title: Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets.
abstract: BACKGROUND
  Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population.
  
  
  METHODS
  A total of 396 males, Brazilian Army cadets, aged 17-24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student's t-test (for paired sample), linear regression analysis, and Bland-Altman method were used to test the validity of the BIA equations.
  
  
  RESULTS
  Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05) and large limits of agreement by Bland-Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values.
  
  
  CONCLUSIONS
  Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. raqueldlanger@gmail.com.
authors.forename: Raquel D
authors.initials: RD
authors.lastname: Langer
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. borgesedfisica@gmail.com.
authors.forename: Juliano H
authors.initials: JH
authors.lastname: Borges
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. pascoawaf@bol.com.br.
authors.forename: Mauro A
authors.initials: MA
authors.lastname: Pascoa
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. vxcirolini@hotmail.com.
authors.forename: Vagner X
authors.initials: VX
authors.lastname: Cirolini
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. gilguer@fcm.unicamp.br.
authors.forename: Gil
authors.initials: G
authors.lastname: Guerra-Júnior
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences, University of Campinas (UNICAMP), Campinas-SP 13083-887, Brazil. emaildozeique@gmail.com.
authors.forename: Ezequiel M
authors.initials: EM
authors.lastname: Gonçalves
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000367:Age Factors; D001823:Body Composition; D001938:Brazil; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D006801:Humans; D016014:Linear Models; D008297:Male; D008889:Military Personnel; D008954:Models, Biological; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012737:Sex Factors; D055815:Young Adult
keywords: body composition; dual-energy X-ray absorptiometry; predictive equations