Forearm Positioning on Maximal Elbow-flexor Force

Integrated electromyograms and cable-tensiometer scores were recorded simultaneously from the major elbow flexors of thirty male subjects during the performance of maximal isometric elbow-flexor contractions with the forearm either pronated, supinated, or midpositioned. The results showed that both the biceps brachii and the brachioradialis muscles were most active electrically when the forearm was supinated or in midposition; both muscles were least active electrically with the forearm pronated. The pronator teres muscle area was equally active electrically in all three forearm positions. The isometric elbow-flexor force exerted with the elbow flexed at 65 degrees was greatest when the forearm was supinated or midpositioned, and was lowest with the forearm pronated.