Accuracy of body composition prediction equations by bioelectrical impedance method and skinfold thickness method-from the viewpoint of the longitudinal alterations in body composition of schoolchildren / 体力科学

ABSTRACT

A study was conducted to determine the accuracy of body composition prediction equations using the bioelectrical impedance (BI) method and skinfold thickness (ST) method for predicting longitudinal alterations in the body composition of schoolchildren. Seventeen healthy junior high school boys, aged 12 to 13 yr, participated in the study. Body density (Db) was determined by underwater weighing (UW) . Impedance was measured using a portable four-terminal impedance plethysmograph (800 μA, 50 kHz ; Selco, SIF-891) . Db values by the BI method were estimated from the equations developed for schoolchildren by Watanabe et al. (1993) and Kim et al. (1993) . Db by the ST method was estimated from the equations developed for schoolchildren by Nagamine et al. (1974) and Watanabe et al. (1993), using the sum of skinfold thickness at the triceps and subscapular area. Skinfold thickness was measured on the right side of the body with an Eiken-type skinfold caliper. The changes in Db and body fat measured by UW were small every year. The fat free mass (FFM) measured by UW increased significantly every year. The body composition (average Db, body fat and FFM) values estimated by the BI and ST methods showed no significant differences against average UW values. However, these average values estimated using the equation of Nagamine et al. (1974) were significantly different from the average UW values. The absolute amount of change in FFM (&Delta; FFM) estimated from BI and ST methods were correlated significantly with absolute amount of change in FFM (&Delta; FFM) determined by UW. In particular, the accuracy of body composition prediction equations for the BI method (r<SUP>2</SUP>= 0.81 for Watanabe et al., r<SUP>2</SUP> = 0.77 for Kim et al.) was higher than that of body composition prediction equations for the ST method (r<SUP>2</SUP>=0.41 for Nagamine et al., r<SUP>2</SUP>= 0.55 for Watanabe et al) . The findings of this study suggest that the body composition prediction equations based on the BI method are useful for valid assessment of longitudinal alterations in the body composition of schoolchildren.