Agreement and reproducibility of a portable electrical impedance myography device for body fat percentage estimation in normal weight men and women

Abstract

Abstract The aim of this study was to investigate the agreement and reproducibility of a portable electrical impedance myography device (EIM - SKULPT®) for body fat percentage (BF%) estimation in young adults. Sixty young adults volunteered for the study (women, n=30, 25.0±7.7 years; 21.5±1.9 kg/m2; and men, n=30, 21.6±6.3 years; 22.5±1.8 kg/m2). Participants underwent air displacement plethysmography (ADP) and EIM measurements for agreement analysis. EIM was performed three times on the same day for the within-day reproducibility analysis. Seven days later, 37 participants repeated the EIM measurements for the between-days reproducibility analysis. Comparisons of EIM and ADP methods, and EIM repeated measurements were performed with the paired T-test or one-way ANOVA repeated measures, the Bland-Altman plot, and simple linear regressions. BF% was higher (p<0.05) when estimated by EIM (19.91 ± 5.70 for men, and 30.77 ± 5.89 for women) compared to ADP (15.28 ± 5.66 for men, and 27.31 ± 5.98 for women). The Bland-Altman analysis presented a bias of 4.4% (95%CI=-3.4–12.2) and linear regression presented an R2=0.78. For between-days reproducibility, EIM means did not differ (25.33±7.69 and 24.94±8.30, p=0.890). Thus, while the EIM device exhibited high reproducibility of BF% estimates, caution should be exercised when comparing the results with other techniques for measuring BF%. The EIM device overestimated BF% compared to ADP. However, the EIM measurements presented very good within-day and between-days reproducibility and, thus, the EIM device can be used for longitudinal monitoring of BF%.