Lack ok congruence in single and multifrbquhncy bio-impedance rstimates of body composition

By using phase sensitive, multifrequency electronics, and the Cole-Cole modeling approach the bio-impedance spectroscopy technique has the theoretical capability to provide more accurate estimates of body composition parameters than those derived from single frequency technology. We used single (Valhalla 1990B)and multifrequency (Xilron 4000B) bio-impedance analysis to derive total body water (IB W). percent body fat (%B!;), and fatfree mass (FFM) in a sample of I7 women Comparisons of %BF from each bio-impedance technique with °/uBF from undenvater weighing (UWW) were also made The subjects were 17 healthy, weight-stable females, \vith an average age ol 2:S._! 4.2 y. height of I62i6.0 cm, and weight of 70.112 1.9 kg; °/oBF from UW\V' was 28 6- U.I. Standard protocols und tetrapolar electrode placement for whole-body analysis were used Although one-way ANOVA revealed no significant differences (Table I) among the three estimates of °'oBF. the mean value obtained from the single frequency technique was closer to the criterion value from Table I. Body Composition Estimates Using single and Multiple Frequency Impedance Analysis UWW. Furthermore. the indicate no congruence between the two impedance techniques on any of the body composition estimates. Method %BF FF-M (kg) TBV(L) Single Frequency 27.5 ± 10.5b 48.5 ± 8.7a 36.3 ± 4.9a Multiple Freguency 36.1 ± 10.8a 42.8 ± 6.5b 61.6 ± 4.8b Underwater Weighing 3 28.6 ± 14.1 1 Values arc means ± SD ²n = 17 ³n = 15 b Means within il ailumn with liillerait letter superscripts are significantly different (P<0.05) techniques provide significantly different estimates of %BF, TBW. and FFM. The greatest divergence appears to he in the overestimation of %BF usina the multifrequency technique m this population.