How to do a hammer curl: benefits, tips and variations
When it comes to isolation exercises targeting your biceps, the hammer curl is the bicep curl's slightly edgier sister, a variation you definitely want to add to your wheelhouse for building muscle in your arms. It's also a great isolation move, which means it tackles one specific muscle group or joint, as opposed to a compound exercise that engages multiple muscle groups and joints at once. The best news is, you only need one set of dumbbells to execute the movement.
So, if you're ready to get strong arms with a new dumbbell arm exercise, then let's get going.
Meet the expert: David Wiener is a training specialist at AI-based fitness and lifestyle coaching app Freeletics
Which muscles does a hammer curl work?
Wiener explains that the hammer curl targets:
the long head of the bicep, predominantly
the brachialis (an elbow flexor in the upper arm)
the brachioradialis (one of the key forearm muscles)
How to do a hammer curl
A) Start by standing or sitting on your bench, with your back upright and your dumbbells by your sides.
B) Keep your elbows tight into your body and pull your shoulders back.
C) With your arms fully extended, curl your arms towards your chest until your thumbs are near your shoulders.
D) Hold your arms in this position for 1-2 seconds, then slowly lower your arms down.
Bicep curl vs hammer curls
Hammer curls are similar to bicep curls, but there are a few key differences:
1. Grip
Bicep curls are performed using a palms-up, or supinated, grip, while in hammer curls, the palms face each other in a neutral grip.
2. Muscles targeted
Due to the grip, hammer curls work the long, outer head of your bicep, and also target muscles in your elbow (brachialis) and outer forearm (the brachioradialis). On the other hand, bicep curls mainly target the short, inner head of the biceps muscle.
Hammer curls therefore produce more proportional strength increases, helping to reduce the risk of muscle imbalances.
3. Aesthetic results
Again, due to the slightly different muscle engagement throughout the arm, hammer curls can give your arms a thicker appearance overall than a bicep curl. Bicep curls, however, are best for giving just your upper arms that classic rounded definition.
'One of these exercises should not be chosen over the other, rather they should be used to complement each other,' says Wiener.
4 benefits of hammer curls
1. Builds arm strength and muscle
In a study done on wrestlers, a weight-training programme involving dumbbell hammer curls, tricep dumbbell extensions, preacher curls and incline dumbbell curls, among others, for the upper body, participants found a 'significant effect...on the arm strength' after eight weeks.
2. Reduces wrist strain
A study found that keeping the wrist neutral - like the neutral grip used in a hammer curl - decreased wrist muscle activity significantly, suggesting that placement of the wrist in a neutral zone was expected to reduce risk of injury.
3. Increase muscular endurance
Muscular endurance is your body's ability to keep contracting a group of muscles and exert force against resistance repeatedly. A study showed that resistance training - exercising your muscles using an opposing force, such as dumbbells - had a large positive effect on muscular endurance of the muscle worked, regardless of the load or work volume.
4. Strengthens your grip
Having a good grip, or strong muscles of your hand and forearm, is important for performing everyday functions like pouring milk into your tea or (the classic example) carrying groceries, and has been cited as a biomarker for overall health. A study showed that doing three sets of up to 10 reps of dumbbell curls for a week improved grip strength for both male and female participants.
3 common hammer curl form mistakes
It's easy to get things wrong, especially if you're training without the watchful gaze of a personal trainer or handy studio mirrors. Fortunately, there's a way to work out if you're nailing the move or if there's still work to be done.
1. Using momentum
'Most commonly, people swing their arms too quickly when performing this movement, but this isn’t actually working your muscles,' says Wiener. 'Instead, it creates momentum and feels easier to lift the weight. So, make sure the movement is slow and controlled to get the most out of this exercise.'
2. Letting your elbows flare out
This transfers some of the tension away from your arms and onto your shoulders and/or back. Keep your elbows close to your sides, in front of your hips.
3. Not getting the full range of motion
Make sure your arm is fully straight at the bottom of the rep and that you're squeezing your bicep as hard as possible at the top.
4 Hammer curl variations and alternatives
1. Cross-body hammer curl
A) Stand upright with your hands by the side of your body with palms facing inwards, holding one dumbbell in each hand with a neutral grip.
B) Keeping your upper arm by your side, raise one dumbbell up towards your opposite shoulder. Don't swing the dumbbell. Pause at the top of the rep.
C) Lower the dumbbell back down, returning to the starting position.
D) Repeat on the other side
2. Cable rope hammer curl
Using cables will help you to maintain tension throughout the movement, maximising the amount of time your muscles are engaged.
A) Attach a rope handle to a cable pulley machine.
B) Grasp the rope with a neutral (palms facing each other) grip and stand straight up. Keep your elbows by your side.
C) Bend your elbows, and, using your biceps, pull your arms up until your biceps touch your forearms. Don't let your elbows flare. Hold for one second at the top and slowly lower back to the starting position.
3. Preacher hammer curl
A) Stand or sit at a preacher (sloping) bench with your arms resting of the sloping surface in an extended position.
B) Holding the dumbbells in a neutral grip, bend your elbows and curl the weight towards your shoulders, squeezing your biceps at the top and pausing for a second.
C) Lower your weights to the starting position.
4. Neutral grip pull-up
These work the biceps and forearms, and, like a hammer curl, put less strain on the wrist than traditional pull-ups.
A) Step up to a parallel pull-up bar. Use a neutral grip so that your palms face inward.
B) Hang from the bar with your arms straight. Keep your hips, core and legs in a slight hollow position,
C) Bend your arms and pull your bodyweight towards the bar, until your chin is over the bar. Release your arms and return to a hanging position.
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