title: Validation of near-infrared interactance and skinfold methods for estimating body composition of American Indian women.
abstract: OBJECTIVE
  This study tested the predictive accuracy of the Jackson et al. skinfold (SKF) equations (sigma7SKF and sigma3SKF), a multi-site near-infrared interactance (NIR) prediction equation, and the Futrex-5000 NMR equation in estimating body composition of American Indian women (N = 151, aged 18-60 yr).
  
  
  METHODS
  Criterion body density (Db) was obtained from hydrodensitometry at residual lung volume.
  
  
  RESULTS
  Sigma7SKF significantly underestimated Db (P < 0.05). Sigma3SKF and Heyward's NIR equations significantly overestimated Db (P < 0.05). The Futrex-5000 NIR equation significantly underestimated percent of body fat (%BF) (P < 0.05). Prediction errors for SKF and multi-site NIR exceeded 0.0080 g x cc(-1). The SEE for Futrex-5000 was 5.5%BF. Thus, ethnic-specific SKF and NIR equations were developed. For the SKF model, the sigma3SKF (triceps, axilla, and suprailium) and age explained 67.3% of the variance in Db:Db = 1.06198316 -0.00038496(sigma3SKF) -0.00020362(age). Cross-validation analysis yielded r = 0.88, SEE = 0.0068 g x cc(-1), E = 0.0070 g x cc(-1), and no significant difference between predicted and criterion Db. For the NIR model, the hip circumference, sigma2AdeltaOD2 (biceps and chest), FIT index, age, and height explained 73.9% of the variance in Db:Db = 1.0707606 -0.0009865(hip circumference) -0.0369861(sigma2deltaOD2) + 0.0004167(height) + 0.0000866(FIT index) -0.0001894(age). Cross-validation yielded r = 0.85, SEE = 0.0076 g x cc(-1), E = 0.0079 g x cc(-1), and a small, but significant, difference between predicted and criterion Db.
  
  
  CONCLUSIONS
  We recommend using the ethnic-specific SKF and NIR equations developed in this study to estimate Db of American Indian women.
authors.affiliation: Center for Exercise and Applied Human Physiology and the Clinical Nutrition Laboratory, University of New Mexico, Albuquerque 87131, USA.
authors.forename: V L
authors.initials: VL
authors.lastname: Hicks
authors.forename: L M
authors.initials: LM
authors.lastname: Stolarczyk
authors.forename: V H
authors.initials: VH
authors.lastname: Heyward
authors.forename: R N
authors.initials: RN
authors.lastname: Baumgartner
mesh_terms: D015502:Absorptiometry, Photon / Q000592:standards*; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007198:Indians, North American; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis; D012680:Sensitivity and Specificity; D012885:Skinfold Thickness; D016387:Women's Health