Body composition assessment in overweight women: validation of air displacement plethysmography

Abstract

The purpose of this study was to evaluate the validity and reliability of air displacement plethysmography (ADP) compared to a dual energy x-ray absorptiometry (DXA) criterion for body composition measurement in overweight and obese women (BMI≥25·0kgm(2) ). Twenty-four overweight and obese women (Mean±SD; Age: 36·6±12·0years; Height: 166·4±5·8cm; Weight: 86·5±14·2kg; Body Fat: 38·5±3·7%; BMI: 31·3±5·5kgm(2) ) were tested after an 8-h fast. Fat mass (FM), fat-free mass (FFM) and percent body fat (%BF) were measured by ADP and compared to values determined by the DXA criterion. FFM from DXA was calculated as lean mass plus bone mineral content. A paired samples t-test was used to test for significant differences in the body composition variables between methods. A one-way ANOVA along with intraclass correlation coefficient (ICC), SEM,%SEM and MD was used to represent reliability. Validity data comparing ADP and DXA demonstrated no significant difference in FM (ADP-DXA FM=0·99kg; P=0·113), FFM (0·98kg; P=0·115) and %BF (1·56%; P=0·540). Reliability data for ADP between the first and second trials showed no significant difference in FM (P=0·168; ICC=0·994; SEM=0·668), FFM (P=0·058; ICC=0·973; SEM=0·892) or %BF (P=0·121; ICC=0·971; SEM=0·813). For overweight and obese women, ADP was found to be a valid measure of FM, FFM and %BF when compared with DXA. The reliability of ADP was supported for all body composition variables.