Skeletal muscle mass reference curves for children and adolescents

摘要

What is already known about this subject Skeletal muscle is considered a major site of insulin-mediated glucose disposal and is thus a key tissue in whole-body glucose homeostasis. Low muscle mass and fitness is associated with metabolic risk and muscular strength is positively related to higher insulin sensitivity in children and adolescents. The use of skeletal muscle mass measurement in surveillance has been constrained by the absence of normative data that identifies individuals across the age spectrum with high or low amount of skeletal muscle. What this study adds This study demonstrates that compartmental bioimpedance analysis provides a simple and non-invasive method for assessing muscle-to-fat ratios in children. Centile curves for appendicular skeletal muscle mass and fat-free mass have been added to the suite of charts available for assessing growth and body composition across childhood and adolescence. Muscle-to-fat ratio has been described and shows potential as an improved measure of metabolic risk. Background Skeletal muscle is key to motor development and represents a major metabolic end organ that aids glycaemic regulation. Objectives To create gender-specific reference curves for fat-free mass (FFM) and appendicular (limb) skeletal muscle mass (SMMa) in children and adolescents. To examine the muscle-to-fat ratio in relation to body mass index (BMI) for age and gender. Methods Body composition was measured by segmental bioelectrical impedance (BIA, Tanita BC418) in 1985 Caucasian children aged 5-18.8 years. Skeletal muscle mass data from the four limbs were used to derive smoothed centile curves and the muscle-to-fat ratio. Results The centile curves illustrate the developmental patterns of %FFM and SMMa. While the %FFM curves differ markedly between boys and girls, the SMMa (kg), %SMMa and %SMMa/FFM show some similarities in shape and variance, together with some gender-specific characteristics. Existing BMI curves do not reveal these gender differences. Muscle-to-fat ratio showed a very wide range with means differing between boys and girls and across fifths of BMI z-score. Conclusions BIA assessment of %FFM and SMMa represents a significant advance in nutritional assessment since these body composition components are associated with metabolic health. Muscle-to-fat ratio has the potential to provide a better index of future metabolic health.