Validation of the Futrex-5000 Near-Infrared Spectrophotometer Analyzer for Assessment of Body Composition

Abstract

In recent years the clinical market for new systems of body composition analysis has significantly expanded, but definitive research is lacking. The purpose of this study was to investigate the reliability and validity of the Futrex-5000 near infrared (NIR) device for determining percent body fat (%BF) and fat-free mass (FFM) in 34 adult caucasian men (age range 28–53 years; weight range 63–131 kg). A repeated measures design was used, including within- and between-day NIR test-retest for reliability analysis and comparisons to hydrostatic weighing (HYDRO) for cross validation. Statistical analysis revealed small between trial NIR mean differences (<.5% BF and <.5 kg FFM), high intraclass correlation coefficients (ICCs > 0.90), nonsignificant HYDRO vs. NIR mean contrasts (<1.0% BF and <.9 kg FFM), significant between-method Pearson correlation coefficients (% BF r = 33, FFM (kg) r = .86), and total prediction errors (E) that were similar to the standard errors of estimate (%BF SEE = 4.2 vs. E = 4.4% and FFM SEE = 3.8 vs. E = 3.9 kg). In general, the results support good measurement reliability but borderline acceptability for measurement accuracy. Additional research with refinement of the manufacturer's current prediction equation is recommended prior to the adoption of the NIR device for widespread clinical application.