Abstract
The method for evaluation of local muscle fatigue in dynamic muscular work using the surface EMG frequency shift in static test contraction was studied experimentally. Dynamic work was accomplished by elbow flexion against various loads (7, 5, 3 and 0kg) every two seconds, one run of dynamic work consisting of ten flexions. The bipolar surface EMG of the biceps brachii was recorded in test contraction using a load of 2kg before work and after each run of dynamic work until exhaustion or ten runs. The EMG was analyzed by the band pass filter technique. A practical measure of the amount of frequency shift was the increase in slow wave ratio, which was the proportion (%) of the integrated EMG in the band from 13 to 64Hz to the total EMG (13-256Hz). As run advanced the EMG showed a frequency lowering, which progressed more rapidly in heavier loading of dynamic work. The EMG frequency spectrum in test contraction recovered at six minutes after continuous twenty flexions against a load of 5kg or 7kg. It is concluded that the method can be used to evaluate local muscle fatigue in dynamic muscular work.
