Growth and gender differences of lower limb muscle thickness in children aged between 3 and 8 years old

Abstract

The purpose of this study was to compare age and gender differences of lower limb muscle thickness among healthy young children. Five hundred and sixty-one healthy young children aged 3 to 8 years old (284 boys and 277 girls) participated in this study. Anterior thigh, posterior thigh, and calf muscle thicknesses (MTa, MTp, MC) were determined using a B-mode ultrasound. The thickness of each muscle increased significantly as age increased, except in the MTa in the 5-year-old boys' group. A significantly main effect was found in MTa, and there was a higher value in girls than boys, except in the 4-year-old group. A significant age × gender interaction was also observed in MTa, with higher values found in boys than girls, except in the 3- and 5-year-old groups. There was no significant gender different in MC. In addition to the Mt/Tmt ratio, the ratio of each muscle thickness to the total amount of MTa, MTp, and MC was calculated. As a result, in girls, the Mt/Tmt ratio remained constant as age increased in all muscles. On the other hand, in boys, MTa decreased and MTp increased as age increased. From these results, it was suggested that gender differences exist in lower limb muscles thickness among healthy young children aged between 3 and 8 years old. It was also suggested that the muscle development of MTa and MTp was different in boys, while lower limb muscle development in girls stayed constant.