[Temperature dependent alterations of the surface-EMG and ECG: an investigation of the electrical transfer characteristics of the human skin (author's transl)].

The influence of local heating of the skin on the integrated EMG (registered with surface and subcutaneous electrodes), the amplitude of the ECG, the skin blood flow, the electrode impedance, the electrode-to-skin impedance, and the tissue impedance is investigated. Except for the increasing skin blood flow each of the variables exhibits a significant reduction with an increase in skin temperature. From these results the existence of two mechanisms is deduced mediating thermal influence on bioelectric signals picked up by surface electrodes: 1. An alteration of the signal source. 2. An alteration of the electric transfer characteristics of the tissue between signal source and electrode. Especially in quantitative surface electromyography the temperature dependence of the signal can be a source of error.