What muscles do hammer curls work?

The biceps and the forearms. Compared with a regular curl, the neutral grip puts more of the work on the brachialis (under the biceps) and the brachioradialis (on top of the forearm).

Are hammer curls better than regular curls?

Neither is better; they shift the work slightly. Regular curls train the biceps most, hammer curls bring in more of the brachialis and forearms. Doing both covers the elbow flexors well.

Why can I lift more on hammer curls?

With a neutral grip, the brachialis and brachioradialis can contribute more, so most people curl a little more weight than with their palms up.

Do hammer curls make your arms bigger?

They can: the brachialis lies under the biceps, and when it grows it pushes the biceps up and adds thickness to the upper arm. Like any muscle, it grows with enough hard sets over time.

Hammer Curl: Muscles Worked and How to Do It

Hammer curl: muscles worked and how to do it

The hammer curl trains your biceps and your forearms. Holding the dumbbells with your thumbs up (a neutral grip) shifts more of the work to the brachialis, the muscle under your biceps, and to the brachioradialis, the big muscle on top of your forearm, than a curl with your palms up.

You curl the dumbbells up with your palms facing each other, as if you were swinging two hammers, keeping your elbows by your sides. Many people find the grip easier on the wrists than a regular curl, and they can usually handle a little more weight.

At a glance

Main muscles: Biceps
Forearms
Movement: Bend the elbow (curl)
Equipment: Dumbbells, Cable machine
Type: Isolation (one joint)

Front

Back

How to do a hammer curl

Stand tall with a dumbbell in each hand, arms by your sides, palms facing your thighs.
Keep your elbows close to your sides and your shoulders still.
Curl the dumbbells up, keeping your thumbs pointing up the whole way, until your forearms are close to vertical.
Squeeze briefly at the top without letting your elbows drift forward.
Lower the dumbbells slowly until your arms are fully straight again.

Cues that help

"Thumbs to the ceiling": the grip stays neutral from bottom to top; no turning the palms.
"Elbows glued to your sides": they bend, they do not travel.
"Squeeze the handle": a firm grip brings in the forearms.
"All the way down": a full stretch at the bottom of every rep.

Common mistakes

Swinging the weight up with your hips and back. If you need momentum, the dumbbells are too heavy.
Elbows drifting forward at the top, which hands part of the lift to the front of your shoulders.
Stopping short at the bottom. Half reps skip the stretched part of the movement.
Rushing the lowering. Two seconds down is a good habit.

Hammer curl or regular curl?

Both train the biceps. With your palms up, as in a regular dumbbell curl, the biceps does the most work; with your thumbs up, the brachialis and the forearm muscles take a bigger share. That is why many programmes use both: they train the same joint from two angles.

If regular curls bother your wrists or elbows, the hammer grip is often more comfortable, and it is a good choice when you want stronger forearms and grip.

Sets, reps and weight

For muscle: 3 to 4 sets of 8 to 15 reps.
Rest about 1 to 2 minutes between sets.
Pick a weight you can curl without swinging, with a controlled lowering on every rep.
Progress with reps first, then move up a dumbbell size once you reach the top of your range on every set.

Variations and alternatives

Cross-body hammer curl: curl each dumbbell across your body towards the opposite shoulder.
Cable hammer curl: a rope on a low pulley keeps tension on the arm from the start.
Alternating hammer curl: one arm at a time, which makes swinging easier to spot.
Dumbbell curl: palms up, more biceps.
Preacher curl: the arm rests on a pad, so cheating is almost impossible.

Tracking your hammer curls

PushBeyond logs the weight and reps of each set and charts the history of the exercise, so you can see your curls go up over the weeks. Its muscle map counts the hammer curl for your biceps and forearms.