The potential of classic and specific bioelectrical impedance vector analysis for the assessment of sarcopenia and sarcopenic obesity

Abstract

Purpose: The aim of this paper is to investigate whether bioelectrical impedance vector analysis (BIVA) can be a suitable technique for the assessment of sarcopenia. We also investigate the potential use of specific BIVA as an indicator of sarcopenic obesity.

Subjects and methods: The sample comprised 207 free-living elderly individuals of both sexes, aged 65 to 93 years. Anthropometric and bioelectrical measurements were taken according to standard criteria. The "classic" and "specific" BIVA procedures, which respectively correct bioelectrical values for body height and body geometry, were used. Dual energy X-ray absorptiometry (DXA) was used as the reference method for identifying sarcopenic and obese sarcopenic individuals. Bioelectrical and DXA values were compared using Student's t-test and Hotelling's T(2) test, as well as Pearson's correlation coefficient.

Results: According to classic BIVA, sarcopenic individuals of both sexes showed higher values of resistance/height (R/H; p < 0.01) and impedance/height (Z/H; p < 0.01), and a lower phase angle (p < 0.01). Similarly, specific BIVA showed significant differences between sarcopenic and nonsarcopenic individuals (men: T(2) = 15.7, p < 0.01; women: T(2) = 10.7, p < 0.01), with the sarcopenic groups showing a lower specific reactance and phase angle. Phase angle was positively correlated with the skeletal muscle mass index (men: r = 0.52, p < 0.01; women: r = 0.31, p < 0.01). Specific BIVA also recognized bioelectrical differences between sarcopenic and sarcopenic obese men (T(2) = 13.4, p < 0.01), mainly due to the higher values of specific R in sarcopenic obese individuals.

Conclusion: BIVA detected muscle-mass variations in sarcopenic individuals, and specific BIVA was able to discriminate sarcopenic individuals from sarcopenic obese individuals. These procedures are promising tools for screening for presarcopenia, sarcopenia, and sarcopenic obesity in routine practice.

Keywords: BIVA; DXA; aging; body composition.

Figure 1

Mean impedance vectors and confidence ellipses from groups with and without sarcopenia. Abbreviations: D, Mahalanobis distance; H, height; R, resistance; Xc, reactance.

Figure 2

Mean impedance vectors and confidence ellipses from sarcopenic men with FM% higher or lower than the median value of the sex-specific whole sample. (A) Classic BIVA; (B) specific BIVA. Abbreviations: D, Mahalanobis distance; FM, fat mass; H, height; R, resistance; sp, specific; Xc, reactance.

Figure 3

The individual specific vectors of sarcopenic men plotted on the sex-specific bivariate tolerance ellipse. Notes: White dots indicate sarcopenic nonobese men; black dots indicate sarcopenic obese men. Abbreviations: R, resistance; sp, specific; Xc, reactance.