Factors influencing accuracy and reproducibility of body resistance measurements by foot-to-foot impedancemeters

Abstract

The electronics of a BodySignal V2 (Tefal, France) foot-to-foot impedancemeter (FFI) was modified to display the foot-to-foot resistance instead of body fat. This device was connected to electrodes of different sizes mounted on a podoscope permitting photographs of subjects feet soles and electrodes in order to calculate the contact area between feet and electrodes. The foot-to-foot resistance was found to decrease when the contact area of feet with current and voltage electrodes increased. It was also sensitive to feet displacement and a backward move of 5 cm increased the mean resistance by 37 Ω. The resistance reproducibility was tested by asking the subject to repeat measurements 10-times by stepping up and down from the podoscope. The mean SD of these tests was 0.88% of mean resistance, but it fell to 0.47% when feet position was guided and to 0.29% with transverse voltage electrodes. For good reproducibility, it is important that voltage electrodes be small and that the scale design facilitates a correct position of heels on these electrodes.

• Foot-to-foot impedancemeters
• optimization of plantar electrodes
• reproducibility and accuracy of body resistance measurements

Acknowledgements

The authors thank Tefal Company for its technical and financial support and the Algerian Government for the Scholarship of S. Bousbiat and I. Assadi. The impedance measurements made on volunteers from our university were approved by the Ethical committee of the Technological University of Compiegne and all subjects gave informed consent to the work.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.