Hammer Curl
Primary
Biceps
Secondary
Brachialis, Brachioradialis, Forearms
Equipment
Dumbbell
Difficulty
Beginner
Type
Pull
Hammer Curl
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Hammer curls shift the emphasis from your biceps brachii to the brachialis muscle that lies beneath it. The neutral grip (palms facing each other) also heavily recruits the brachioradialis of your forearm. This makes hammer curls essential for building arm thickness rather than just bicep peak.
Maintain the neutral grip throughout—do not let your palms rotate upward during the curl. Think about driving your thumbs toward your shoulders rather than curling your pinkies up. This cue keeps the brachialis and forearms engaged.
Muscles worked: Hammer Curl
Why This Exercise Works
Hammer curls shift the primary workload from the biceps brachii to the brachialis and brachioradialis—two muscles that contribute significantly to arm thickness but are underworked by standard supinated curls.
The brachialis sits underneath the biceps brachii and is a pure elbow flexor—it does not participate in forearm supination. Because the hammer curl uses a neutral grip (palms facing each other), the biceps brachii loses its mechanical advantage for supination, and the brachialis picks up a larger share of the elbow flexion force. EMG research shows that neutral-grip curls produce 10-15% higher brachialis activation compared to supinated curls. Exercise science identifies the brachialis as the key muscle for arm thickness when viewed from the front because it pushes the biceps peak upward as it grows.
The brachioradialis is the large forearm muscle running from your outer upper arm to your wrist. It is the most powerful elbow flexor when the forearm is in a neutral or pronated position. During hammer curls, the brachioradialis handles a significant portion of the load—more than in any supinated curl variation. This makes hammer curls one of the most effective exercises for forearm development without needing dedicated wrist work.
The biceps brachii still activates during hammer curls—it cannot fully disengage from elbow flexion. However, its contribution is reduced by roughly 20% compared to supinated curls because the neutral grip eliminates the supination component. Research notes that this makes hammer curls complementary to standard curls rather than a replacement.
The wrist extensors on the back of your forearm work isometrically to maintain the neutral wrist position against the weight of the dumbbell. This stabilization demand is one reason hammer curls build overall forearm strength and size more effectively than supinated curls.
Grip strength benefits from hammer curls because the neutral grip aligns with your forearm bones (radius and ulna) in their strongest position. This allows heavier loading compared to supinated curls—most lifters can hammer curl 10-20% more weight than they can dumbbell curl with supination. Using this heavier loading capacity to drive progressive overload on arm training is recommended, as strength researcher Greg Nuckols has documented.
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Hammer Curl form guide
- 1
Stand holding dumbbells with neutral grip (palms facing each other).
- 2
Keep elbows pinned to your sides.
- 3
Curl weights up while maintaining neutral wrist position.
- 4
Squeeze at the top of the movement.
- 5
Lower under control to starting position.
- 6
Repeat without swinging.
What are the best tips for the Hammer Curl?
Keep palms facing each other throughout the entire movement.
This grip targets the brachialis for arm thickness.
Can be done alternating or simultaneously.
When to Use the Hammer Curl
Program hammer curls alongside supinated curls for complete arm development. They work well as a secondary movement after barbell or dumbbell curls, or as a primary movement on forearm-focused days. Include them 1-2 times per week for balanced arm thickness.
What are common Hammer Curl mistakes to avoid?
Rotating wrists during the curl - changes muscle emphasis.
Swinging weights with body momentum - reduces effectiveness.
Not fully extending at the bottom - limits range of motion.
Is the Hammer Curl right for you?
All levels. Great for building arm thickness and forearm strength.
How many sets and reps of Hammer Curl should you do?
Recommendation: 3 sets of 10-12 reps. Rest 60 seconds.
Muscle Growth
8-12 reps
Rest 90s-2min
Strength
4-6 reps
Rest 2-3min
Endurance
15-20 reps
Rest 60s
Where to Use in Your Workout
Program hammer curls as a secondary bicep movement after supinated curls, or as a primary movement when forearm development is the priority. Include 1-2 times per week. 6-12 direct bicep/brachialis sets per week across all curl variations. Rep range: 8-12 for strength-hypertrophy, 12-15 for metabolite work. Rest 60-90 seconds. Most lifters can use 5-10 lbs heavier than dumbbell curls due to the stronger neutral grip position.
Sample Workout Blocks
Arm Day (Thickness Focus): 1. Barbell Curl — 3x8-10 (90s rest) 2. Hammer Curl — 3x10-12 (60s rest) 3. Reverse Curl — 2x12-15 (60s rest) Total arm volume: 8 sets targeting brachialis + brachioradialis
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Get Your Custom PlanWhat are good alternatives to the Hammer Curl?
Cross Body Hammer Curl
Cable Hammer Curl
Dumbbell Curl
Other Variations
- Cross Body Hammer Curl
- Rope Hammer Curl
- Incline Hammer Curl
Variation Details
Cross-Body Hammer Curl
Curl the dumbbell across your body toward the opposite shoulder instead of straight up. This adds shoulder adduction, which emphasizes the long head of the biceps while still targeting the brachialis. Use the same weight as standard hammer curls.
Rope Hammer Curl
Perform hammer curls using a rope attachment on a low cable. The cable provides constant tension throughout the range of motion, unlike dumbbells which lose tension at the top. Excellent for metabolite accumulation in the 12-15 rep range.
Incline Hammer Curl
Sit on an incline bench (45-60 degrees) and perform hammer curls with arms hanging behind your torso. This stretches the brachialis at the bottom of the movement, increasing range of motion and stimulus. Use 15-20% less weight than standing hammer curls.
Hammer Curl vs Other Exercises
Dumbbell curls with supination target the biceps brachii more directly for peak development. Hammer curls target the brachialis and brachioradialis for arm thickness and forearm size. Include both for complete arm development—supinated curls for the peak, hammer curls for width.
vs Reverse Curl
Reverse curls use a pronated (palms-down) grip, which maximally loads the brachioradialis and wrist extensors but uses the least weight of any curl variation. Hammer curls allow heavier loading while still significantly targeting the brachioradialis. Use hammer curls as your primary forearm builder and reverse curls as a finishing exercise.
Frequently Asked Questions About the Hammer Curl
Neither is better—they target different muscles. Regular supinated curls emphasize the biceps brachii (peak). Hammer curls emphasize the brachialis and brachioradialis (thickness). For complete arm development, include both in your program.
Alternating lets you handle slightly more weight per arm and focus on each rep. Both arms simultaneously is faster and provides more core stabilization demand. Cross-body hammer curls (curling toward the opposite shoulder) add a long head emphasis. Pick based on your goal and available time.
The neutral grip places your forearm bones in their mechanically strongest position and allows the brachioradialis—a powerful elbow flexor—to contribute maximally. This combined force output exceeds what the biceps brachii can produce alone with a supinated grip.
Yes. Hammer curls are one of the most effective forearm builders because the brachioradialis handles a large portion of the load. The wrist extensors also work isometrically to maintain grip. Many lifters find that consistent hammer curl training eliminates the need for dedicated forearm isolation.
Standard hammer curls move straight up and down. Cross-body hammer curls angle the dumbbell across your body toward the opposite shoulder. The cross-body path increases long head biceps involvement due to the shoulder adduction component. Both are effective—use standard for brachialis focus, cross-body for long head emphasis.
Yes, the Hammer Curl can be done at home with a dumbbell. It requires minimal space and is a great option for home workouts targeting biceps.
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Safety Notes
- Keep elbows stationary.
- Use controlled movements throughout.