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The purpose of this study was to examine the effect of three ventilation conditions (i.e., normal, regimented, and no-ventilation) on the reproducibility of bioimpedance scores in humans for the forearm and trunk segments. One hundred able-bodied North American men and women, from 18 to 71 years of age, volunteered as participants. The experimenters used a Xitron Bio-Impedance Analyzer System model 4200 instrument with Hydra software (Xitron Technologies, San Diego, California, USA) to collect bioimpedance data on extracellular fluid and intracellular fluid scores. The experimenters analyzed the data using the generalizability theory,with persons as the facet of differentiation and time as the facet of generalization. The major findings were (a) ventilation conditions did not have a significant impact on the reproducibility of the test scores, (b) the forearm segment produced consistently higher intracellular fluid generalizability coefficients across three ventilation conditions for both gender groups wh...

Generalizability theory was used to investigate the score consistency of observed extracellular fluid/intracellular fluid (ECF/ICF) ratio measurements for both the global and leg-segmental bio-impedance spectroscopy methods. The test instrument used was a Xitron Hydra ECF/ICF Bio-Impedance Analyzer System, model 4200 (Xitron Technologies, San Diego, CA). Fifty able-bodied American men (17 to 72 years) and 50 able-bodied American women (17 to 76 years) volunteered as experimental subjects. Xitron continuous global and leg-segmental ECF/ICF procedures for testing were followed for assessing subjects in both the standing erect and lying supine postures. A two-facet, person-by-trial, completely crossed design was used, and all facets were treated as random. Data were independently analyzed for each method, each body posture and each sex group. The major findings of this study were: (1) the leg-segmental method was superior in producing the higher G-coefficients when compared to the global method regardless of gender or posture; (2) the global method resulted in higher G-coefficients in males compared to females regardless of posture; (3) when the global method was used, the relative and absolute error variances were higher for females while the opposite trend was observed when the segmental method was used and (4) when using the global method, the precision of the ECF/ICF ratio scores in females could be increased by simply using the mean of several trials (e.g., by using the mean of 5, 10 or more test trials).

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 ICF. 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 ...

Generalizability theory was used to examine both the relative and absolute generalizability of the observed resistance, reactance, and phase angle measurements of total body bioelectrical impedance (Z) for men and women, using the Bioelectrical Impedance Analysis with modified electrode placement sites (Spectrum Lightweight Instrument; RJL Systems, Detroit, MI). Eighty men and 83 women from a military air force base volunteered as participants. RJL's rules for testing whole-body Z were followed with modification of the proximal electrode placement sites to the center of the antecubital space and popliteal fossa. The design was a 4-faceted crossed Person x Day x Occasion x Trial design treating all facets as random. Each participant was tested by 1 experienced tester on 2 days, 2 occasions, and 3 trials. Data were analyzed independently for each Z measurement anal each sex group. Overall, the modified electrode placement sites produced generalizability coefficients that were equal to or lower than the coef...

In this study, generalizability theory, an extension of classic true‐score reliability theory, was used to investigate the relative and absolute generalizability of the observed measurements of total body bioelectrical impedance (resistance, reactance, and phase angle) for men and women, using the bioelectrical impedance analysis (Spectrum Lightweight Instrument; RJL Systems, Detroit MI) for whole body composition. Eighty Alaskan military men (19 to 56 years old) and 83 Alaskan military women (19 to 54 years old) volunteered as subjects from Elmendorf Air Force Base, Anchorage, Alaska. The rules of RJL for testing whole body bioelectrical impedance were followed. The design was a four‐faceted cross: person by day by occasion by trial. All facets were treated as random. Each subject was tested by one tester on 2 days, 2 occasions, and 3 trials. Data were analyzed independently for each impedance measurement and each sex group. The analyses showed that the person by day interaction contributed a significant...

The aim of this study was to determine the score reproducibility of the observed extracellular-to-intracellular fluid (ECF/ICF) scores using generalizability theory across three ventilation conditions of the trunk and forearm segments. The test instrument employed was a Xitron Hydra ECF/ICF bioimpedance analyzer system Model 4200. Volunteer subjects were healthy North American males (n = 50) and females (n = 50), 18–71 years. Each segment was tested on a one-trial test, for each of the three ventilation conditions. The single trial was six continuous time measures, taken 5 s apart during a 30 s time period. The three ventilation conditions were the following: normal ventilation, regimented breathing and no ventilation. A two-facet, person-by-time, fully crossed design was used; all facets were treated as random. The ECF/ICF data for each segment were independently analyzed for each ventilation condition and each gender group. The findings were as follows. (1) The reproducibility of scores improved by using the forearm segment compared to the trunk segment, (2) breath holding improves the reproducibility of test scores compared to normal breathing on men's trunk scores, (3) breath holding was not superior to normal breathing on women's trunk scores.

The generalizability theory, an expansion of classic true-score reliability theory, was used to investigate the generalizability of observed segmental extracellular fluid (ECF) and intracellular fluid (ICF) distribution measurements. The test instrument was a Xitron Hydra ECF/ICF bioimpedance analysis system model 4200, Xitron Technologies, San Diego, CA. Fifty American healthy men (17-72 years) and 50 American healthy women (17-76 years) volunteered as participants. Xitron continuous segmental ECF-ICF procedures for testing leg segmental data were followed for testing participants in both the standing erect and lying supine postures. A two-facet, person-by-trial, completely crossed design was used. All facets were treated as random. During a one-day session each subject was tested involving 20 trials for the standing erect posture and 20 trials for the lying supine posture. Data on each fluid measurement, each body posture and each sex group were independently analysed. The analyses revealed that the trial factor accounted for less than 0.2% of the total variance for ECF and ICF scores. ECF and ICF generalizability coefficients for the segmental method were 0.99 or greater. In comparing ECF segmental to ECF global, results showed generalizability coefficients were similar. However, ICF segmental coefficients were larger than the coefficients produced by the global method. In conclusion, the segmental method appeared more reliable than the global method, under the conditions of this study.