If you’ve spent any time in a commercial gym, you’ve seen it. Someone grabs a pair of dumbbells that are way too heavy, starts swinging their torso like a pendulum, and calls it a set of hammer curls. It’s painful to watch. They’re getting plenty of momentum, sure, but their biceps are basically on vacation.
Hammer curls are arguably the most underrated arm builder in your arsenal. Unlike the standard palms-up (supinated) curl, the hammer grip targets the brachialis and the brachioradialis. These are the muscles that sit underneath your biceps and along your forearm. When they grow, they literally push your biceps up higher, making your arms look thicker from the side. But if you aren't doing them right, you're just wasting energy.
The best way to do hammer curls isn't just about moving weight from point A to point B. It’s about tension. It’s about making a 25-pound dumbbell feel like 50 because your form is so locked in.
Stop Swinging and Start Growing
The biggest mistake is the ego. We all want to lift the big weights. But the moment your elbow drifts forward or your shoulder shrugs up to your ear, the tension leaves the muscle.
To get the most out of this movement, you need to pin your elbows. Imagine there is a bolt running through your ribs and into your elbow joints. They shouldn't move. When you curl the weight, the only thing moving should be your forearm.
I’ve found that a slight lean forward—just a few degrees—can actually help take the tension off the front deltoids. If you stand perfectly upright or, heaven forbid, lean back, your shoulders take over. That's not what we want. We want those thick, cable-like forearms that make sleeves tight.
The Secret is the Brachialis
Most people think of the biceps as one big muscle. It’s actually more complex. The brachialis is a deep muscle. It doesn't get much love in a traditional curl because the supinated grip favors the biceps brachii. By turning your palms inward to a neutral grip, you put the biceps brachii at a mechanical disadvantage. This forces the brachialis to do the heavy lifting.
Think of the brachialis as the "wedge" of the arm. If you develop it, your bicep peak will naturally look more impressive. It’s like putting a lift kit on a truck; the foundation raises everything else.
Then there’s the brachioradialis. That’s the meaty part of your upper forearm. If you’ve ever wondered why some guys have massive forearms but skinny wrists, it’s usually because they’ve mastered the best way to do hammer curls. They’re hitting that neutral grip consistently.
Variations That Actually Work
You don’t have to just stand there and curl both arms at once. In fact, you probably shouldn't.
- Alternating Hammer Curls: This is the gold standard. By focusing on one arm at a time, you can really connect with the muscle. It also prevents that weird rocking motion that happens when you try to heave two dumbbells up simultaneously.
- Cross-Body Hammer Curls: Instead of bringing the weight toward your shoulder, you bring it toward your opposite pec. This slightly changes the angle of pull and can often feel more "natural" for people with certain wrist or elbow issues. It hits the outer head of the bicep a bit harder too.
- Seated Incline Hammers: Sit on an incline bench set to about 60 degrees. Let your arms hang straight down. Because your arms are now behind your torso, the long head of the bicep is stretched to the max. This is brutal. Honestly, the pump you get from these is borderline disrespectful.
Handling the Weight: Grip and Tempo
Don't just squeeze the dumbbell; crush it. A tighter grip creates something called irradiation. Basically, when you grip something hard, the surrounding muscles—your forearms, biceps, and even your shoulders—fire more effectively.
And please, for the love of gains, slow down the eccentric. That’s the lowering phase. If you just let the weight drop, you’re missing out on 50% of the muscle-building potential of the set. Take two full seconds to lower the weight. Feel the stretch. It’s supposed to burn. If it doesn't, you're probably just gravity's assistant.
Why Your Elbows Might Hurt
If you feel a sharp pain in the "crook" of your elbow, you might be overextending at the bottom or using too much weight. The best way to do hammer curls involves a controlled range of motion. You don't need to lock out your elbows so hard they click. Keep a "soft" elbow at the bottom to maintain constant tension.
Real-World Programming
Don't make hammer curls the "main event" of your workout. They are an accessory lift. You should do your heavy rows or weighted chin-ups first. Those are your compound movements. Once the big muscles are fatigued, move to the hammers.
Three sets of 10-12 reps is usually the sweet spot for hypertrophy. If you can do 15 reps with perfect form, it’s time to move up in weight. But remember: a 5-pound jump in dumbbells is a lot for a small muscle group. Don't be afraid to stay at the same weight for a few weeks while you focus on slowing down the tempo.
Actionable Steps for Your Next Arm Day
To truly master the best way to do hammer curls, you need a plan that moves beyond just "lifting things up and putting them down."
- Film yourself. Seriously. Side profile. You’ll be shocked at how much your elbows move when you think they’re still.
- Use a thumbless grip occasionally. Sometimes taking the thumb out of the equation helps you stop "muscling" it up with your hands and forces the brachioradialis to work harder.
- Try the "1.5 Rep" Method. Curl the weight all the way up, lower it halfway, curl it back to the top, then lower it all the way. That counts as one rep. It’s a fast track to forearm thickness.
- Pair them with triceps. Doing a "super-set" of hammer curls followed by overhead tricep extensions creates a massive pump because you’re filling the entire upper arm with blood.
- Focus on the squeeze. At the very top of the movement, hold it for a split second. If you can’t hold it, the weight is too heavy.
Focusing on these nuances transforms a basic movement into a specialized tool for arm thickness. Consistency here matters more than the specific weight on the bar. Fix the form, slow down the tempo, and the growth will follow.