Hammer Curl: The Ultimate Guide

The hammer curl is a valuable bicep variation that emphasizes the brachialis and forearm muscles. This guide covers proper technique, variations, and programming strategies for maximizing arm development and forearm strength.

Quick Facts

Key Benefit

Develops the brachialis and forearm muscles for thicker-looking arms and improved grip strength

Primary Muscles

Biceps, Brachialis

Secondary Muscles

Anterior Deltoids, Forearms, Traps

Equipment

Dumbbells

Difficulty

Beginner

Type

Isolation, Hypertrophy

In This Guide

Benefits

Proper Form

Muscles Used

Common Mistakes

Variations

FAQs

Related Exercises

Videos

Community Tips

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The Hammer Curl is a highly effective variation of the traditional bicep curl that offers unique benefits for overall arm development. Named for the hammer-like grip position (neutral grip with palms facing each other), this exercise shifts emphasis from the biceps brachii to the brachialis and brachioradialis muscles, leading to greater arm thickness and forearm development. While standard curls with a supinated grip (palms up) primarily target the biceps brachii, the neutral grip used in hammer curls reduces biceps involvement and increases activation of the brachialis—a muscle that lies beneath the biceps and contributes significantly to arm thickness when developed. Additionally, this grip heavily engages the brachioradialis, one of the primary forearm muscles, making hammer curls excellent for building forearm size and strength. Beyond aesthetic benefits, hammer curls strengthen the muscles and connective tissues involved in daily activities that require a neutral grip, such as carrying groceries, turning doorknobs, or using tools. They also contribute to improved grip strength, which carries over to nearly every pulling exercise in your training program. Whether you're looking to add dimension to your arm development, improve functional strength, or simply add variety to your training, the hammer curl deserves a place in your exercise arsenal. This comprehensive guide covers proper technique, common mistakes to avoid, effective variations, and programming strategies to help you maximize your results with this versatile exercise.

Why the Hammer Curl Is Worth Mastering

The hammer curl offers several distinct advantages over traditional bicep curls and should be included in a well-rounded arm training program:

Complete Arm Development

Targets the often-neglected brachialis and brachioradialis muscles, which are crucial for creating arm thickness and a three-dimensional appearance.

Wrist and Elbow Health

The neutral grip position places less stress on the wrist and elbow joints compared to supinated (palms-up) curls, making it an excellent option for those with joint discomfort.

Functional Strength Carryover

Strengthens the muscles used in neutral-grip activities encountered in daily life and sports, improving real-world performance and grip strength.

Proper Hammer Curl Form: Step-by-Step

Starting Position

Stand with feet shoulder-width apart, maintaining good posture with chest up and shoulders back.
Hold a dumbbell in each hand with arms fully extended at your sides.
Use a neutral grip (palms facing each other like holding hammers) with thumbs pointing forward.
Keep elbows close to your sides and locked in this position throughout the movement.
Engage your core slightly to maintain stability and prevent swaying.

The Movement

Keeping your upper arms stationary against your sides, exhale as you curl the weights upward by flexing at the elbow.
Maintain the neutral grip position throughout the movement (palms continue facing each other).
Curl the dumbbells up until they reach shoulder height, with forearms roughly parallel to the floor.
Focus on squeezing the brachialis and forearm muscles at the top of the movement.
Hold the contracted position briefly for 1-2 seconds.
Inhale as you slowly lower the weights back to the starting position with control, fully extending your arms without locking the elbows.
Repeat for the desired number of repetitions, maintaining strict form throughout the set.

Key Form Tips

Elbow Position

Keep elbows pinned to your sides throughout the movement to maximize arm isolation.

Grip Consistency

Maintain the neutral grip (palms facing each other) through the entire range of motion.

Controlled Movement

Avoid using momentum or "swinging" the weights up; focus on muscular contraction.

Full Range of Motion

Allow complete extension at the bottom (without locking elbows) and full flexion at the top.

Wrist Position

Keep wrists straight and neutral; don't allow them to bend up or down during the curl.

Tempo

Consider using a slower eccentric (lowering) phase of 2-3 seconds to increase time under tension.

Muscles Worked in the Hammer Curl

Primary Muscles

Brachialis: Located underneath the biceps brachii, this muscle is heavily targeted with the neutral grip and contributes significantly to arm thickness when developed.
brachioradialis: A prominent forearm muscle that runs along the thumb-side of the forearm, which is highly activated during neutral-grip curling movements.
biceps: While less emphasized than in standard curls, both heads of the biceps still contribute to the hammer curl movement, particularly the short head.

Secondary Muscles

forearms: The various muscles of the anterior forearm that flex the wrist and fingers are engaged as stabilizers during the exercise.
anterior deltoids: The front shoulder muscle provides minimal assistance during the initial phase of the curl, particularly if strict form is not maintained.
traps: Can become involved if shrugging occurs during the movement, though this should be minimized for proper isolation.

Common Mistakes and How to Avoid Them

Using momentum to swing the weights

Using body movement to help lift the weight reduces tension on the target muscles and diminishes results. Keep your upper body stable and focus on moving only at the elbow joint. If you can't curl the weight without swinging, it's too heavy. Lower the weight and focus on proper form with strict muscle isolation.

Excessive wrist movement

Allowing the wrists to bend or twist during the movement can lead to wrist strain and reduces brachialis/brachioradialis activation. Maintain a firm, neutral wrist position throughout the entire range of motion, as if your forearm and hand form a straight line extending the dumbbell.

Moving the elbows forward or outward

Allowing the elbows to come forward or flare outward turns the movement into a front raise or hybrid movement that reduces arm isolation. Keep your elbows pinned against your sides throughout the entire exercise, creating a fixed pivot point for the curling motion.

Incomplete range of motion

Not lowering the weights fully or not curling them high enough reduces the effectiveness of the exercise. Use a complete range of motion from full extension (without locking the elbows) to complete flexion, with the dumbbells reaching approximately shoulder height at the top of the movement.

Hammer Curl Variations

Body Position Variations

Seated Hammer Curl

Performing the movement while seated eliminates the potential to use lower body momentum, ensuring strict form and greater isolation of the target muscles.
Incline Hammer Curl

Executed while lying back on an inclined bench, this variation increases the stretch on the brachialis at the bottom position and creates a slightly different resistance curve.
Cross Body Hammer Curl

Curling the dumbbell toward the opposite shoulder adds a rotational component that may further enhance brachialis activation.

Execution Variations

Alternating Hammer Curl

Curling one arm at a time allows for greater focus on each side individually and may enable slightly heavier weights to be used.
Iso-Dynamic Hammer Curl

Holding one arm in the contracted position while performing reps with the other arm creates additional time under tension and a significant endurance challenge.
Eccentric-Focused Hammer Curl

Using a slow (3-5 second) lowering phase emphasizes the eccentric portion of the movement, which can stimulate greater muscle growth.

FAQs About the Hammer Curl

Both exercises effectively target the arm flexors but with different emphasis. Traditional bicep curls with a supinated (palms-up) grip primarily target the biceps brachii, particularly the long head, creating more peak height. Hammer curls with their neutral grip place greater emphasis on the brachialis and brachioradialis, contributing more to arm thickness and forearm development. The neutral grip of hammer curls also typically places less stress on the wrists and elbows. For complete arm development, both variations should be included in your training program, either within the same workout or rotated throughout your training cycle.

The ideal placement depends on your specific goals. If your primary focus is brachialis and forearm development, perform hammer curls early in your arm training when you're fresh, possibly after compound pulling movements but before fatigue sets in. If you're prioritizing overall biceps development, you might place traditional bicep curls first, followed by hammer curls as a secondary movement. Hammer curls can also be effective as a finisher to thoroughly fatigue the arms after other curl variations. Experiment with different placements to determine what works best for your specific goals and recovery capacity.

Select a weight that allows you to perform all prescribed repetitions with proper form while still challenging your muscles in the final few reps. For most people, this typically means using slightly heavier dumbbells for hammer curls than for traditional bicep curls, as the neutral grip position engages more total musculature. However, weight selection always depends on individual factors including training experience, arm strength, and specific goals. For hypertrophy (muscle growth), a weight allowing 8-12 controlled repetitions is generally effective. If you're unable to maintain strict form—particularly keeping the elbows pinned to your sides—the weight is too heavy and should be reduced.

Video Demonstrations

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Tips from the Community

Damian Banach

some bloke took my weights and wasn’t even using them the little hoarder
Oscar Palacios

Hit em wit the 30’s🤩
Jerome Phillips

Chin him
Quinton Innis

Activate your core to stabilize. Your body will naturally try to use your back to lift the weights. Activating your core/having a strong core will help against this. Using your back can strain it. Your back should not hurt after doing this. In short: don’t cheat
Brendan Izworski

dont cheat or use momentum