The estimation model for appendicular skeletal muscle mass in US children and adolescents

Adult guidelines recommend height-adjusted appendicular skeletal muscle mass (ASM) as the evaluation index for muscle mass.

To develop and validate predictive equations for ASM in children and adolescents.

A cross-sectional secondary analysis of National Health and Nutritional Examination Surveys (NHANES) data was conducted on United States children and adolescents aged 8-19 years. ASM was assessed by the sum of the lean mass of the upper and lower limbs. Multiple linear regression analyses were performed to estimate ASM using age, race and anthropometric variables [standing height (Ht), weight (Wt), arm circumference (AC) and waist circumference (WC)] with different combinations.

Using multiple linear regression analyses, two predictive equations were generated. Equation = 0.502 + 0.388 * Wt (kg) - 0.234 * WC (cm) + 0.217 * Age (y) + 1.055 * Race (non-black = 0, black = 1) + 0.066 * Ht (cm) was for boys (adjusted R² 0.965 and standard error of the estimate (SEE) 1.42 kg). Equation = -2.868 + 0.261 * Wt (kg) - 0.092 * WC (cm) + 1.357 * Race (non-black = 0, black = 1) + 0.066 * Ht (cm) was for girls (adjusted R² 0.938 and SEE 1.18 kg).

The two anthropometric prediction equations presented for ASM are simple and accurate tools for predicting ASM in US children and adolescents.