Hammer Curl

What is the Hammer Curl?

The hammer curl is a biceps curl done with a neutral, palms-facing-in grip, like swinging a hammer. That grip shifts emphasis onto the brachialis (which sits under the biceps) and the forearm, making it a go-to for building arm thickness and grip alongside the biceps peak.

Muscles worked

Primary: Biceps

The biceps brachii still flexes the elbow, but the neutral grip also loads the brachialis beneath it, which pushes the biceps up and adds width to the upper arm.

Secondary: Forearms

The forearm muscles, the brachioradialis especially, work hard in the neutral grip to raise and control the dumbbell.

How to perform the Hammer Curl

1. Stand holding dumbbells with a neutral grip so the palms face each other and the thumbs point forward throughout the set.
2. Keep the wrist locked in that neutral position for the entire rep, which shifts load onto the brachialis and brachioradialis rather than the biceps peak.
3. Curl the dumbbells straight up toward the shoulders without any supination or wrist rotation.
4. Stop when the forearms are just past vertical, keeping the elbows pinned to the sides rather than drifting forward.
5. Lower the dumbbells under control back to the neutral hang, resisting the eccentric.
6. Because the brachialis sits under the biceps, expect to handle slightly more load here than on a supinated curl.

Suggested working range: 10–15 reps. Default progression: double progression.

Mechanics

A single-joint isolation: elbow flexion with the forearm held in a fixed neutral (thumbs-up) position throughout, upper arms pinned to the sides. Keeping the wrist neutral rather than supinated is what shifts load onto the brachialis and forearm.

Form cues

• •Hold the dumbbells with thumbs up and keep that neutral grip for the whole rep, no rotating.
• •Pin the elbows at your sides and curl by bending only at the elbow.
• •Squeeze at the top without letting the elbows drift forward to cheat the weight up.
• •Control the lowering phase to a full stretch instead of letting the dumbbells drop.

Common mistakes

• •Rotating the wrist toward supination mid-rep, which turns it into a regular curl and loses the brachialis bias.
• •Swinging the dumbbells up with body English instead of a strict elbow flexion.
• •Letting the elbows flare forward off the ribs to help lift heavier weight.
• •Dropping the dumbbells fast on the way down and skipping the eccentric.

Variations & alternatives

• •Cross-body hammer curl: curling toward the opposite shoulder to bias the brachialis further.
• •Cable hammer curl with a rope: keeps constant tension across the whole range.
• •Dumbbell curl, rotating to palms-up to bias the biceps peak instead.
• •Reverse curl, a pronated (palms-down) grip that hits the forearm extensors even harder.

Barbell Curl

Biceps · Barbell

Dumbbell Curl

Biceps · Dumbbell

Cable Curl

Biceps · Cable

Incline Dumbbell Curl

Biceps · Dumbbell

Concentration Curl

Biceps · Dumbbell

Programming: sets, reps & when to use it

Program the hammer curl in the library’s 10–15 rep range as a biceps and forearm accessory, typically after your back work or paired with a supinating curl for complete arm development. Keep the grip neutral and the reps strict; it builds the brachialis and forearm that a palms-up curl trains less.

Frequently asked questions