Effect of Race and Musculoskeletal Development on the Accuracy of Air Plethysmography


Political Science and International Affairs

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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 % FatAP and % Fat4C was similar for B (3.6 % body fat) and W (3.7 %). In addition, the density of the fat-free mass (Dffm) 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 % FatAP and % Fat4C 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 %f at by AP. Race-specific equations estimating % fat via densitometry (e.g., AP, HW) such as the Schutte are not justified, because Dffm 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.

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