Hammer Curl: Muscles Worked and How to Do It
TL;DR
Hammer curls work your biceps as the prime mover, bending your elbow to lift the dumbbell. The neutral, palms-facing-in grip also recruits the brachialis, a deeper elbow flexor that sits under the biceps, giving your upper arm a fuller, more complete contraction than a standard curl.
- Primary muscle:
- Biceps
Muscles worked
Your biceps brachii is the main mover in a hammer curl, contracting to bend your elbow and lift the weight. Because your palms face each other instead of facing up, the exercise also recruits the brachialis, a muscle that sits underneath the biceps and adds thickness to the upper arm.
Keeping your palms neutral throughout the lift keeps tension focused on these elbow flexors rather than shifting it to your wrist rotators, which is what happens in a standard curl. That makes the hammer curl a straightforward, joint-friendly way to build arm size.
Log Hammer Curl in PR Streak
PR Streak's library has 873 exercises, each with photos and step-by-step instructions like this one. Log this move and see what you lifted last time right next to every set, with every PR caught automatically and a chart for every exercise.
How to do it
- Stand up with your torso upright and a dumbbell on each hand being held at arms length. The elbows should be close to the torso.
- The palms of the hands should be facing your torso. This will be your starting position.
- Now, while holding your upper arm stationary, exhale and curl the weight forward while contracting the biceps. Continue to raise the weight until the biceps are fully contracted and the dumbbell is at shoulder level. Hold the contracted position for a brief moment as you squeeze the biceps. Tip: Focus on keeping the elbow stationary and only moving your forearm.
- After the brief pause, inhale and slowly begin the lower the dumbbells back down to the starting position.
- Repeat for the recommended amount of repetitions.
Form tips
- Keep your palms facing each other the entire rep: don't rotate your wrists.
- Keep your elbows pinned to your sides instead of letting them drift forward.
- Lower the dumbbells under control instead of letting them drop.
- Avoid swinging your torso to heave the weight up; if you need momentum, the load is too heavy.
- Squeeze at the top of the rep before lowering back down.
Exercise details
| Equipment | Dumbbell |
|---|---|
| Level | Beginner |
| Mechanic | Isolation |
Used by lifters following PPL, 5x5, upper/lower, and more.
Frequently Asked Questions
What's the difference between a hammer curl and a regular curl?
A regular curl uses a palms-up grip that emphasizes the biceps' role in rotating your forearm. A hammer curl uses a neutral, palms-in grip, which shifts some of the work to the brachialis, a deeper elbow flexor, for a thicker-feeling arm without changing the exercise's basic elbow-bending pattern.
How many reps of hammer curls build muscle?
For muscle size, work in the 6-12 rep range at roughly 67-85% of your one-rep max, controlling the lowering phase. A 1RM calculator can help you estimate that number if you train curls for strength as well as size.
More biceps exercises
Exercise instructions and photos come from the free-exercise-db library, public domain, the same library used inside the PR Streak app.
