Training guide
A hammer curl is a dumbbell curl with your palms facing your body and your thumbs pointing up the whole way, as if you were swinging a hammer. It works the same three muscles as any curl: the biceps, the brachialis underneath it and the brachioradialis in your forearm. Most people can lift about as much as they do palms up.
What the grip changes is smaller than most guides say, and the studies disagree. Curling without a weight, the grip made no difference to the biceps; curling a heavy cable, palms-up curls worked both the biceps and the forearm's brachioradialis a little harder than a rope hammer grip. No trial has compared the grips for growth.
This guide covers the hammer curl step by step on the 3D figure, what it works, hammer curls against bicep curls, how heavy to go, sets and reps, the versions, and your elbows and wrists.
Hold a dumbbell in each hand at your sides with your palms facing your thighs. Keeping your elbows by your sides and your wrists straight, curl the weights up towards the front of your shoulders with your thumbs pointing up the whole way, then lower them until your arms are straight. The American Council on Exercise (ACE) rates it an intermediate exercise.
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The biceps, the brachialis underneath it and the brachioradialis in your forearm all bend the elbow. In an MRI (magnetic resonance imaging) study of 4 men, the brachialis provided 47% of the elbow-bending force, the biceps 34% and the brachioradialis 19%.
Curling without a weight, 16 adults' biceps worked the same in every grip, and their brachioradialis worked harder only with the palm down. Curling a heavy cable, 10 bodybuilders' biceps worked 12% harder palms up than with a rope hammer grip, and their brachioradialis about 6% harder. So "hammer curls target the forearm" isn't shown.
In 11 men, the most force they could produce bending the elbow was 243.6 newtons with the thumb up and 213.6 palms up, not significantly different, against 113.6 palms down. Most people can hammer curl about what they curl palms up.
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A weight you can curl 10 to 15 times without swinging, for 2 or 3 sets, with the last set 0 to 2 reps short of failure, as in our workouts. For bigger arms, aim for about 10 or more hard sets a week for the elbow muscles, counting each set of rows or pulldowns as half a set.
Many people find the thumb-up grip the most comfortable curl for sore elbows, and our elbow guides use it that way. With pain on the thumb side of the wrist, curl palms up instead. A pop at the front of the elbow with bruising and a bulge in the upper arm needs checking the same day.
A curl with your forearm in the neutral position, thumbs up and palms facing in, the whole way up and down. ACE notes that some people's elbows are built so they can't hold the dumbbells against their sides without bending their wrists: choose the most comfortable position that keeps your wrists straight.
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Its two heads attach to the radius, the forearm bone on the thumb side, just below the elbow. It bends the elbow and, with the elbow bent, it's the forearm's strongest palm-up turner.
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It lies deeper than the biceps and bends the elbow in every hand position: "a pure flexor". It attaches to the ulna rather than the radius, so turning your forearm doesn't change its pull, and only fine-wire electrodes can record it, not the usual surface ones. Claims that hammer curls single it out haven't been measured.
The long muscle on the thumb side of your forearm. It bends the elbow and helps turn the forearm both ways, back towards thumb up from palm up or palm down.
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Grip comparisons use EMG (electromyography: electrodes measuring how hard a muscle works in a few reps). EMG isn't a validated predictor of what a muscle builds over months.
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Curling with no weight at a slow, steady speed, 16 adults' biceps activity didn't change with the palm up, in or down, and the brachioradialis worked harder only with the palm down. Curling their own 8-repetition maximum on a cable (a bar for palms up and palms down, a rope for the hammer grip), 10 competitive bodybuilders' biceps worked harder palms up than with the hammer grip (12% more) or palms down (19% more), and their brachioradialis worked harder palms up than hammer (6% more) or palms down (5% more); neither muscle differed while lowering. Holding just 1 kg, 36 men's biceps were more active palm up and their brachioradialis palm down at most elbow angles. All small, and none measured growth.
In 11 men, maximal elbow-bending force was 243.6 newtons with the forearm neutral, 213.6 palm up and 113.6 palm down. Neutral and palm up didn't differ significantly, and both were clearly stronger than palm down.
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We found no trial comparing hammer and palms-up curls for growth. Ordinary curls grow the deep and forearm muscles too: in 21 untrained adults, 12 weeks of incline or preacher dumbbell curls (5 sets of 10, twice a week) grew the brachioradialis by 13.5% and 17.6% and the brachialis by 17.1% and 21.1%, measured by MRI. The study's summary doesn't say which grip they used.
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In 585 adults who trained one arm the same way for 12 weeks, biceps size changed by anything from a 2% loss to a 59% gain. Men gained slightly more in absolute size, and women more in relative strength.
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More weekly sets built more muscle, with returns shrinking as the sets go up. The American College of Sports Medicine's (ACSM's) overview of 137 reviews found growth enhanced with 10 or more sets a week, and across 67 studies, counting indirect sets, such as rows for the elbow muscles, as half sets predicted growth best.
Across 15 studies, training to failure gave a trivial growth advantage at most, and across 28 studies of 747 adults, light, moderate and heavy loads built similar muscle when sets were hard.
Steps from ACE's hammer curl and our move page; the count of 2 and the stopping rule follow our bicep curl guide.
Loading the 3D figure…
The movement on the figure: Hammer curl
Under a heavy load, palms-up curls worked the biceps and the brachioradialis a little harder, and the front of the shoulder worked harder with the hammer and palms-down grips. Without a load, the grip made no difference to the biceps. The two studies disagree, so neither grip has a proven edge.
You can lift about the same, and all three elbow muscles work in both; the brachialis bends the elbow whatever your grip.
Neither has been shown to build more arm muscle. Use whichever suits your wrists and elbows, or both; our bicep curl guide covers the palms-up curl and compares the two from its side.
Count every curl the same towards your weekly sets for the elbow muscles, whatever the grip.
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2 or 3 sets of 10 to 15, with the last set 0 to 2 reps short of failure, as in our workouts: 2 sets in the upper body and pull day workouts, 3 in the arm workouts. In your first two weeks, leave 3 or 4 reps to spare, as our plans advise.
60 to 90 seconds. Pairing each set with a triceps move saves time, as our arm workouts do.
About 10 or more hard sets a week for the elbow muscles, counting each set of rows, pulldowns or chin-ups as half a set, as our bicep curl guide does. Hammer curls count the same as any curl.
Two or three sessions a week. For growth, the number of hard sets in a week mattered more than how often they were done.
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Start with about what you'd curl palms up for 10 to 15 reps. Add reps before weight: dumbbell jumps are big for curls, so reach 15 on every set before you take the next dumbbell (our editorial suggestion, as in our bicep curl guide).
The NHS strength routine curls light weights, and filled water bottles will do: 3 sets of 5 with each arm. Thumbs up or palms up both work (our view).
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Go lighter and keep your body upright.
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Keep them by your sides, and stop when your forearms are about upright.
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Keep each wrist straight, in line with your forearm.
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Keep your thumbs up the whole way, up and down.
Keep your shoulders down and relaxed.
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Straighten your arms every rep: across 11 studies, full range and the stretched part of the range grew the biceps and brachialis more than partial reps near the top.
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2 or 3 sets of 10 to 15 (our editorial starting point; these move pages give no dose), except the cross-body curl, 2 to 3 sets of 8 to 12 with each arm (its move page). The cross-body hammer curl has no 3D demo yet: the alternating curl shows the movement; curl each dumbbell up and across towards the opposite shoulder.
3D demoHammer curlBeginner · A dumbbell
3D demoAlternating hammer curlIntermediate · A dumbbell
3D demoCable rope hammer curlBeginner · A cable machine
3D demoIncline hammer curlIntermediate · A dumbbell + A bench or box
3D demoPreacher hammer curlIntermediate · A dumbbell + A bench or box
Cross-body hammer curlIntermediate · A dumbbellReverse curls, 2 sets of 10 to 15 and light (our editorial starting point), and Zottman curls, 2 to 3 sets of 8 to 12 (its move page), load the brachioradialis with a palm-down grip; with tennis elbow, bring reverse curls back last. Wrist curls both ways, forearm rotations and farmer's carries follow our grip strength workout.
3D demoDumbbell reverse curlIntermediate · A dumbbell
3D demoZottman curlIntermediate · A dumbbell
3D demoWrist curlsBeginner · A dumbbell
3D demoReverse wrist curlBeginner · A dumbbell + A bench or box
3D demoDumbbell forearm rotationBeginner · A dumbbell + A bench or box
3D demoFarmer's carryIntermediate · A dumbbell + A kettlebellDiscomfort up to about 3 to 4 out of 10 is fine if it settles within an hour and your elbow is no worse the next morning; otherwise go lighter, not to nothing, as our elbow guides say.
Tennis elbow pain is worse when lifting, bending the arm or gripping. Our elbow guides use the thumb-up grip as the gentler curl while it settles, and bring palm-down curls back last. See a GP if it hasn't improved after at least 2 weeks of self-care, as the NHS advises.
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Pain along the thumb side of the wrist that's worse when you lift with your thumbs pointing up, as in lifting a child, is typical of de Quervain's. Curl palms up instead while it settles, as our move page advises.
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A pop at the front of the elbow, with severe pain, bruising, weak palm-up turning and a bulge in the upper arm, can be a torn biceps tendon. It's uncommon, about 3 to 5 people per 100,000 a year, but it's best repaired within the first 2 to 3 weeks. Sudden sharp pain in the upper arm with a "Popeye" bulge is usually a tear at the shoulder, which most people manage without surgery.
Or a heart or lung transplant: follow your surgeon's limits before lifting with your arms, as our move pages and heart surgery guide say.
Our forearm workout leads with hammer, reverse and Zottman curls. The arm workouts pair hammer curls with a triceps move for 3 rounds of 10 to 15 (10 to 12 in the gym version), the upper body and pull day workouts use 2 sets of 10 to 15, and the grip strength workout trains your hands and wrists.
A 25-minute forearm size workout with dumbbells: hammer, reverse and Zottman curls for the big muscle on the thumb side, then wrist curls and a carry.
25 minBeginner7 movesA dumbbell, A kettlebellA 30-minute arm workout at home with dumbbells: curls, hammer curls and concentration curls paired with overhead extensions, close-grip push-ups and kickbacks.
30 minBeginner8 movesA dumbbellBiceps, triceps and forearms: curls, hammer curls, skull crushers, pushdowns, concentration curls and dips.
35 minBeginner7 movesA dumbbell, A bench or boxUpper body workout B: overhead press, pull-ups, incline dumbbell press, chest-supported rows, face pulls, hammer curls and triceps extensions.
50 minIntermediate13 movesA band, Pull-up barDumbbell upper body workout B: incline presses, chest-supported rows, seated presses, lateral raises, reverse flyes, hammer curls and skull crushers.
45 minIntermediate11 movesA dumbbell, A bench or boxA pull day workout for back and biceps: pull-ups, barbell rows, chest-supported rows, face pulls and curls, with sets, reps and rest.
55 minIntermediate10 movesPull-up bar, A barbellAn upper body workout at home with no gym: push-ups, band rows, pike push-ups, face pulls, close-grip push-ups and Y-T-W raises, with dumbbell options.
30 minIntermediate13 movesA band, An anchor pointA 20-minute grip session: warm up the wrists and fingers, train the hand and forearm muscles, then carry and hang to load your grip the way everyday life does.
20 minBeginner10 movesOther / check instructions, A bandHammer curls come round once or twice a week in each of these plans; the bro split gives them a whole arm day.
The classic chest, back, legs, shoulders and arms week, built from our gym workouts, with what research says about training each muscle once.
5 training days45 minIntermediate4 days a weekA 4-day upper/lower split: two upper body and two lower body gym days, each muscle trained twice a week, with sets, reps and progression.
4 training days50 minIntermediate5 days a weekA 5-day gym split that trains every muscle twice a week: upper, lower, push, pull and legs, with an honest look at the bro split.
5 training days50 minIntermediate6 days a weekA 6-day push/pull/legs plan for experienced lifters: two push, two pull and two leg days, with sets, reps, rest and lighter weeks.
6 training days55 minAdvanced4 days a weekA 4-day dumbbell-only plan for home or gym: two upper and two lower days, every set, rep and rest, and how to keep progressing when the dumbbells max out.
4 training days45 minBeginner4 days a weekA 4-day gym workout routine for men: upper and lower days, each muscle trained twice a week, with sets, reps, progression and the evidence.
4 training days50 minIntermediateIf you get chest pain or pressure, feel faint or dizzy, are unusually breathless, or your heart races or beats irregularly during exercise, as our plans advise. The American Heart Association says these need immediate medical evaluation.
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If arm pain comes on suddenly with pressure, heaviness or squeezing across your chest.
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For severe pain in your arm that makes it difficult to move; an injury with a snap, or an arm that has changed shape; or an arm that tingles or feels numb. For a pop at the front of the elbow with bruising and a bulge in the upper arm: don't wait for it to settle, because a torn biceps tendon is best repaired within the first 2 to 3 weeks. In the US, go to urgent care or the emergency department.
For a sudden pop or snap with pain at the shoulder or upper arm during a lift, with or without a bulge low in the upper arm, as our biceps tendinitis guide advises.
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If your arm hurts when you exercise but the pain eases when you rest; if it's swollen and you have a very high temperature or feel hot, cold or shivery; if you think you've torn a tendon; or for severe wrist pain, a snap or popping when it happened, a wrist you can't move or hold things with, or lost feeling in your hand. In the US, contact your doctor or urgent care.
If elbow or arm pain hasn't gone after a few weeks; if tennis elbow hasn't improved after 2 weeks of self-care; or if wrist pain is stopping your normal activities, getting worse, not improved after 2 weeks, or comes with tingling in your hand.
Very painful, swollen, tight arms and dark urine after an unusually hard or high-rep session need medical help the same day: it could be rhabdomyolysis, as our elbow pain from pull-ups guide explains.
No study has tested it. Under a heavy load the biceps worked less with the hammer grip than palms up, muscle activity in a set doesn't reliably predict growth, and people's arms respond to the same training very differently.
We found no study that separated the biceps' two heads by grip. In the loaded study, the electrodes couldn't tell the heads apart, so its results describe the biceps as a whole.
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The brachialis bends the elbow in every grip and can only be recorded with fine wires, not the usual surface electrodes. No growth trial compares grips, and ordinary incline and preacher curls grew the brachialis by 17.1% and 21.1% in 12 weeks.
Curling without a weight, the brachioradialis worked harder only palms down; curling a heavy cable, slightly harder palms up; holding 1 kg, more palms down. Hammer curls train it, as other curls do: mix grips if forearm size is your goal.
We found no study of it. Weekly hard sets drive growth, with returns shrinking as the sets go up, so a few hard sets two or three times a week does the job.
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We found no trial of hammer curls as a treatment. Our elbow guides use the thumb-up grip as the gentler curl while the elbow settles, and our tennis elbow guide has the plan.
Hold a dumbbell in each hand at your sides, palms facing your thighs. Keeping your elbows by your sides and your wrists straight, curl the weights towards the front of your shoulders with your thumbs up, then lower them slowly until your arms are straight.
The same three as any curl: the biceps, the brachialis underneath it and the brachioradialis in your forearm. In an MRI study, the brachialis provided almost half of the elbow-bending force, the biceps about a third and the brachioradialis about a fifth.
Neither, for most people. Under a heavy load, palms-up curls worked the biceps 12% harder and the brachioradialis slightly harder than a hammer grip, while the two grips were about equally strong in another study. No trial has compared them for growth, so use both or whichever suits your wrists and elbows.
Yes: the brachioradialis, the big forearm muscle on the thumb side, bends the elbow in every curl, and ordinary dumbbell curls grew it by 13.5% to 17.6% in 12 weeks in one trial. The muscles that move your wrist and close your hand need wrist curls and carries as well.
They train the biceps as any curl does, but no study shows they build a wider arm or a bigger peak. Under a heavy load the biceps actually worked a little less with the hammer grip than palms up, and people's arms respond to training very differently.
We found no study that separated the biceps' two heads by grip, and in the loaded study the electrodes couldn't tell them apart. Claims that hammer curls target one head are untested.
A weight you can curl 10 to 15 times without swinging, with the last set ending 0 to 2 reps short of failure. Most people can hammer curl about what they curl palms up: in one study the two grips were about equally strong, and both about twice as strong as palms down.
Two or 3 sets of 10 to 15, with 60 to 90 seconds' rest. For bigger arms, aim for about 10 hard sets a week for the elbow muscles across all your curls, counting rows and pulldowns as half sets.
You can, but you don't need to: for growth, weekly hard sets mattered more than how often they were done. We found no study of "100 hammer curls a day", and repetitive, forceful arm work raises the odds of tennis elbow in workers, so build up gradually.
Many people find the thumb-up grip the most comfortable curl while the outer elbow settles, and our elbow guides use it that way, keeping discomfort to about 3 to 4 out of 10. They aren't a treatment on their own; see a GP if tennis elbow hasn't improved after 2 weeks of self-care.
Pain on the thumb side of the wrist when you lift with your thumbs pointing up is typical of de Quervain's. Curl palms up instead while it settles, and see a GP if wrist pain stops your normal activities, gets worse or hasn't improved after 2 weeks.
They train the same muscles. The cross-body version curls each dumbbell across towards the opposite shoulder, and the rope on a low cable lets you add weight in small steps; the loaded study's hammer grip used a rope. Sitting on a bench stops any swing.
Exercise education, not a personal prescription, and clinical review of these guides is pending. Check with a GP before starting hard training if you have a heart condition, chest pain, dizziness or breathlessness when active, and stop for sharp or increasing pain. Health disclaimer.
