The biceps brachii consists of two muscular heads: the short and the long head. Functionally, the biceps can do two things: flex the elbow and supinate the forearm. Supination is simply the act of turning the palms face up. When the forearm is in a neutral position (wrists straight), the greater muscles of the forearm, namely the brachioradialis, are heavily involved in elbow flexion.

Listed below are instructions for performing the hammer curl:

From a standing position, hold two dumbbells by your sides. Your wrists should be in a neutral position. Raise both dumbbells up to shoulder height, then lower them back down to the starting position.