There are tons of variations of biceps curls, from basic dumbbell biceps curls to biceps curls with resistance bands or a cable machine, kettlebell biceps curls, concentration curls, and more.
Hammer curls are one of the most popular forms of the biceps curl exercise, offering some unique benefits versus standard biceps curls with dumbbells.
So, what muscles do hammer curls work? Are the “hammer curls muscles worked” different from the muscles worked by regular biceps curls or other types of biceps curls such as concentration curls or reverse biceps curls?
In this guide, we will discuss the benefits of hammer curls, how to perform them, several variations to help target different muscle fibers and add variety to the exercise, and ultimately answer your question: what muscles do hammer curls work?
We will look at:
- How to Do Hammer Curls
- What Muscles Do Hammer Curls Work?
- How to Vary Hammer Curls
Let’s get started!
How to Do Hammer Curls
Hammer curls are an excellent exercise for biceps workouts because the exercise changes the grip position from standard biceps curls to target different muscle fibers in your biceps.
Instead of your palms being in an underhand grip (supinated position) facing away from your body in the starting position, your palms face towards one another throughout the duration of the movement.
This neutral wrist position often tends to be more comfortable and natural for most lifters, allowing you to lift more weight to maximize your strength gains.
Here is how to do hammer curls with dumbbells:
- Stand upright with good posture, holding a dumbbell in each hand with your arms down at your sides. Instead of supinating your forearm so that your palms face away from your body as you would with regular biceps curls, keep your arms, wrists, and hands in a neutral position so that your wrists and palms face in towards your thigh on the side of your body.
- Contract your biceps and bend your elbows to curl the dumbbells up to your shoulders, maintaining this neutral wrist position (palms facing in toward one another). Keep your wrists rigid so that they remain in line with your forearm rather than dropping down or bending from the weight.
- Pause at the top.
- Slowly lower the weights back down with control.
What Muscles Do Hammer Curls Work?
As with any biceps curl exercise, hammer curls strengthen the biceps brachii, which is the two-headed muscle on the front of your upper arm that runs from the shoulder joint down to just below the elbow.
The primary function of the biceps brachii is flexion of the elbow, which refers to bending your elbow as well as supinating the forearm.Hammer curls also target the brachialis, which is a smaller muscle on the outer portion (lateral side) of your biceps that lies underneath the biceps in the upper arm. The brachialis muscle assists the biceps in flexing the elbow.
Another muscle worked by hammer curls is the brachioradialis, which is the primary muscle in your forearms.
The brachioradialis also helps assist with elbow flexion and supination.
While we all want to have big, popping biceps, lack of grip strength, which is primarily a matter of the strength in your forearm muscles, is actually the limiting factor for big lifts like maxing out on your deadlift or doing heavy carries or long sets of pull-ups and chin-ups.
This is definitely a significant benefit of adding hammer curls to your upper-body routine.
The main difference between the muscles used for hammer curls vs regular biceps curls is that hammer curls better target the long head of the biceps while standard curls target the short head of the biceps more.
This is because your forearm is a little more pronated rather than supinated with hammer curls.
The muscle fibers from the biceps long head fuse with the muscle fibers from the biceps short head lower down in the muscle belly of the biceps, and then the muscle tapers down to its insertion point at the elbow.
Due to the different sites of attachment on the scapula, the short head is located along the inner side of the front part of your upper arm, and the long head of the biceps is located more along the outer and upper part of the front side of your upper arm.
Hammer curls help target the biceps long head, which adds to the “peak“ of the biceps, while the biceps short head exercises help bulk out the width of the biceps.
How to Vary Hammer Curls
As with most types of biceps curls and strength training exercises in general, you can use different forms of resistance when performing hammer curls, including dumbbells, a cable machine, and resistance bands, among others.
Any form of resistance you use to perform hammer curls will target the same primary general muscles worked by hammer curls, but the emphasis on particular muscle groups or muscle fibers may vary depending on the type of resistance that you use.
Similarly, you can also do hammer curls seated or standing.
There are pros and cons to both of these hammer curl variations, but the general movement pattern is the same.
That said, standing hammer curls will require you to engage your core muscles, glutes, pelvic floor muscles, and postural muscles to maintain a strong, stable, upright trunk while you curl the weight.
The trade-off is that while standing hammer curls activate more muscle groups when performed correctly, it’s also easier to “cheat” when doing standing biceps curls by swinging the weights, using momentum, or thrusting your hips slightly to help hoist the weights.
Thus, the goal while doing standing hammer curls should be to keep your torso as stationary and rigid as possible and lift and lower the weights slowly so that you genuinely isolate the hammer curls muscles.
Here are a few variations:
#1: Cable Hammer Curls
The benefit of doing cable hammer curls versus dumbbell hammer curls is that the tension on your biceps is experienced more uniformly throughout the entire movement.
Because your muscles are under tension for a longer period of time and at different angles of the lift with cables, you can experience more significant gains in muscle strength, and you have the opportunity to target your muscle fibers with resistance at different joint angles.
When you perform cable hammer curls, it is best to use the single D handles (if you have dual cables), the double D handle (where the two D’s face one another at an angle), a hammer curl cable attachment (looks sort of like 3 sides of a rectangle, or the rope attachment.
Here is how to do hammer curls with the cable pulley machine:
- Set the pulley of the cable machine to the lowest setting and attach the hammer curl attachment so that you have a neutral grip (palms facing one another).
- Take a few steps backward so that the weight stack lifts up. This is your starting position; the weight stack should remain elevated throughout the entire set, not touching down fully after each rep.
- Keep your core tight and glutes engaged.
- Curl the handle up to your chest, keeping your shoulder blades retracted and palms facing one another throughout the entire range of motion.
- Pause at the top and then slowly straighten your elbows to lower the hammer curl attachment handle back down.
#2: Incline Hammer Curls
Incline dumbbell hammer curls increase the muscle-building stimulus for the exercise because you can extend your arms through a larger range of motion.
This increases the time under tension for the muscles worked by hammer curls (as long as you perform the exercise in a slow and controlled manner).
Additionally, because you are seated in a reclined position, it is much harder to unintentionally “cheat” and use momentum or pop your hips forward as you curl to help hoist the weight.
Here is how to do incline hammer curls with dumbbells:
- Set a weight bench to an incline of about 60° and then lay back on the bench with a dumbbell in each hand.
- Extend your arms fully so that they are hanging down by your side. Keep your shoulders pressed into the bench, but rotate your entire arm from the shoulder to keep your arms in a neutral position rather than supinated with a standard biceps curl.
- Bend your elbows to slowly curl the weights up to shoulder height and back down.
If you don’t have any equipment but want to work your biceps, check out our guide to the best no-equipment biceps workout here.