Validity of near-infrared interactance for estimating relative body fat in female high school gymnasts

D. B. Smith, G. O. Johnson, J. R. Stout, T. J. Housh, D. J. Housh, T. K. Evetovich

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The present investigation examined the validity of near-infrared interactance (NIR) estimates of relative body fat (% fat) from the Futrex-5000 (F5000), Futrex-5000 A (F5000 A), and Futrex-1000 (Fl000) instruments. Ninety-eight female high school gymnasts (X̄ age ± SD = 15.7 ± 1.2 yr) participated in this investigation. Subsamples were used to cross-validate the F5000 (n = 52), F5000 A (n = 46), and F1000 (n = 89) instruments. The NIR % fat estimates were validated against criterion % fat from underwater weighing (UWW) using the adult conversion constants of Brozek et al. (6) (UWWB) and the female age-specific constants of Lohman (23) (UWWL). The cross-validation statistical analysis included examination of the constant error (CE), standard error of estimate (SEE), r, and total error (TE). In addition, full-model multiple regression analyses were used to predict UWWB or UWWL from body weight (BW) and height (HT). BW and HT were correlated with % fat at R = 0.65-0.70, while the validity coefficients for the NIR instruments ranged from r=0.40-0.78. The F5000 resulted in nonsignificant CE values (- 0.3% fat vs UWWB and 1.5 % fat vs UWWL; p > 0.008) as well as the lowest TE values (TE = 3.1% fat vs UWWB and 4.0% fat vs UWWL). All other NIR estimates of % fat resulted in TE values ≤ 6.3% fat. In addition, for all NIR instruments there were negative correlations for the plots of the CE versus the mean of predicted and criterion (UWWB and UWWL)% fat. Therefore, the present findings indicated that the F5000 provided more accurate estimates of % fat than the F5000 A or F1000 instruments, but may underestimate the desired minimal body weight for female gymnasts at the low end of the % fat distribution.

Original languageEnglish (US)
Pages (from-to)531-537
Number of pages7
JournalInternational Journal of Sports Medicine
Issue number7
StatePublished - 1997


  • Body composition
  • Gymnasts
  • Near-infrared interactance

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Orthopedics and Sports Medicine


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