[A method for analysis of muscle activity during electric stimulation]. / Eine Methode zur Analyse der Muskelaktivität unter elektrischer Reizung.

The measurement of the surface-EMG during electrical stimulation requires the suppression of the stimulus pulse close to the source. This is necessary because of the discharge currents spreading within the human body caused by the stimulation pulse and the drift effects at the electrodes distorting the EMG-signal. A measurement-system will be presented, which splits the EMG in a detection and a processing path. A special converter keeps the base line at zero level. The detection path sets the gain of the recording amplifier and identifies the stimulation pulse to control its suppression. The processing of the EMG is conducted in the main path way. By these means the EMG including M-wave is undistorted and unbiased presented. The results will be discussed taking the physiology relevance into account.

[Bipolar , active electrode for 4-channel recording of dynamic surface EMG during electric stimulation]. / Eine bipolare, aktive Elektrode zur Vielkanalableitung des dynamischen EMGS während Elektrostimulation.

In this paper we present an electrode for measuring the surface electromyogram (EMG) that combines high quality of signal recording with the ease of use in clinical routine. Additional requirements have been the use of the electrode in combination with electrical stimulation and under dynamic conditions like walking. Special focus was put on the minimization of movement artifacts by integration of a dual impedance transformer (active electrode) and by a self-adjusting fixation of the two contacts of the electrode via proprietary springs. An elaborate preparation of the skin is not necessary due to a very high input impedance of the amplifier. A special circuit for overvoltage protection makes the electrode suitable for use in the presence of high voltage stimulation pulses without the risk of destroying the FET-input stages.