During a biceps curl, how do the biceps brachii and brachialis muscles interact?

During a biceps curl, the biceps brachii and the brachialis muscles work together to perform the movement, and this collaboration categorizes them as synergists. The biceps brachii is primarily responsible for flexing the elbow and supinating the forearm, while the brachialis, which lies underneath the biceps, also assists in elbow flexion but is more involved regardless of the forearm position. By acting simultaneously, these muscles enhance the efficiency of the movement and provide additional strength during the curl.

In contrast, antagonists are muscles that oppose the motion, while agonists are the primary movers in a movement. Stabilizers are muscles that help maintain posture and support the joint during movement, but in the context of the biceps curl, the interaction between the biceps brachii and brachialis is best described as synergistic.