Effect of race and musculoskeletal development on the accuracy of air plethysmography

Purpose: The purpose of this study was to determine the effect of race and musculoskeletal development on the accuracy of estimates of body fatness (%fat) via air displacement plethysmography (AP). Methods: Estimates of %fat were made via AP, hydrostatic weighing (HW), dual-energy x-ray absorptiometry (DXA), and the criterion, a four-component model (4C) in 64 black (B) and white (W) men, who were either resistance trained (RT) or served as controls (C). Results: Based on a three-way ANOVA, there were no statistically significant three-way or race X musculoskeletal development interactions. There was no main effect of race on the validity of estimating %fat by AP; the mean bias between %Fat(AP) and %Fat(4C) was similar for B (3.6% body fat) and W (3.7%). In addition, the density of the fat-free mass (D-ffm) for B (1.098 +/- 0.002 g(.)mL(-1)) was not different than 1.10 g(.)mL(-1). There was a significant effect of musculoskeletal development on the validity of the estimation of %fat from AP; the mean difference in %fat between %Fat(AP) and %Fat(4C) was less in RT (1,5% body fat) than in C (5.3%), but a large SEE of 5.5% was observed for RT. A significant (P < 0.05) correlation was found between the mean bias between methods and body volume (-0.44) and mesomorphy (-0.55). Conclusions: Race does not affect the accuracy of estimating %fat by AP. Race-specific equations estimating %fat via densitometry (e.g., AP, HW) such as the Schutte are not justified, because D-ffm is not greater than 1.10 g(.)mL(-1). Estimation of %fat via AP is more accurate in larger individuals with high musculoskeletal development as a group, but individual results are highly variable.