Title of article:

Bioimpedance analysis: Evaluation of leg-to-leg system based on pressure contact foot-pad electrodes

Authors: Nuñez C, Gallagher D, Visser M, Pe-Sunyer FX, Wang Z, Heymsfield SB.
Journal: Medicine and Science in Sports and Exercise. 1997.

Abstract

Objective: Bioimpedance analysis: evaluation of leg-to-leg system based on pressure contact foot-pad electrodes. Conventional single frequency bioempedance analysis (BIA) systems require technician placement of arm and leg gel electrodes, a suitable location for recumbent measurments, and a separate measurement of body weight. The aim of this study was to evaluate a new single frequency 50 kHz leg-to-leg bioimpedance analysis (BIA) system combined with a digital scale that emplys stainless stell pressure-contact foot pad electrodes for standing impedance and body weight measurements.
Methods: Healthy adults were evaluated for 1) electrode validity and 2) potential for body component estimation. Pressure-contact footpad electrode measured impedance was highly correlated with (n=9, r=0.99, p<0.001) impedance measured using conventional gel electrodes applied to the plantar surface of both lower extremities; mean (±SD) impedance impedance was systematically higher by about 15 ohms for pressure contact electrodes (526 ±56 ohms vs. 511 ±59 ohms; p<0.001). Second, the relationship between stature-adjusted leg-to-leg impedance ( H2/Z) measured by the new system and two body composition components (total body water by 3H2O dilution (n=144); and fat-free body mass, by underwater weighing and dual X-ray absorptiometry (n=231)) was modeled using multiple regression analysis.
Results: Correlation coefficients for H2/Z alone versus body composition components were lower for leg-to-leg BIA than for arm-to-leg BIA; correlation coefficients and SEEs became similar for the leg-to-leg and arm-to-leg BIA systems with addition of three covariates (age, gender, and waist/hip circumference ratio) to regression models. The leg-to-leg pressure contact electrode BIA system has overall performance characterists for impedance measurement and body composition analysis similar to conventional arm-to-leg gel electrode BIA and offers the advantage of increased speed and ease of measurement.

Comments and Key points

The leg-to-leg Bio-electrical impedance methods was superior to arm-to-leg methods. Using a Tanita body fat scale, gives equivalent results to Dual energy X-ray absorptiometry (DEXA), with no significant difference.

 

References

  1. http://www.tanita.com/professional/abstracts/abstract_main.html

Review & comments by Steven B. Halls, MD, Last edited 26-May-2008 Copyright.

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