Estimation of Total-Body Skeletal Muscle Mass in Children and Adolescents

PURPOSE: The estimation of total-body skeletal muscle mass (SMM) has been predicted in healthy adults using anthropometric measurements and urine creatinine excretion. SMM measurement is compulsory to evaluate exercise performance and the influence of physical training on muscle mass. However, there is a lack of information on children and adolescents when quantifying appendicular skeletal muscle mass. METHODS: Thirty-nine Caucasian children and adolescents (male and female, 7-16 yr old) and 20 adults (men and women, 20-24 yr old) were tested for total-body SMM using dual-energy x-ray absorptiometry measurement (DEXA), anthropometric measurements (ANTHR), and urine creatinine (UCrn) determination. Skinfold thickness and circumference were measured at mid-arm (CAG), mid-thigh (CTG), and mid-calf (CCG) and the skin-corrected circumferences (cm), together with height (Ht; m), age (yr), and sex (0 for female, 1 for male). The UCrn excretion (g.24 h(-1)) was also determined in all subjects. The ANTHR and UCrn measurements were then compared with DEXA as reference value. RESULTS: The multiple linear regression from anthropometric measurements gave the following equation to evaluate the total-body skeletal muscle mass (SMM) in children and adolescents: SMM (kg) = Ht x (0.0064 x CAG) + (0.0032 x CTG) + (0.0015 x CCG)(2) + (2.56 x sex) + (0.136 x age). The prediction of SMM from a 24-h urine collection was obtained with the following equation: SMM (kg) = (10.62 x Crn) + 6.63. The correlation coefficient (r(2)) was 0.966 and 0.710 for the anthropometric and creatinine methods, respectively (P < 0.001). CONCLUSION: Besides DEXA technique, the determination of total-body skeletal muscle mass in children and adolescents can be highly validated with satisfactory confidence by simple anthropometric measurements or 24-h urine creatinine excretion.