Hammer Curl

The hammer curl swaps the palms-up grip of a standard curl for a neutral, palms-facing-in hold, shifting some work from the biceps brachii onto the brachialis and brachioradialis. That makes it one of the best exercises for building overall arm thickness and a bigger forearm, not just biceps peak. It's a joint-friendly accessory movement — the neutral grip is often more comfortable than full supination — and needs nothing more than a pair of dumbbells. This guide covers strict form, the muscles it trains, how to program it, and the mistakes that turn it into a shoulder-swinging mess.

What muscles does the hammer curl work?

The hammer curl trains the same elbow flexors as a standard curl, but the neutral, thumbs-up grip changes the balance of work between them. Keeping the forearm neutral throughout the rep — rather than rotating to a fully supinated, palms-up position — shifts more emphasis onto the brachialis, the muscle beneath the biceps that pushes it up and adds arm thickness, and the brachioradialis, the prominent forearm muscle that runs to the thumb side of the wrist. The biceps brachii still contributes to elbow flexion, but plays a smaller relative role than in a supinated curl.

How grip and angle change muscle activation

EMG research comparing curl handgrips found the supinated grip actually produced the highest brachioradialis and biceps activation of the three positions tested — a result that runs against the common assumption that a neutral grip always maximizes the brachioradialis.

• Supinated vs. neutral vs. pronated grip: Biceps and brachioradialis excitation was greater with a supinated grip than with neutral or pronated grips, with no meaningful difference between neutral and pronated.
• Practical takeaway: The neutral hammer grip still trains the brachialis and brachioradialis effectively and is easier on the wrists for many lifters, even if it isn't the highest-EMG option in every study.

Based on EMG research. [1]

How do you do the hammer curl?

To do the Hammer Curl: stand tall holding a dumbbell in each hand with a neutral grip, palms facing your torso, arms fully extended; brace your core, keep your chest up, and pin your elbows to your sides; curl both dumbbells up by flexing your elbows, keeping your wrists neutral the entire rep; squeeze at the top of the rep without letting your elbows drift forward or your shoulders shrug.

1. Stand tall holding a dumbbell in each hand with a neutral grip, palms facing your torso, arms fully extended.
2. Brace your core, keep your chest up, and pin your elbows to your sides.
3. Curl both dumbbells up by flexing your elbows, keeping your wrists neutral the entire rep.
4. Squeeze at the top of the rep without letting your elbows drift forward or your shoulders shrug.
5. Lower the dumbbells back to full elbow extension under control — don't let them drop.
6. Reset your posture briefly at the bottom before starting the next rep.

What are the key hammer curl form cues?

Elbow position

Keep your elbows pinned to your sides for the whole set — letting them drift forward turns the movement into a front raise for your shoulders.

Neutral wrist

Keep your palms facing each other the entire rep. Rotating toward supination turns the exercise into a standard curl.

No body English

Keep your torso vertical and still. Rocking your hips or leaning back to launch the dumbbells is momentum, not arm strength.

Breathing & tempo: Exhale as you curl the dumbbells up and inhale as you lower them. A 1-1-2 tempo (1s up, 1s pause at the top, 2s lowering) keeps tension on the arm flexors and prevents momentum from taking over.

How should you warm up for the hammer curl?

Do 1-2 light sets of 12-15 reps with a light pair of dumbbells to prime the elbow flexors and wrists, then add one ramping set at roughly 60% of your working weight before your first work set.

What are the most common hammer curl mistakes?

• Swinging the torso and hips, or shrugging the shoulders, to launch the weight — Brace your core and keep your torso still. If you need to rock or shrug, drop the load and rebuild strict reps.
• Letting the elbows drift forward away from your sides — Keep elbows pinned at your sides — drifting forward shifts load onto the front delts and shortens the range.
• Rotating the wrist toward supination during the rep — Keep your palms facing each other throughout — rotating turns the exercise into a standard curl.
• Dropping the dumbbells on the way down instead of controlling the eccentric — Lower each dumbbell for a full 2-3 second count — the eccentric drives a lot of the growth stimulus.

Why does the hammer curl hurt — and how do you fix it?

Pain during a hammer curl usually points to a setup or momentum problem, not the curl itself. Match your symptom to the fix below — see a professional if pain is sharp or persistent.

How many sets and reps should you do?

Choose your sets and reps by goal: heavier and fewer reps for strength, moderate for muscle size, lighter and higher for endurance.

RPE / RIR: Most working sets should land around RPE 7-8 (2-3 reps in reserve) with strict form. Save RPE 9-10 sets for the last set of a session, once your technique is dialed in.

The hammer curl is an accessory movement, so program it after your main compound lifts — squats, presses, rows, deadlifts. Two to three sessions a week, spaced with at least a day of recovery for the elbow flexors, is enough for most lifters. Progress by adding a rep or two each week before moving up to the next dumbbell.

How often should you hammer curl and where does it fit?

Train the Hammer Curl 2-3 sessions per week, placing it after your main compound pulling and pressing work, as one of the last 1-2 exercises.

• Frequency: 2-3 sessions per week
• Best split days: Pull day (Push/Pull/Legs), Arm day (bodybuilding split), Upper day (Upper/Lower)
• Where to place it: After your main compound pulling and pressing work, as one of the last 1-2 exercises

Pair it with a triceps exercise as a superset, or rotate it with a standard dumbbell curl across the week for balanced arm development.

How do you progress the hammer curl?

To curl heavier dumbbells, train the movement 2-3x/week with strict form, add a rep or two before adding load, and give the elbow tendons real recovery time between sessions.

What's the right range of motion?

Train from a full, straight-arm bottom position to a full contraction at the top, pausing briefly at the top of each rep. Lengthened partials — small reps in the bottom, stretched portion of the range — are a useful add-on once your full-range strength is established, but they should supplement full-range sets, not replace them.

What are the benefits of the hammer curl?

• Builds forearm and brachialis thickness alongside the biceps for a fuller-looking arm
• Uses a neutral grip that's often more comfortable than full supination for sensitive wrists or elbows
• Trains each arm independently, exposing and fixing left-right strength imbalances
• Simple to program as an accessory, with no rack or bar setup needed

Who should do it: Bodybuilders chasing overall arm thickness rather than just biceps peak, lifters whose wrists or elbows are irritated by full supination, and anyone building grip and forearm strength for other lifts.

Is the hammer curl safe?

The hammer curl is a low-risk exercise for most healthy lifters because it's a single-joint movement performed standing with a light-to-moderate load, and the neutral grip is generally gentler on the wrists than a supinated curl.

Wrist or forearm discomfort with other curl variations

The neutral grip is usually the most comfortable curl option — start light and build up gradually.

Elbow tendon pain (golfer's/tennis-elbow type)

Reduce volume and load, loosen your grip, and slow the tempo down until symptoms settle.

Spotting: A spotter isn't necessary — it's a single-joint, standing movement you can safely fail by simply setting the dumbbells down.

How do grip and stance change the hammer curl?

• Neutral (standard hammer) grip: Palms face each other throughout — the default choice, easier on the wrists than a supinated curl.
• Cross-body hammer curl: Curling toward the opposite shoulder increases the range of motion and adds a rotational component.
• Rope or cable hammer curl: Keeps constant tension through the range and lets you adjust the angle relative to your torso.

Hammer Curl variations

How does the hammer curl compare?

Hammer Curl vs. Dumbbell Curl

The standard dumbbell curl uses a supinated grip and biases the biceps brachii most directly. The hammer curl uses a neutral grip throughout, shifting more emphasis onto the brachialis and brachioradialis for arm and forearm thickness.

Hammer Curl vs. Reverse Curl

The hammer curl uses a neutral, palms-in grip and is comfortable for most wrists. The reverse curl uses a fully pronated, palms-down grip, which trains the brachioradialis and forearm extensors even more directly but is harder on the wrists.

Hammer Curl alternatives

Estimate your hammer curl 1RM

Enter a weight and the reps you hit with it to estimate your one-rep max (Epley formula), then see your training percentages.

How many calories does the hammer curl burn?

Calories depend on your bodyweight and how hard you train. Resistance training has a MET value of about 3.5. Enter your bodyweight and minutes to estimate the burn (calories = MET × kg × 3.5 ÷ 200 × minutes).

Hammer Curl strength standards

Approximate one-dumbbell (single-arm) hammer curl one-rep max as a multiple of bodyweight, based on aggregated lifter data. Treat these as motivating benchmarks rather than hard targets.

By age: Curl strength tracks training age more than age in years through your 40s. Lifters in their 40s can aim for about 90% of these numbers, 50s about 80%, and 60s+ about 65-70%.

What counts as a good rep?

A hammer curl rep counts when you lower the dumbbells to a full, straight-arm position and curl them back up to a full contraction at the shoulder without rotating your wrists toward supination or swinging your torso to help move the weight.

References

1. Coratella G, Tornatore G, Longo S, Toninelli N, Padovan R, Esposito F, Cè E. Biceps Brachii and Brachioradialis Excitation in Biceps Curl Exercise: Different Handgrips, Different Synergy. Sports (MDPI/PMC), 2023
2. How to Do Hammer Curl: Muscles Worked & Proper Form. StrengthLog
3. Hammer Curls: Benefits, Muscles Worked, and Variations. Healthline
4. How To Do Hammer Curls. ATHLEAN-X
5. Dumbbell Hammer Curl — classification, muscles and instructions. ExRx.net
6. Hammer Curl Strength Standards for Men and Women. Strength Level (aggregated lifter data)
7. Golfer's Elbow (Medial Epicondylitis): Symptoms & Treatment. Cleveland Clinic