Abstract
In occupational field studies surface electromyography can be applied to determine muscular strain and to indicate the occurrence of muscular fatigue. Muscle strain is commonly indicated by using the amplitude of the electromyogram (EMG) or measures thereof, muscle strain is indicated by determining the time course of the EMG with respect to changes in the EMG amplitude or power spectral distribution. For both purposes a detailed knowledge on the current activity of the person under test is needed for the total time under investigation. This can be attained by using a special coding system in which an electrical action code is recorded together with the EMG signals.
For the indication of muscular fatigue it has to be considered that the EMG amplitude as well as the EMG spectrum depend not only upon the fatigue state but also upon the produced muscle force. Therefore EMGs should only be compared for situations connected with similar muscle load. This demand can be fulfilled (i) by the execution of test contractions of known force in a defined posture, (ii) by comparing the EMG during situations connected with a similar activity or (iii) in a recently developed approach by the joint analysis of EMG amplitude and spectrum (JASA).
Get full access to this article
View all access options for this article.