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Hammer Curl

Also called: Neutral-grip curl

Primary muscles: Brachialis

Secondary muscles: Biceps brachii, Brachioradialis

Joints / actions: Elbow joint (humeroulnar joint) (flexion)

Plane: sagittal

Equipment: dumbbells

What it is

Holding dumbbells with palms facing each other (neutral grip), curling them up toward the shoulders and lowering with control.

Purpose

Emphasizes the brachialis, which works consistently regardless of forearm rotation, by removing the supination component of a standard curl.

Starting position

Stand holding dumbbells at your sides with palms facing your body (neutral grip), elbows close to the torso.

Step by step

Keeping the wrists neutral (palms facing in) throughout, curl the dumbbells up by bending the elbows.
Squeeze briefly at the top.
Lower under control back to full arm extension.

Breathing

Exhale as you curl up; inhale as you lower.

Coaching cues

"Palms facing in the whole time, elbows still, controlled tempo."

Common mistakes

Rotating the wrists toward a palm-up position during the lift (turning it into a standard curl); swinging the torso; rushing the lowering phase.

Easier regression

Use a lighter load, or perform one arm at a time for more control.

Harder progression

Increase load, or add a pause at the top of the range.

Alternatives

Barbell bicep curl (more biceps emphasis), cable hammer curl.

Who may benefit

Anyone wanting complete elbow-flexor development alongside standard curls.

Who should modify or avoid it

Those with wrist discomfort in a neutral grip should check dumbbell size/shape or reduce load.

Why this exercise works

The neutral grip removes the supination action that the biceps specializes in, shifting relatively more of the elbow-flexion demand onto the brachialis, which works the same regardless of forearm rotation.

⚠ Safety note

Same general precautions as other curls — keep the elbows stable and avoid using momentum.

Sources

“The brachialis flexes the elbow regardless of forearm rotation, unlike the biceps brachii which is most active when supinated.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.5 Muscles of the Pectoral Girdle and Upper Limbs

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19

“The brachioradialis flexes the elbow most effectively in a neutral forearm position, as used in a hammer curl.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.5 Muscles of the Pectoral Girdle and Upper Limbs

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19