title: Measurement of body composition in 8-10-year-old African-American girls: a comparison of dual-energy X-ray absorptiometry and foot-to-foot bioimpedance methods.
abstract: OBJECTIVE
  The purpose of this study was to evaluate body composition outcomes of foot-to-foot (FF) bioelectrical impedance (BIA) and dual-energy x-ray (DEXA) in 8 to 10-year-old African-American girls and, if different, to develop and cross-validate specific BIA prediction equations for this at-risk group.
  
  
  METHODS
  DEXA and FF-BIA body composition outcomes were analyzed in 183, 8-10-year-old African-American girls from the Memphis site of the Girls health Enrichment Multi-site Study (GEMS).
  
  
  RESULTS
  Mean body composition outcomes by FF-BIA and DEXA were significantly different (p<0.0001); therefore, population-specific equations were developed and cross-validated using split-sample, cross-validation methods. When equations were used, BIA and DEXA outcomes were significantly correlated (percent body fat [r=0.931], fat mass [r=0.985], and fat-free mass [r=0.944]). Mean predicted BIA measurements for body fat, fat mass, and fat-free mass were essentially equal to their counterpart DEXA measurements (t[182]=- 0.013, p = 0.897, t[182]=- 0.06, p=0.956, and t[182]=- 0.26, p=0.792, respectively). The Bland-Altman analysis revealed a significant slope for percent fat (p=0.009) and slopes approaching significance for fat mass (p=0.07) and fat-free mass (p=0.06).
  
  
  CONCLUSIONS
  Although FF-BIA and DEXA are not directly interchangeable in young African-American girls, these equations accurately estimated average percent fat, fat mass, and fat-free mass of the cross-validation sample of African-American girls. However, the application of this equation may result in potential underestimation or overestimation of fat with respect to DEXA measures in some populations.
authors.affiliation: Department of Health and Sport Sciences, University of Memphis, Memphis, TN 38152, USA. bmcclnhn@memphis.edu
authors.forename: Barbara S
authors.initials: BS
authors.lastname: McClanahan
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Stockton
authors.forename: Jennifer Q
authors.initials: JQ
authors.lastname: Lanctot
authors.forename: George
authors.initials: G
authors.lastname: Relyea
authors.forename: Robert C
authors.initials: RC
authors.lastname: Klesges
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Slawson
authors.forename: Leslie P
authors.initials: LP
authors.lastname: Schilling
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000208:ethnology; D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D017097:Electric Impedance; D005260:Female; D005528:Foot; D006801:Humans; D009765:Obesity / Q000175:diagnosis* / Q000208:ethnology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D012044:Regression Analysis; D015203:Reproducibility of Results; D013714:Tennessee; D001741:Black or African American