EVALUATION OF A NEW AIR DISPLACEMENT PLETHYSMOGRAPH FOR MEASURING HUMAN-BODY COMPOSITION

A new air displacement plethysmograph, the BOD POD (R) (BP), was evalu ated in comparison to hydrostatic weighing (HW). Sixty-eight adult sub jects (26 F, 42 M) varying widely in age (range 20-56 yr), ethnicity, and fatness participated in this study. Same-day test-retest reliabili ty was assessed in a subsample of 16 subjects (9 F, 7 M) and validity was assessed in all subjects (N = 68). The test-retest coefficients of variation (CV) for %FAT measured by BP (%FAT(BP)) and HW (%FAT(HW)) w ere not significantly different (1.7% +/- 1.1% and 2.3% +/- 1.9% for B P and HW, respectively (mean +/- SD)), indicating excellent reliabilit y for both methods. Validity of percent fat measured by the BP (%FAT(B P)) was also excellent. The mean difference in %FAT (BP - HW) was -0.3 +/- 0.2 (SEM), with a 95% confidence interval of -0.6 to 0 %FAT. The regression equation (%FAT(HW) = 1.86 + 0.94 %FAT(BP); r(2) = 0.93, SEE = 1.81) was not significantly different from the line of identity (%F AT(HW) = %FAT(BP)), and did not differ by gender. These findings indic ate that the BOD POD is a highly reliable and valid method for determi ning %FAT in adult humans in comparison to HW. This new method has sev eral advantages over HW in that it is quick, relatively simple to oper ate and may be able to accommodate special populations such as the obe se, elderly, and disabled.