Bioelectrical impedance analysis (BIA) and skinfold thickness (SF) (triceps and subscapular) methods were applied to 436 Japanese school children (228 boys and 208 girls) aged from 9 to 11 years with a one-year follow-up to determine changes in body composition. By BIA oneyear increment (Δ) of lean body mass (LBM) for boys increased significantly (p<0.01) and Δ LBM was almost equivalent to that for Δ weight (Wt). Δ Wt and Δ fat mass (FM) between the age 10 (from ages 10 to 11) and age 11 (from ages 11 to 12) groups in girls achieved statistical significance (p<0.01 and p<0.001, respectively) and Δ Wt was almost completely comprised of the Δ FM in these age groups. Δ FM in die age 11 group for girls was statistically higher than that in the age 10 group, and this obvious increase of FM in the age 11 group was presumed to be die effect of menses in consideration of die maximum oneyear increment of Ht (Δ Ht) in die age 10 group.
These results of the assessment of body composition by BIA supported those of previous reports, and therefore BIA can be considered as a useful mediod to estimate changes in body composition of school children because it is simple and non-invasive and can be performed rapidly.