The Hammer Curl | Bang Your Biceps | Bust Your Forearms

The hammer curl is an exercise that involves the forearm muscles being isolated and targeted, with a thumbs-up grip helping to emphasize a particular part of the biceps.


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Strength athletes across a variety of sports share a common appreciation for larger arms. Examples such as Shi Zhiyong, a Chinese weightlifter, Taylor Atwood, an elite powerlifter, and Tia-Clair Toomey-Orr, a CrossFitter, demonstrate impressive upper arm development and is an asset shared by these athletes. Though their goals may vary, stronger and bigger arms can provide a benefit in any strength sport.

Strong biceps can help reduce the risk of injury during heavy deadlifts and are a key muscle group in performing pull-ups. To maximize bicep development, the hammer curl offers a unique alternative to the traditional dumbbell curl that can help to increase grip strength and promote heavier weight lifting. Here is an overview of how to perform the hammer curl and its potential benefits. Although this exercise may not lead to elite-level performance, it can be an effective way to develop bicep strength.

How to Do the Hammer Curl

This guide provides step-by-step instructions on how to execute a two-arm dumbbell hammer curl properly. This variation of the hammer curl lines up the working arm with the resistance, helping to increase tension in the arms while reducing the risk of injury to the elbow and shoulder.

1. Grip the Dumbbells

While standing upright, hold a dumbbell in each hand and ensure that your wrists are securely positioned. Gently squeeze your shoulder blades together to ensure that your shoulders are properly locked into place, and focus the effort on engaging your biceps muscles.

Fat Gripz can assist in enhancing grip strength by expanding the diameter of the dumbbell, thus increasing the muscular activity of the forearm muscles. As a result of the diminished strength when using Fat Gripz, it is advised to carry out additional exercises to target bicep strength specifically.

2. Curl the Weights

Maintaining rigidity in the wrist, engage the shoulder muscles and grip the handles securely. All that is needed is an elbow flexion and extension.

Maintain a narrow range of motion for the elbow joint when performing bicep curls. Excessive motion can result in tension loss in the bicep muscles. Ensure that the dumbbell forms a near-half circular arc from the hip to the front of the shoulder.

Once you have reached the point of full elbow flexion, with the thumb at shoulder level, hold the dumbbell at the apex of the hammer curl and contract the biceps. To maximize muscle tension, ensure you complete the rep with deliberate and controlled speed.

Resist the temptation to use momentum to lift the dumbbells. If you have to swing to lift the load, the weights you have chosen are too heavy. This will prevent proper activation of the biceps, reduce the weight and perform the exercise with a controlled motion.

3. Squeeze and Then Lower The Load

While maintaining elbow positioning beneath or slightly ahead of the shoulder, return dumbbells to the initial starting position at a deliberate and regulated speed.

When descending the weights, visualize the same arced trajectory when elevating the dumbbells to the apex.

Hammer Curl Mistakes to Avoid

The hammer curl is an uncomplicated exercise; nevertheless, this requires strict adherence to proper form, eliminating any possibility of faulty execution. The following are some of the most commonly seen technique errors.

Rotating Your Hands

Any variation of the hammer curl with the hands in a position other than thumbs-up is considered a different exercise. This is not incorrect, rather, it targets different muscles due to the altered positioning of the hands and wrists.

Imagine doing a flat bench press; rather than gripping the bar with your hands slightly outside shoulder-width as with a regular flat bench press, your hands are almost touching with a close-grip bench press. Although the overall exercise is still valid, the close-grip technique works more on the triceps than the chest.

Therefore, it is essential to ensure that during hammer curls, the hands are held perpendicular to the ground and the palms facing inwards. A slight alteration in grip can create a changed outcome.

Ensure you are performing Hammer Curls, not Pronated (palms facing down) Curls, Supinated (palms facing up) Curls, or an Angled Grip in-between. Visualize yourself “hammering a nail” to ensure an accurate exercise form. To perform Hammer Curls correctly, avoid an angled swing and keep your thumbs facing up.

Swinging Your Body

When performing hammer curls, it is important to avoid swinging the torso to lift the weights from the bottom, as this increases strain on the lower back and reduces biceps activation. Oftentimes, this unconscious movement is caused by selecting a set of dumbbells that are too heavy; however, many lifters are guilty of this regardless of the weight.

To prevent upper body swinging, lifters should begin each rep from an upright posture with arms at the side, abs tense, and shoulders pulled back. Further, bracing and contracting the abs while curling and lifting at a slower speed can make upper body swinging more preventable.

Remember to be methodical and pay attention to using good form in a controlled, smooth movement. There’s no need to exceed your capacity. Doing the Hammer Curl with good form and lighter weight will win the day; in the long run, controlling the speed of the curl can aid in preventing you from swinging.

Benefits of the Hammer Curl

The hammer curl engages the upper and lower arm muscles, providing a more comprehensive outcome than other curl variations.

The hammer curl offers a range of benefits by enabling greater muscle activation and the ability to lift heavier weights, making it a bonus exercise for any arm-busting routine.

Bigger Biceps

Due to their role in elbow flexion (curling and bending), the biceps are the primary muscles recruited when performing hammer curls. This makes them an important muscle group for achieving increased muscular size in the upper arms.

Bigger Forearms

Despite very few people doing direct forearm work, hammer curls are an uncomplicated and successful approach to strengthening the muscles below and above the elbow. The neutral (thumbs up) grip increases the intensity on various muscles of the forearm compared to the supinated (palms up) technique.

Increased Grip Strength

A firm grasp has been linked to better overall health, not to mention its transferable benefits to other activities. Hammer curls are an effective means of increasing grip strength without integrating specialized exercises into one’s exercise routine.

Muscles Worked by Hammer Curl

The hammer curl is more than just a bicep exercise. Its unique hand position activates a range of muscles in the upper and lower arm, making it an important exercise for any comprehensive arm workout. By incorporating this move into your routine, you can make sure that all of the muscles in your arm are being adequately worked. This will help you to develop the definition and strength you desire, while also reducing the risk of injury.

Biceps Brachii

The biceps brachii is a two-headed muscle located in the front of the upper arm. It is the most superficial muscle of the arm, located between the shoulder and elbow joint. It is composed of two distinct heads: the long head, which originates from the supraglenoid tubercle of the scapula, and the short head, which originates from the coracoid process. The long head passes superiorly and laterally in the arm, while the short head passes superiorly and medially. Both heads converge near the middle of the arm, joining at the bicipital aponeurosis and later inserting onto the radius bone at the radius tuberosity.

The primary action of the biceps is elbow flexion, and both heads of the biceps are strongly activated when performing this movement. The long head is also activated when raising the arm at the shoulder, known as shoulder flexion. Furthermore, both heads of the biceps are strongly activated when performing pronation and supination movements of the wrist, which involves the rotation of the forearm in order to move the palm from a pronated position to a supinated position or vice versa.


The brachialis muscle, located near the elbow beneath the biceps brachii, is often referred to as a “hidden” muscle because it is not visible from the outside. This muscle is responsible for the flexion of the forearms, and its enlargement can have a significant role in the overall size of the arm. When the brachialis muscle size increases, it can “push” the biceps higher, resulting in a larger arm size overall. This is why many professional bodybuilders and athletes focus on isolating the brachialis muscle through specific exercises, like hammer curls and reverse curls. When it comes to arm size, the brachialis muscle is worth training.

The brachialis is the primary muscle responsible for the flexion and extension of the elbow joint. It does not contribute to supination or pronation of the forearm, meaning that it is only involved in flexion and extension of the joint. For this reason, a neutral-grip (palms facing each other) is generally recommended when training the brachialis, as it places the muscle in a strong mechanical position. This is why you can typically use more weight with any neutral-grip curling, rowing, or pulling exercises than a pronated or supinated grip, which lacks the same mechanical advantage.


The brachioradialis is a muscle located along the thumb side of the forearm, running from the distal end of the humerus to the base of the second metacarpal bone. This muscle is particularly prominent near the elbow and contributes significantly to the overall muscle size of the forearm. It is responsible for stabilizing the forearm during arm movement, acting as a synergist to the bicep brachii and brachialis muscles.

The wrist flexors and extensors are important muscles in the forearm and are involved in gripping activities. The wrist flexors, located on the palm-side of the forearm, are responsible for flexing the wrist joint and consist of the flexor carpi radialis, flexor carpi ulnaris, palmaris longus, and flexor digitorum superficialis.


The wrist flexors, primarily composed of the flexor carpi radialis, flexor carpi ulnaris, palmaris longus, and flexor digitorum superficialis, are responsible for the flexion and abduction of the hand. These muscles are found on the palmar side of the forearm and are heavily involved in any grip-intensive exercise, such as the hammer curl. During this exercise, the wrist flexors work actively to hold the weight in place, while the wrist extensors, which include the extensor carpi radialis, extensor carpi ulnaris, anconeus, and extensor digitorum, provide stability.

Who Should Do the Hammer Curl

The hammer curl is an effective exercise for increasing muscle size and strength. It serves as an excellent complementary exercise for those who are focused on maximizing their upper arm size, as well as those looking to increase their overall power and strength.

Lifters Training for More Muscle

The hammer curl is an ideal exercise for anyone looking to add size to their arms, including their forearms. Too often, forearms get left out of an arm workout, but hammer curls can help round out your bicep training to ensure that your entire arm gets the attention it needs. Some lifters may be hesitant to add another arm exercise due to time constraints or the desire to be as efficient as possible with their workouts. But the hammer curl is a perfect choice for making the most of a single exercise. Not only does it provide an effective bicep workout, but it also targets the forearms effectively.

Lifters Training for Strength

The benefits of having strong arms and a strong grip reach far beyond just looking good at the beach. It can have a positive impact on nearly any exercise that requires you to hold onto a bar or weight, like deadlifts, pull-ups, barbell or dumbbell rows, etc. A secure grip on the bar can help improve bar control, stability, and even your overall power output. It’s why grip strength is such an important factor in strength training and if you’re looking to improve your grip strength.

How to Program the Hammer Curl

The hammer curl is a great exercise for strengthening the upper arms, but it shouldn’t be thought of as just a light weight and high rep exercise. Incorporating it into your fitness routine correctly can provide even more effective results. Here are a few tips to help you make the most out of hammer curls:

Heavy Weight, Low to Moderate Reps

The hammer curl is an effective exercise for building strength and size in the biceps due to its neutral-grip positioning. By having the hands in a neutral position, the arms are put in a stronger pulling position than if the hands were turned palm-up. This allows for greater strength gains and heavier weights to be used with proper technique.

Start with an appropriate weight. Don’t be afraid to use heavier weights than you would for other arm curls – remember, the heavier the weight, the more muscle fibers you’re stimulating. Change up the tempo. Hammer curls are typically done with a slow, controlled movement, but switching up the tempo can add an extra challenge to the exercise.

Performing four to five heavy sets of six to eight repetitions of the hammer curl can significantly increase strength.

Hammer curls performed using traditional bodybuilding methodology, with 3 to 4 sets of 8 to 12 reps, is a proven method to increase arm muscle mass. Such an exercise regimen should provide an intense feeling of muscle growth in the forearms and biceps.


Do hammer curls increase grip strength?

Hammer curls can be beneficial in targeting the muscles that control grip strength and elbow flexion.

Can beginners perform hammer curls?

Certainly, novices can do the hammer curl and its related exercises. This exercise is relatively straightforward, so it should not take beginners long to master it and start developing the size and strength of their arms.

Are dumbbells better than using cables for hammer curls?

Comparing dumbbells and cables, it is clear that neither is superior to the other. To optimize one’s training, a variety of methods should be employed, including free weights, cables, and machines. Dumbbells rely on gravity for resistance, whereas cables provide the most even tension, directly in line with the cable. By considering the purpose of the training, one can determine which tool is most suitable for the job.