title: Reliability of air displacement plethysmography in a large, heterogeneous sample.
abstract: BACKGROUND
  Several studies have assessed the validity of air displacement plethysmography (ADP), but few have assessed the reliability of ADP using a large, heterogeneous sample.
  
  
  OBJECTIVE
  This study was conducted to determine the reliability of ADP using the Bod Pod in a large, heterogeneous sample.
  
  
  METHODS
  A total of 980 healthy men and women (30 +/- 15 yr, mean +/- SD) completed two body composition assessments separated by 15-30 min. All testing was done in accordance with the manufacturer's instructions.
  
  
  RESULTS
  A significant correlation (r = 0.992, P = 0.001) was found between body density (BD) 1 (1.046 +/- 0.001 kg.L(-1); mean +/- SEM) and BD 2 (1.046 +/- 0.001 kg.L(-1). A paired t-test revealed no significant difference between BD 1 and 2 (P = 0.935). The coefficient of variation (CV) for BD was 0.15%. A significant intraclass correlation coefficient (ICC) was found for BD (ICC = 0.996, P = 0.001), and the standard error of measurement (SEM) was 0.001 kg.L(-1). Body mass (BM) 1 and 2 were correlated significantly (r = 0.999, P = 0.001); however, a significant (P = 0.001) decrease was seen from BM 1 (75.510 +/- 0.461 kg) to BM 2 (75.497 +/- 0.461 kg). Body volume (BV) tended to decrease (P = 0.08) from BV 1 (69.900 +/- 0.449 L) to BV 2 (69.884 +/- 0.449 L).
  
  
  CONCLUSIONS
  ADP using the Bod Pod appears to assess BD reliably; however, the observed CV suggests that multiple trials are necessary to detect small treatment effects.
authors.affiliation: Department of Health Sciences, Gettysburg College, Gettysburg, PA 17325, USA. enoreen@gettysburg.edu
authors.forename: Eric E
authors.initials: EE
authors.lastname: Noreen
authors.forename: Peter W R
authors.initials: PW
authors.lastname: Lemon
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D005260:Female; D006801:Humans; D008297:Male; D010991:Plethysmography / Q000379:methods*; D015203:Reproducibility of Results