[The reaction of EMG-activity during intermittent isometric muscle work (author's transl)].

The reaction of EMG-activity depending on workload level and break duration is analyzed under the condition of tiring dynamic muscle work on a hand-dynamometer. With the experimental set-up different workload levels (i.e., threshold of developed muscular force in relation to the individual maximum force level) and constant contraction frequencies as well as constant break durations could be given as external working conditions. The experiments were accomplished with 12 subjects. By means of a standardization of the EMG-activity the data were compared and evaluated interindividually. Thus, statistically significant results were obtained. Whereas muscular fatigue under static workload conditions results in a remarkable increase of EMG-activity, this could not be found under intermittent load conditions, even in the state of muscular exhaustion, if the break duration was longer than 2 s. The results are discussed with regard to the possibly different mechanisms of muscular fatigue under these working conditions.