm²); TBLM = total body lean mass (kg).