Which muscle is primarily activated when performing hammer curls instead of standard curls?

When performing hammer curls, the brachioradialis muscle is primarily activated due to the specific grip used during the exercise. The hammer curl involves holding the dumbbells in a neutral position with the palms facing each other, which shifts some of the focus away from the biceps brachii and places greater emphasis on the brachioradialis muscle located in the forearm.

The brachioradialis is particularly engaged throughout the curling motion, which allows it to assist in flexing the elbow. The neutral grip used in hammer curls also allows for a more functional movement pattern that mimics various activities in daily life, facilitating better muscle engagement compared to a traditional curl.

Different from hammer curls, standard curls predominantly target the biceps brachii, while the triceps brachii and forearm flexors play a much smaller role in this specific movement. Thus, the unique grip and lifting style of hammer curls distinctly activate the brachioradialis more effectively than other muscles involved in elbow flexion.