EMG Changes of the Forearm Extensor Muscles at Different Forearm Postures

Lateral epicondylitis is caused by repetitive and forceful movements of the forearm over long durations without sufficient rest in between. This study aimed to compare muscle length change in directions at different forearm postures. Fifteen healthy participants performed wrist extension against a force transducer at forearm pronation, supination, and neutral at 75±1% of their maximum voluntary contraction. Surface electromyography was used to record muscle activity of the extensor carpi radialis brevis, extensor digitorum communis, and extensor carpi ulnaris. There was a significant interaction between forearm posture and muscles analyzed. This study suggests that there is an opposite length change of the extensor carpi radialis brevis compared to the extensor digitorum communis and extensor carpi ulnaris, strengthening the link between pronation and supination and the development of pain at the lateral epicondyle.