Hammer Curls vs Bicep Curls: Which Strengthens Arms Better

Michael Garrico
Published by Michael Garrico | Co-Founder & Marketing Director
Last updated: December 28, 2023
FACT CHECKED by James Cunningham, BSc, CPT
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Both hammer curls and bicep curls are great exercises to work your bicep arm muscles.

As a certified fitness trainer, together with a couple of clients, we put both the exercises to the test. It took a few weeks to see the results, which were tremendous; however, with slight differences between the two.

In this article, I will break down the differences and similarities between the hammer curls vs. bicep curls, provide my expertise on how to perform, how to program the workouts, and the one effective for building and developing the biceps and forearms.

Quick Summary

  • Hammer curls and bicep curls are both effective exercises for working the bicep arm muscles, with hammer curls primarily targeting the long head of the bicep and bicep curls working both the long and short heads.
  • The key difference between these exercises is in grip and muscle engagement; hammer curls use a neutral grip and engage forearm muscles more, while bicep curls use a supinated grip for better bicep activation.
  • According to the study from the National Center for Biotechnology Information website, supracondylar fractures of the humerus account for 15-17% of childhood extremity fractures, it's crucial to emphasize proper form and controlled movements in exercises like hammer curls and bicep curls to minimize the risk of elbow injuries, especially in younger individuals starting strength training.
  • Drawing from extensive training experience, it's clear that the choice between hammer curls and bicep curls should be based on individual goals, with hammer curls being more effective for forearm development and bicep curls for targeted bicep growth.

Hammer Curls vs. Bicep Curls: The Difference

A gym coach looking at the difference of hammer curls and bicep curls

The primary distinction between hammer curls and bicep curls is the muscles stimulated.

Bicep curls work both the long and short heads of the bicep.

The hammer curl primarily works the long head of the bicep.

This increases the effectiveness of the bicep curls in terms of growing the bicep.

A supinated grip is used for bicep curls, which is better for bicep activation.

“While the bicep curl is preferable for building bicep growth, the hammer curl engages muscle groups in the forearm and wrist more efficiently. Because the hammer curl is done with the wrist in a neutral posture, the biceps cannot produce maximum force and must rely on other muscles for assistance.”

- Daniel Dominick, Registered Physical Therapist

According to one of the studies from the PubMed website, the thumbs-up hammer curl posture avoids supination and stimulates the brachialis and brachioradialis specifically, whereas a completely supinated grip (palms up) stresses the biceps brachii [1].

The brachialis is a powerful elbow flexor that works independently of the "main" biceps brachii on the front of your upper arm.

According to another study from the National Center for Biotechnology Information website, the brachialis muscle is located under the biceps, nearer to the bone [2]. Targeting the brachialis is said to "push up" the biceps, making them look bigger.

Hammer curls also stimulate the brachioradialis, a bigger muscle that runs along the apex of the forearm and above your elbow joint, close to the bottom half of the biceps [3].

The hammer grip also stresses the small head of the biceps, whereas the palms-up grip focuses on the biceps long head [4].

The biceps curl's palms-up grip positions the biceps in a somewhat longer extended posture.

This is why you normally feel tension when your arm is fully stretched at the bottom position. The hammer curl's neutral-grip stance puts the muscles in a somewhat "rested" state rather than a longer stretched one.

Because the brachialis is solely responsible for elbow flexion and not supination, it is a comparably stronger arm muscle [5].

As a result, many lifters can execute hammer curls with greater weights than biceps curls.

What Is the Hammer Curl?

A person doing hammer curls for arm muscles

The hammer curl is a unilateral or bilateral isolation exercise that increases muscular hypertrophy and strength in most skeletal muscle groups attached along the humerus, ulna, and radius.

It is often performed with a kettlebell, or dumbbell with moderate tension and larger repetition volumes that equally train both type 1 and type 2 skeletal muscle fibers.

How to perform the hammer curl:

  1. Stand tall, holding a pair of dumbbells.
  2. Rotate each wrist such that one end of the dumbbell points forward (rather than in the direction of your body).
  3. Squeeze the biceps and curl the load onward and upward until the forearm is upright.
  4. Hold for 1-2 seconds before lowering the load gradually back to the starting position.
  5. Repeat for the desired number of reps.

Hammer Curls Benefits

As a fitness professional, I've seen hammer curls become a popular choice in workout routines due to their effectiveness in:

  • Increasing the growth and strength of the biceps
  • Enhancing wrist stability
  • Increasing muscular endurance
  • Improving grip strength

What Is the Bicep Curl?

A person doing bicep curls at the gym

The bicep curl is a bilateral or unilateral isolation exercise used to increase the strength and size of the bicep brachii. In contrast, other muscle groups relevant to biceps mechanics are relegated to stabilizer muscle duty alone.

The bicep curl, like the hammer curl, is performed with free-weight workout equipment such as kettlebells and dumbbells.

However, unlike the hammer curl, you can perform EZ bar curls or straight Olympic barbell bicep curls.

How to perform the dumbbell bicep curl:

  1. Stand tall, holding a pair of dumbbells.
  2. Pin the elbows to the sides and curl the load upward while tightening your biceps until the forearm is upright.
  3. Hold for 1-2 seconds before reducing the weight gradually back to the starting position.
  4. Repeat for the desired number of reps.

Bicep Curls Benefits

Dumbbell bicep curls have the same advantages as hammer curls because they are variations of one another.

The biceps muscle collaborates with the lats, deltoids, traps, and triceps in shoulder and elbow functions.

The most significant advantage of dumbbell bicep curls is that they are simple to learn and do.


A person holding a dumbbell

Fundamentally, both of these dumbbell curls are the same.

They demand that you move a load with strict elbow flexion, bringing the weight from the hip height to near-shoulder level.

The hammer curl and dumbbell bicep curl are isolation workouts that induce motion at a single joint (in this case, the elbow).

When you curl while swinging the weight and allowing your elbow to go away from your body, you move the shoulder joint, which may take engagement away from the biceps muscle.

“By restricting motion to a single joint, muscular tension is concentrated on the target muscle and is not distributed substantially across multiple muscles. This is why it's critical to curl with solid form and maintain your elbow close to your ribs.”

- Ben Lauder-Dykes, Certified Personal Trainer

Muscles Worked

A person doing bicep curls with good arm muscles

Both the dumbbell bicep curl and the hammer curl variations are regarded as very efficient biceps brachii isolation workouts, albeit the extent to which both movements train the biceps alone varies.

Bicep Curl Muscles Worked

The bicep curl is the very definition of a biceps isolation movement, as it primarily uses the short head of the biceps brachii muscles to move the weight most efficiently - though this can be modified slightly by changing the angle at which your forearms are in relation to the elbow.

Unlike the hammer curl, the bicep dumbbell curl does not considerably stimulate the muscle groups of the forearms or elsewhere along the upper arm, resulting in just a static use of such muscles.

This normally means that you will be unable to lift as much load as you would with a hammer curl, yet the intensity level in biceps brachii engagement should be similar.

Learn More: Best Dumbbell Biceps Exercises

Hammer Curl Muscles Worked

A person doing hammer curl workouts at the gym

Though the hammer curl is classified as a biceps isolation exercise.

The hammer curls target predominantly the long head of the bicep muscle group, enhancing upper arm thickness - all due to its neutral grip location redistributing the resistance in this manner.

Along with this activation, it has the unique ability to train the brachioradialis on the top of the forearms and the brachialis on the outer region of the upper arm close to the biceps brachii.

Development in both of these muscles will increase the arms' size and definition and grow the exerciser's pulling power, as seen in the barbell row or pull-up.

How to Program Hammer Curls and Bicep Curls

A gym coach writing down on a clipboard at a gym

In my training programs, I often use both hammer curls and bicep curls as auxiliary isolation exercises to complement compound pull-type exercises. This combination effectively trains the biceps brachii and brachioradialis, providing a well-rounded approach to arm muscle development.

Regarding rep volume, most hammer curls vs. bicep curls sets have the same number of repetitions, generally ranging between 8 - 20 reps, with more repetitions potentially indicating the necessity for higher resistance levels.

They are frequently incorporated after hypertrophy or conditioning phases that need high amounts of volume in isolation workouts in periodization employing training regimens.

Related Articles:

Which Is More Effective for Developing Biceps

The hammer curl is undeniably a good exercise for building strength and mass in the bicep muscle, but not as successful as the biceps curl itself.

This is because the biceps curl is designed exclusively for targeting the biceps brachii, with the whole mechanics directed towards employing the biceps in their full contraction range.

As a result, even with lesser resistance than the hammer curl, the biceps curl is considerably more successful in inducing appropriate training stimulus in the biceps brachii.

Which Is More Effective for Developing Forearms

A person with good forearm muscles flexing

The hammer curl is a better alternative than the biceps curl for an effective forearm builder.

Its neutral grip compels the brachioradialis to operate as a major mover muscle throughout the repetition of the hammer curl.

This can result in bigger and more powerful forearms over time and the eventual strengthening of all tissues in the wrist and elbows, increasing not only the skeletal muscle tissue but also the connective tissues and bones.

In addition to strengthening the forearms, the neutral grip posture of the hammer curl will considerably lessen the risk of a wrist injury and the amount of shear strain imposed on the connective tissues that form the wrists.

Related: Best Forearm Dumbbell Exercises: Build Strength and Mass

Which One is Safer

A gym coach holding a clipboard

Both the bicep and hammer curls are low-impact free-weight workouts that pose little to no danger of harm to the exerciser's joints and muscles.

However, in the context of the bicep curl, improper form or excessive weight can increase the risk of conditions like wrist or elbow tendonitis and shoulder impingements arising - especially if you do not perform proper preparatory work like a mobility routine and adequate warm-ups.

Another risk caused by the bicep curl but not the hammer curl is a biceps brachii tear, which occurs when you place too much strain on the biceps brachii muscle and thus tears its attachment and point of insertion at either end of the upper arm, requiring extensive rehabilitation or surgery to recuperate from.

Fortunately, this kind of injury is rare and only happens in exercisers who lift weights heavier than they can with the correct technique.

As a result, in terms of safety, the hammer curl vastly outperforms the bicep curl - albeit this is not to imply that the hammer curl is fully safe on its own.


Do Hammer Curls Make Your Arms Bigger?

Yes, hammer curls make your arms bigger. Hammer curls boost the bicep length and size. Hammer curls work the long biceps head, brachialis, and brachioradialis (both forearm muscles).

Can You Lift More Weight With Hammer Curls?

Yes, you can lift more weight with hammer curls. The hammer curl may assist you in gaining arm mass since the grip position enables you to lift greater weights.

Are Hammer Curls More Difficult Than Bicep Curls?

No, hammer curls are not more difficult than bicep curls. The hammer curl is as simple to do as the bicep curl. The hammer curl allows you to lift more weight than the bicep curl. This is because the hammer curl activates more muscles, particularly those in the forearm.

How Can Variations and Modifications of Hammer Curls and Bicep Curls Be Adapted for Different Skill Levels?

Variations and modifications of hammer curls and bicep curls can be adapted for different skill levels by adjusting the weight, grip, and range of motion to suit individual strength and experience. For beginners, lighter weights and simplified movements are recommended, while advanced lifters can incorporate heavier loads and more complex variations like incline or preacher curls.

What Are Common Mistakes and Injury Prevention Techniques for Hammer Curls and Bicep Curls?

Common mistakes in hammer curls and bicep curls include using excessive momentum and improper grip, which can lead to strain or injury; to prevent these, focus on controlled movements and proper form and avoid overloading weights. Corrective techniques involve maintaining a stable core, aligning wrists with forearms, and ensuring elbows are close to the body throughout the exercise.

How Can Hammer Curls and Bicep Curls Be Integrated into Rehabilitation Programs?

Hammer curls and bicep curls can be integrated into rehabilitation programs by using them to gently strengthen arm and shoulder muscles post-injury, with emphasis on low weights and high repetitions. These exercises can aid in recovery by promoting blood flow and rebuilding muscle strength, especially when supervised by a physical therapist.

What Is the Impact of Hammer Curls and Bicep Curls on Functional Strength and Daily Activities?

The impact of hammer curls and bicep curls on functional strength and daily activities is significant, as they enhance arm and grip strength, which is essential for lifting, carrying, and pulling motions encountered in everyday life. Regularly performing these exercises can improve overall upper body strength, making daily tasks easier and reducing the risk of muscle fatigue.

How Can Hammer Curls and Bicep Curls Be Effectively Combined in a Workout Routine?

Hammer curls and bicep curls can be effectively combined in a workout routine by alternating them on different training days or incorporating both in a single session to target various muscle groups in the arms. This combination ensures balanced muscle development and prevents overemphasis on one muscle group, leading to more symmetrical arm strength and aesthetics.


  1. https://pubmed.ncbi.nlm.nih.gov/7570586/
  2. https://www.ncbi.nlm.nih.gov/books/NBK551630/
  3. https://www.ncbi.nlm.nih.gov/books/NBK526110/
  4. https://pubmed.ncbi.nlm.nih.gov/21813298/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526813/
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About The Author

Co-Founder & Marketing Director
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James Cunningham, BSc, CPT
Staff Writer & Senior Coach
James Cunningham, BSc, CPT holds a BSc degree in Sport & Exercise Science from University of Hertfordshire. He's a Health & Performance Coach from London that brings a unique blend of academic knowledge of health supplements and practical exercise experience to the table for his readers.
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Dr. Harshi Dhingra, MBBS, MD is a published peer-reviewed author and renowned physician from India with over a decade of experience. With her MBBS from Bharati Vidyapeeth and an MD from Rajiv Gandhi University, she actively ensures the accuracy of online dietary supplement and medical information by reviewing and fact-checking health publications.
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