Limb muscle mass and phase angle asymmetry in 8-year-old children

Little is known about phase angle (PhA), a bioelectrical impedance analysis (BIA) indicator of cellular health, and muscle asymmetry in the limbs of children. The purpose of this study is to clarify PhA and muscle mass asymmetry in the limbs of children. We examined the muscle mass and PhA in the extremities of 1199 healthy 8-year-olds (604 males and 595 females) from large cohort study targeting children conducted in Japan. Muscle mass and PhA were measured in each limb by using a BIA device and the limb asymmetry of these body compositions was assessed. The muscle mass and PhA were significantly higher in the dominant upper limbs. In the lower limbs, muscle mass was greater on the right side in both sexes, whereas the PhA showed no significant asymmetry in males and was higher on the left side in females. The degree of asymmetry in the PhA was greater than that in muscle mass, especially in the upper limbs. These results provide a standard reference for asymmetry in muscle mass and PhA in the extremities for this age group. Further studies are needed to clarify the relationship between limb dominance and PhA.