Use of air displacement plethysmography in the determination of percentage of fat mass in African American children

The purpose of this study was to determine the ability of air displacement plethysmography (ADP) to estimate percentage of fat mass (%FM) in African American children. %FM was determined in 21 boys and 13 girls (11.0 +/- 1.4 y, 18.6 +/- 4.2 kg/m(2) [mean +/- SD]) by ADP (using six published densitometric equations) and dual-energy x-ray absorptiometry (DXA). Measures were done within 2 h of one another, in random order. Regardless of equation, %FM(ADP) was significantly correlated with %FM(DXA) (R(2) = 0.67-0.71, all p < 0.001). %FM(ADP) using the equation of Siri (%FM(ADP-Siri) 20.3 +/- 9.0) agreed most closely with %FM(DXA) (20.0 +/- 10.2, difference p = 0.729). Together, surface area artifact and bone mineral content per unit of bone-free fat-free mass accounted for 29% of the variance in the residual between methods. The correlation between %FM(ADP-Siri) and %FM(DXA) was not significant for those