Hammer Curls

Setting up the hammer curl

The hammer curl is mechanically simple. The neutral grip and straight up curl path make it one of the easiest curl variations to perform correctly. Rep quality and load discipline are what produce results.

1. Stance and grip

Stand with feet hip width apart. Hold the dumbbells at the sides with palms facing the body in a neutral grip. The thumbs point forward. Arms hang straight down from the shoulders. The dumbbells should rest against the outside of the thighs at the start position.

2. The brace

Take a breath and brace the abdominals. The trunk stays rigid throughout the rep. Shoulders pulled slightly down and back. The chest is up. The elbows are pinned at the sides. The neutral wrist position remains constant throughout the rep.

3. The curl

Curl both dumbbells up by flexing the elbows. The wrists stay in the neutral position throughout. The dumbbells travel in a straight vertical line up to shoulder height. The thumbs stay pointed up. The elbows stay pinned at the sides throughout the curl.

4. The peak contraction

Hold the top position for one second. The dumbbells sit at shoulder height. The elbows are fully flexed. The wrists are neutral. This pause is what allows the brachialis to fully shorten under load and what separates a real hammer curl from a momentum driven swing.

5. The descent

Lower the dumbbells under control over two seconds. The wrists stay neutral throughout. The arms fully straighten at the bottom. Resist the temptation to drop the dumbbells. The controlled eccentric is where brachialis and brachioradialis hypertrophy stimulus is greatest.

What hammer curls train

The hammer curl trains the elbow flexors with emphasis on the brachialis and brachioradialis rather than the biceps brachii. The neutral grip is what produces this muscle distribution.

Brachialis

Primary mover. The brachialis sits beneath the biceps and is loaded heavily by neutral grip curls. EMG studies show hammer curls produce some of the highest brachialis activation of any curl variation. For lifters chasing thick upper arms hammer curls are one of the most direct exercises.

Brachioradialis

Primary mover. The most prominent forearm muscle that contributes significantly to elbow flexion. The neutral grip biases the brachioradialis more than supinated curls. Visible forearm thickness is largely built by neutral grip curls including hammer curls.

Biceps brachii (short head)

Loaded but less than in supinated curls. The neutral grip reduces biceps brachii peak activation because the biceps cannot fully shorten in supination. The short head of the biceps still contributes meaningfully which is one reason hammer curls produce some bicep development as a secondary effect.

Forearm flexors and grip

The forearm flexors hold the dumbbells. Grip is rarely a limiting factor at standard hammer curl weights. The neutral grip is the most natural grip position for the wrist which makes high rep hammer curl work tolerable without wrist discomfort.

Five errors on hammer curls

The hammer curl is forgiving but several common errors steal the brachialis bias or load the lower back. The most common failures relate to trunk position and grip orientation.

Wrist rotation during the curl

Some lifters rotate the wrist from neutral to slightly supinated during the curl. This turns the lift into a standard dumbbell curl, not a hammer curl. The neutral wrist position is what biases the brachialis. The thumbs should stay pointed up throughout every rep.

Swinging with the trunk

Using a trunk swing to throw the dumbbells up moves the load to momentum. The trunk should stay rigid throughout the set. If trunk movement is needed to complete reps the weight is too heavy. Drop ten percent and rebuild.

Elbows drifting forward

If the elbows move in front of the body during the curl the anterior delt takes the load. The elbows should stay pinned at the sides. The hammer curl makes this slightly easier than supinated curls because the neutral grip is more stable.

Curling outward

Some lifters allow the dumbbells to drift outward away from the body during the curl. The dumbbells should travel straight up. The forearms should sit roughly parallel to each other at the top. Outward drift reduces brachialis loading.

Going too heavy

Hammer curls are mechanically slightly stronger than supinated curls because the brachialis and brachioradialis assist more. Productive working weights are typically 10 to 15 percent heavier than supinated dumbbell curls. NSCA Essentials supports honest loading over ego loading.

Sets, reps and where hammer curls fit

Hammer curls are accessory work. They sit alongside supinated curls in any complete arm programme. The neutral grip and the brachialis focus make them complementary rather than redundant with supinated curl work.

Hypertrophy: 8 to 12 reps

The productive range. 3 to 4 sets of 8 to 12 reps at moderate loads. Stop 1 to 2 reps short of failure. The brachialis and brachioradialis bias makes this exercise particularly responsive to volume in this range.

High volume: 12 to 20 reps

Higher rep hammer curls work as a finisher. 2 to 3 sets at lighter loads at the end of an arms session. The neutral grip is comfortable for high rep work and the brachialis responds well to longer time under tension.

Strength: 5 to 8 reps

Heavier hammer curls build elbow flexor strength. 3 to 4 sets of 5 to 8 reps at heavier dumbbells. Maintain strict elbow and wrist position throughout. The hammer curl allows slightly heavier loading than supinated dumbbell curls.

Frequency

2 to 3 sessions per week is well tolerated. Hammer curls recover quickly because the loads are moderate and the joint stress is low. Many balanced programmes include them in every arms session as a brachialis focused finisher.

Pairing

Pair hammer curls with supinated dumbbell or barbell curls for complete elbow flexor development. The hammer version builds brachialis and brachioradialis. The supinated version builds biceps brachii. The combination produces complete upper arm development across all major elbow flexors.

More on bicep training

For the brachialis biased cross body version, our Cross body hammer curls guide covers the diagonal curl angle. Zottman curls are the hybrid neutral and supinated curl. And the Rope Cable Curl page covers the neutral grip cable alternative.