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.

Analysis of electromyographic activity of ankle muscles on stable and unstable surfaces with eyes open and closed.

INTRODUCTION: Proprioceptive exercises are performed on a daily basis in physiotherapy with the use of different unstable platforms in order to improve joint stability using the mechanical and sensory properties of ligaments, joint capsule and integrated activity of the muscles surrounding the joint. Changes in the myoelectrical characteristics of the muscles during activity can be identified using surface electromyography (EMG), which provides important information on the behavior of muscles submitted to different types of load. OBJECTIVES: The aim of the present study was to analyze the electromyographic activity of the tibialis anterior, tibialis posterior, peroneus longus, gastrocnemius lateralis and gastrocnemius medialis on stable and unstable surfaces with eyes open and closed. METHODOLOGY: Twenty-five active, healthy, male and female individuals were submitted to an anthropometric evaluation and a protocol involving warm up and the electromyographic assessment of muscle activity on different surfaces. The order of the data collection was chosen randomly by lots [on stable ground or unstable platforms (trampoline, balance platform, proprioceptive disk and proprioceptive board) with eyes open and on a trampoline, balance platform and stable ground with eyes closed]. The individuals remained balanced on these surfaces for 15 s with the knee at 30° flexion in order to provide greater instability. RESULTS: There was a significant increase (p < 0.05) in muscle activity on the unstable surfaces, with the exception of the trampoline, which did not achieve statistically significant differences in relation to the stable ground. The tibialis anterior and peroneus longus exhibited the greatest electromyographic activity on all surfaces. The proprioceptive tests performed with eyes closed exhibited significantly greater electromyographic activity than with eyes open. CONCLUSION: Proprioceptive exercises on unstable surfaces generated a significant increase in electromyographic activity, especially with eyes closed, and are therefore a valuable resource in the sensory-motor rehabilitation of the ankle.