title: Body composition assessment in overweight women: validation of air displacement plethysmography.
abstract: OBJECTIVE
  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 ≥ 25·0 kg m(2) ).
  
  
  METHODS
  Twenty-four overweight and obese women (Mean ± SD; Age: 36·6 ± 12·0 years; Height: 166·4 ± 5·8 cm; Weight: 86·5 ± 14·2 kg; Body Fat: 38·5 ± 3·7%; BMI: 31·3 ± 5·5 kg m(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.
  
  
  RESULTS
  Validity data comparing ADP and DXA demonstrated no significant difference in FM (ADP-DXA FM = 0·99 kg; P = 0·113), FFM (0·98 kg; 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Exercise and Sport Science, Applied Physiology Laboratory, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Hailee L
authors.initials: HL
authors.lastname: Wingfield
authors.forename: Abbie E
authors.initials: AE
authors.lastname: Smith-Ryan
authors.forename: Mary N
authors.initials: MN
authors.lastname: Woessner
authors.forename: Malia N
authors.initials: MN
authors.lastname: Melvin
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Fultz
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Graff
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity; D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition; D015519:Bone Density; D005260:Female; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging / Q000503:physiopathology*; D050177:Overweight / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010991:Plethysmography / Q000379:methods*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult
keywords: dual energy x-ray absorptiometry; fat-free mass; percent body fat; sensitivity; sex