Yes, hammer curls train the biceps while also loading the brachialis and brachioradialis, which can add arm size, grip strength, and elbow-flexion power.
Hammer curls sit in that sweet spot between simple and misunderstood. Some lifters file them under forearm work. Others treat them like the same move as a standard curl with the hands turned in. The truth sits in the middle: hammer curls are for biceps, but they are not only for biceps.
That split matters when you’re building an arm workout. If you treat hammer curls like a copy of the classic underhand curl, you’ll miss what makes them worth doing. If you write them off as forearm work, you’ll undersell how much they can add to a fuller upper arm.
Are Hammer Curls For Biceps? What The Grip Changes
Yes, the biceps still work hard in a hammer curl because your elbow is bending against load. But the neutral grip changes the job. Your palms face each other, so the biceps lose part of the extra edge they get during strong supination. That leaves more room for the brachialis and brachioradialis to pull their share.
That’s why hammer curls feel different from a strict underhand curl even when the weight is close. The front of the upper arm still lights up. You just feel more of the upper forearm and more of that dense “packed” tension through the whole elbow-flexor group.
The brachialis sits under the biceps. Build it well, and the upper arm can look thicker from the side and front. The brachioradialis runs along the upper forearm, so hammer curls also give the lower arm more shape than many curl variations.
Why Lifters Notice Hammer Curls Fast
Hammer curls usually feel stable. Your wrists stay in a neutral line, the dumbbells track close to the body, and the setup is easy to repeat from set to set. For many lifters, that means less fiddling and more clean reps.
They also fit almost anywhere. You can do them after rows, after chin-ups, on a full arm day, or at the end of a short upper-body session when you still want direct arm work without a lot of setup.
What Hammer Curls Do Better Than Standard Curls
Standard curls and hammer curls overlap, but they do not build the same look in the same way. The underhand curl leans harder into the biceps’ role as an elbow flexor and palm-up driver. The hammer curl spreads the load across the whole elbow-flexor group a bit more.
- More total arm balance: You’re not chasing the biceps peak alone. You’re training the muscles under and beside it too.
- A steadier wrist position: Many people find the neutral grip easier to repeat with clean form.
- Strong carryover to pulls: The grip and elbow path line up well with rows, carries, and chin-up work.
- Easy load jumps: Dumbbells make it simple to add weight in small steps.
That does not mean hammer curls beat every other curl. It means they fill a lane that straight curls do not fill as well. If fuller arms are the goal, that lane is worth keeping.
Hammer Curls For Biceps Growth And Arm Width
If your plan only includes underhand curls, you can still grow good arms. But adding hammer curls gives you another growth driver. According to Cleveland Clinic’s elbow anatomy page, elbow flexion is shared by the biceps, brachialis, and brachioradialis, while the biceps also helps turn the palm up.
A peer-reviewed handgrip study found that changing forearm position changes how the biceps brachii and brachioradialis share the work during curl variations. That lines up with what lifters feel in the gym. Standard curls often hit the front of the upper arm with a sharper squeeze. Hammer curls spread tension in a way that can make the whole arm look denser.
One is not a replacement for the other. Together, they make more sense than either one alone. If you want the biceps to look bigger from the front, side, and three-quarter angle, hammer curls earn their spot. They won’t give the same peak bias as a supinating curl, but they can add the thickness that makes the arm look built even when it isn’t flexed.
| Point | Hammer Curl | Standard Curl |
|---|---|---|
| Hand Position | Neutral grip, palms facing each other | Supinated grip, palms facing up |
| Main Feel | Upper arm plus upper forearm | Front of upper arm |
| Biceps Involvement | High | High, with more supination bias |
| Brachialis Involvement | Usually stronger | Still trained, but less emphasized |
| Brachioradialis Involvement | Usually stronger | Lower for many lifters |
| Wrist Comfort | Often easier to keep neutral | Can feel stiff for some wrists |
| Best Use | Arm thickness, forearm tie-in, balanced elbow flexion | Biceps squeeze, peak-focused curling |
| Smart Pairing | Works well after rows or after standard curls | Works well before hammer curls |
That comparison also explains why hammer curls tend to stay in routines for a long time. They are easy to recover from, easy to load, and easy to pair with other arm work. You don’t need to build a whole workout around them to get a clear payoff.
Form Details That Make Hammer Curls Work
Hammer curls are easy to butcher. The usual problem is not the grip. It’s the ego. Once the weight gets too heavy, the lift turns into a half-rep swing with the shoulders and lower back doing more than the elbows.
ACE’s hammer curl form cues are simple and sharp: keep the wrist straight, keep the elbow from drifting forward, and lower the weight with control. Those three points clean up most bad reps.
How To Set Up Each Rep
- Stand tall with a dumbbell in each hand and your palms facing in.
- Let the weights hang by your sides without rolling the shoulders forward.
- Brace your midsection and keep your ribs stacked over your hips.
- Curl by bending at the elbow, not by rocking the torso.
- Stop just before the shoulder takes over, then lower under control.
A Simple Cue That Fixes Most Sets
Think “zip the dumbbells up, then place them down.” That cue keeps the rep smooth. It also stops the drop phase from turning into a free fall, which is where tension usually disappears.
Mistakes That Steal Growth
- Swinging the torso: If the hips snap, the weight is too heavy.
- Letting the elbows drift forward: That pulls the front delts into the rep too soon.
- Bending the wrist: The forearm takes a sloppy path and the curl gets messy.
- Rushing the way down: The lowering phase is part of the set, not dead time.
One more thing helps a lot: stop one rep before your form breaks. Hammer curls respond well to honest reps. Five clean reps near failure beat eight loose reps with body swing every time.
Where Hammer Curls Fit In A Biceps Plan
The cleanest way to use hammer curls is to pair them with one curl that lets the palm turn up hard. That pairing gives you the squeeze of a supinated curl and the denser arm work of the neutral-grip version. You don’t need a long arm day to make that work.
A good starting point is 2 to 4 working sets after your bigger pulling lifts. Keep most sets in the 8 to 15 rep range, train close to failure with clean form, and add load only when the last reps stay crisp. If progress stalls, add reps first, then weight.
| Goal | How To Use Hammer Curls | Starting Volume |
|---|---|---|
| General Arm Size | Place them after rows or pulldowns | 3 sets of 8–12 |
| Biceps Plus Forearm Tie-In | Pair with underhand curls in the same workout | 2–3 sets of 10–15 |
| Grip And Carryover To Pulls | Use a slower lowering phase | 3 sets of 6–10 |
| Elbow-Friendly Arm Work | Use dumbbells and a smooth tempo | 2–4 sets of 10–12 |
| Short Upper-Body Sessions | Finish with alternating hammer curls | 2 sets of 12–15 |
When To Put Them First
If your upper arms lag in thickness, run hammer curls earlier once or twice a week. That small shift can lift effort and rep quality. If your biceps peak is the main target, put an underhand curl first and hammer curls second.
Who Gets The Most From Hammer Curls
Hammer curls make sense for most lifters, but they shine for a few groups. New lifters usually pick up the form fast. People with stiff wrists often like the neutral grip more than a straight underhand curl. Lifters chasing fuller arms also tend to keep them in year-round because the carryover is easy to see.
They’re also handy when straight-bar curls irritate the wrists or elbows. A neutral dumbbell path gives each arm a little freedom, and that can make training feel smoother. If pain is sharp or sticks around outside the gym, don’t grind through it. Step back, trim load, and sort the issue before piling on more volume.
When Another Curl Variation May Fit Better
Hammer curls are not the whole answer. If you want more peak, an incline dumbbell curl or a strict preacher curl may earn more room. If you want the hardest forearm bias, reverse curls may fit better. If you want steady tension from start to finish, cable curls can be a strong match.
That’s why the smartest call is not “hammer curls or biceps curls.” Hammer curls are a biceps exercise. They just train the arm through a different grip and a different feel. Use them as part of the curl lineup, not as the only ticket.
The Real Answer
Hammer curls are for biceps, and they’re also for the muscles that make the arm look complete. That mix is what gives them value. Do them with a clean neutral grip, control the lowering phase, and pair them with at least one supinated curl if fuller arm growth is the target.
If your workouts already have rows, chin-ups, and standard curls, hammer curls can be the missing piece that rounds out the upper arm and upper forearm. They’re not flashy. They just work when the reps stay honest.
References & Sources
- Cleveland Clinic.“Elbow Joint: Anatomy, Function & Common Conditions”Explains elbow flexion, supination, and the roles of the biceps, brachialis, and brachioradialis.
- European PMC.“Biceps Brachii and Brachioradialis Excitation in Biceps Curl Exercise: Different Handgrips, Different Synergy”Shows how different curl grips shift muscle excitation during biceps curl variations.
- American Council on Exercise.“Hammer Curl”Gives form cues on neutral wrist position, elbow path, and controlled lowering during hammer curls.