Averaged (rms) surface EMG in testing back function
Sihvonen, T.; Partanen, J.; Hänninen, O.
Electromyography and Clinical Neurophysiology 28(6): 335-339
1988
ISSN/ISBN: 0301-150X PMID: 3248556 Document Number: 310235
Intramuscular needle, silver wire and surface electrodes as well as the use of raw and averaged as root mean square (rms) values (0.1 sec time constant) fully rectified electrical signals have been compared in the study of the function of erector trunci muscles during normal forward bending and extension. All the techniques indicate that during standing and flexion, the muscles are electrically silent. The use of surface electrodes and the averaging technique provides similar, although slightly damped, recordings as those obtained with the aid of intramuscular silver wire electrodes. The function spectra during the simple forward flexion .sbd. reextension cycles appear to be highly reproducible. During the cycle the electrical activity in the eccentric phase is lower than in the concentric one. In back pain, there is an increased electrical activity during static phases, modified activities are seen during the kinetic phases. The surface measurings with the average technique of signal handling to document the back muscle function, permit an application of EMG in outpatient care and physical therapy conditions.