Electromyography: some methodological problems and issues.

The purpose of this review is to discuss electromyography (EMG) and some of the problems and issues that are encountered during the recording and interpretation of EMG data. Recordings of electrical activity of muscles can be contaminated by interference from the electrical supply, mechanical artifacts, stimulus artifacts, and activity of other muscles. The advantages and disadvantages of surface electromyography and intramuscular EMG are compared and contrasted, and precautions to be taken when recording and interpreting these data are described. Surface electromyography is usually more susceptible to artifacts than is intramuscular EMG. It is possible, however, to make useful recordings with the surface electrodes from large superficial muscles if appropriate precautions are observed. Intramuscular electrodes, on the other hand, may be preferred for recording the activity from small peripheral muscles or muscles located deep within the body.