Musculocutaneous nerve injury after heavy exercise.

Three cases of musculocutaneous nerve injury distal to its innervation of the coracobrachialis muscle are reported. The syndrome typically features painless weakness of the biceps brachii and brachialis muscles, sensory loss in the distal volar forearm, a history of recent vigorous upper extremity resistive exercise, and resolution of the problem on resting the affected extremity. In all three reported cases the dominant arm was involved. The condition should not be confused with C-5 or C-6 radiculopathy, brachial plexopathy, or rupture of the biceps brachii muscle belly or tendon.