Generalizability of bioimpedance spectroscopy measures

The generalizability of bioimpedance measures was studied for the lying and standing postures, using generalizability theory. The test instrument was a Xitron Hydra ECF/ICF Bio-Impedance Analyzer System Model 4200 (Xitron Technologies, San Diego, CA): 50 healthy men and 50 healthy women volunteered as participants. A 2-facet, person-by-trial, completely crossed design was used, and all facets were treated as random. Data on each body posture, each fluid measurement, and each sex group were independently analyzed. The lying-posture data showed that the trial facet accounted for less than 0.03% of the total variance for extracellular fluid (ECF) and intracellular fluid (ICF). The residual accounted for less than 0.02% of the total variance for ECF and for 9.5% for males and 13.6% for females of the total variance for ICE The standing-posture data showed that the trial facet accounted for less than 0.02% of the total variance for ECF and ICF. The residual accounted for less than 0.05% of the total variance for ECF and for 10.5% for males and 20.4% for females of the total variance for ICF. Overall, the lying posture produced more stable ECF and ICF measures, compared to the standing posture for male and female groups.