title: Validity of Skinfold-Based Measures for Tracking Changes in Body Composition in Professional Rugby League Players.
abstract: High levels of lean mass are important in collision-based sports for the development of strength and power, which may also assist during contact situations. While skinfold-based measures have been shown to be appropriate for cross-sectional assessments of body composition, their utility in tracking changes in lean mass is less clear.
  
  
  OBJECTIVE
  To determine the most effective method of quantifying changes in lean mass in rugby league athletes.
  
  
  METHODS
  Body composition of 21 professional rugby league players was assessed on 2 or 3 occasions separated by ≥6 wk, including bioelectrical impedance analysis (BIA), lean-mass index (LMI), and a skinfold-based prediction equation (SkF). Dual-X-ray absorptiometry provided a criterion measure of fat-free mass (FFM). Correlation coefficients (r) and standard errors of the estimate (SEE) were used as measures of validity for the estimates.
  
  
  RESULTS
  All 3 practical estimates exhibited strong validity for cross-sectional assessments of FFM (r > .9, P < .001). The correlation between change scores was stronger for the LMI (r = .69, SEE 1.3 kg) and the SkF method (r = .66, SEE = 1.4 kg) than for BIA (r = .50, SEE = 1.6 kg).
  
  
  CONCLUSIONS
  The LMI is probably as accurate in predicting changes in FFM as SkF and very likely to be more appropriate than BIA. The LMI offers an adequate, practical alternative for assessing in FFM among rugby league athletes.
authors.affiliation: Applied Sport Science and Exercise Testing Laboratory, University of Newcastle, Ourimbah, NSW, Australia.
authors.forename: Jace A
authors.initials: JA
authors.lastname: Delaney
authors.forename: Heidi R
authors.initials: HR
authors.lastname: Thornton
authors.forename: Tannath J
authors.initials: TJ
authors.lastname: Scott
authors.forename: David A
authors.initials: DA
authors.lastname: Ballard
authors.forename: Grant M
authors.initials: GM
authors.lastname: Duthie
authors.forename: Lisa G
authors.initials: LG
authors.lastname: Wood
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Dascombe
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000886:Anthropometry; D056352:Athletes; D001823:Body Composition; D017097:Electric Impedance; D005538:Football / Q000502:physiology*; D006801:Humans; D008297:Male; D012885:Skinfold Thickness; D055815:Young Adult