Reference values of skeletal muscle mass indices in Chinese children aged 6-9 years in Guangzhou

Objective To establish the reference values of skeletal muscle indices of children aged 6-9 in Guangzhou,China,and to provide reference for their muscule development.Methods A total of 456 children aged 6-9 years old were enrolled in urban area of Guangzhou.Dual-energy X-ray absorptiometry (DXA) was applied to determine whole body muscle mass (WBM),arms muscle mass,legs muscle mass,appendicular skeletal muscle mass(ASM).Weight and height were measured.BMI and skeletal muscle mass indices including ASM/height,ASM/weight,and ASM/BMI were calculated.LMS regression analysis was used to construct age-and gender-specific smooth percentile curve of the above-mentioned indices.Results All of the skeletal muscle mass measurements increased significantly with age in both genders.Apart from the indexes of ASM,ASM/weight,ASM/BMI in the group of 6 years old and ASM/weight,ASM/BMI in the group of 9 years old,the measures of boys were generally significantly higher than those of girls(P< 0.05).Conclusion The reference values for skeletal muscle mass in children aged 6-9 years in Guangzhou can provide a correct reference for evaluating children's muscle development.