ProgreviaHammer curl: proper form, muscles worked and common mistakes
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How to do it
Neutral grip (palms facing) to load the brachialis and brachioradialis as well as the biceps. Curl without swinging, keeping the elbows pinned to the torso, and control the lowering.
Muscles worked
Main muscle: biceps. When it plans weekly volume, every set of this exercise counts in full for biceps: the generator does not split it with other muscles.
Hammer curl vs. Zottman curl: what the neutral grip changes
The hammer curl keeps your palms facing each other from start to finish. The Zottman curl lifts with the palms up, then rotates the wrists at the top and lowers with the palms down. That makes the hammer curl the simpler lift: there's no rotation to coordinate, your wrist stays put, and you can usually pick heavier dumbbells because the load isn't capped by a slow, palms-down lowering. Compared with a barbell curl or an alternating dumbbell curl, the neutral grip shifts more of the work to the brachialis and the forearm, so the biceps stops being the only star of the show.
Pick it when you want a stable, no-fuss curl, when a fully supinated grip bothers your wrist, or when arm and forearm thickness is the goal. It fits after a main curl such as the EZ bar curl or the preacher curl, or first in the session if the brachialis is your priority. Working in the 8 to 12 rep range and moving up in dumbbell weight only once every set is done with still elbows is a practical way to progress.
One detail unique to this version: hold the handle like a hammer with your thumb wrapped around it, and don't over-squeeze. If your forearm gives out before your arm does, your grip is too tight.
Technical sheet
- Movement pattern
- Isolation
- Minimum level
- Beginner
- Technical demand
- Basic
- Fatigue it generates
- Low (0.5 out of 2.2)
- Risk if technique breaks down
- Low
These are the values the generator uses to decide where the exercise goes within the session.
Recommended sets and reps
As an isolation exercise, it works best in 3–4 sets of 10–15 reps with 0–2 RIR. Use it at the end of the session to add volume without systemic fatigue.
Common mistakes to avoid
- Swinging the body and letting the elbows drift forward, turning the curl into a shoulder movement.
- Letting your dominant side do more of the work: each arm or leg completes the same range, at the same pace.
- Using too much weight at the cost of technique and full range of motion.
What the research says
This is an isolation exercise. For beginners, adding it on top of compound lifts does not always help: in the trial by Gentil and colleagues (2013), people who only did lat pulldowns gained as much arm size as those who also did curls. It earns its place with experience, and for muscles the big lifts leave short.
On how hard to push: the meta-analysis by Refalo and colleagues (2023) found no clear advantage in going to failure over stopping just short of it. That is why the generator programs it with reps in reserve (RIR) instead of asking for failure on every set.
- Gentil P, Soares SR, Pereira MC, et al. Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects. Applied Physiology, Nutrition, and Metabolism. 2013;38(3):341-344.
- Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine. 2023;53(3):649-665.
How Hammer curl compares with other biceps exercises
Of the 16 biceps exercises in the catalogue, ranked from least to most fatiguing by the values the generator uses, Hammer curl is number 4 (tied with 9 others).
That makes it a good candidate for adding biceps sets at the end of a session or in heavy weeks, when you want volume without extra fatigue.
With different equipment, the same movement pattern offers 10 alternatives, such as Band concentration curl, Resistance band biceps curl and Band hammer curl.
| Exercise | Equipment | Fatigue | Technique |
|---|---|---|---|
| Overhead cable curl | cable | Low (0.5 out of 2.2) | Basic |
| Low cable curl | cable | Low (0.5 out of 2.2) | Basic |
| Incline dumbbell curl | dumbbells | Low (0.5 out of 2.2) | Basic |
| Reverse barbell curl | barbell | Low (0.5 out of 2.2) | Basic |
| Hammer curl | dumbbells | Low (0.5 out of 2.2) | Basic |
| Zottman curl | dumbbells | Low (0.6 out of 2.2) | Needs coaching |
| Barbell curl | barbell | Low (0.6 out of 2.2) | Basic |
| EZ bar curl | barbell | Low (0.6 out of 2.2) | Basic |
An isolation exercise. In the trial by Gentil et al. (2015), with untrained young men over ten weeks, the biceps curl and the lat pulldown were equally effective for gaining strength and size in the elbow flexors: isolation is not filler.
- Gentil P, Soares S, Bottaro M. Single vs. multi-joint resistance exercises: effects on muscle strength and hypertrophy. Asian Journal of Sports Medicine. 2015;6(2):e24057.
Related guide
Best biceps and triceps exercises for bigger arms
Alternative exercises
More isolation exercises
Add it to your routine
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Frequently asked questions
What muscles does Hammer curl work?
Hammer curl mainly works the biceps muscle group, plus synergist and stabilizer muscles depending on the variation.
How many sets of Hammer curl should I do?
Between 3 and 5 sets per session, adjusting the total weekly volume for biceps to your level (about 10–20 sets per muscle per week).
Does the hammer curl work the biceps or just the forearms?
Both. The biceps still flexes the elbow, but with your palms facing each other the brachialis and brachioradialis take on a bigger share of the effort. That's why you tend to feel it on the outer arm and in the forearm. It doesn't replace a supinated curl, so pair it with one to make sure every elbow flexor gets work.
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