Influence of heat on fatigue and electromyographic activity of the biceps brachii muscle

Electromyography enables registering muscle activity during contraction and can identify muscle fatigue. In the present study, 30 volunteers between 18 and 30 years of age were submitted to an exertion 1 min of maximal voluntary isometric contraction. The electromyographic signal of the biceps brachii muscle and the strength of the flexor muscles of the elbow were determined before and after the administration of microwave diathermy in order to analyze the influence of heat over the strength of the elbow flexor muscles and fatigue of the biceps brachii. The results demonstrate that the strength of the elbow flexor muscles diminished significantly following the application of heat (p < 0.05). Heat also led to a significant reduction in the electrical activity of the muscle studied. The present study demonstrates that microwave diathermy on the biceps brachii muscle reduces the flexion strength of the elbow as well as signs of muscle fatigue in the biceps.