reckonerDumbbell hammer curl
Thumbs up, palms facing each other, elbows at your sides. The hammer curl is usually sold as the forearm builder, and the measurement does not back that as cleanly as the claim suggests. It is still worth doing, for a plainer reason.
Thumbs up, elbows pinned to the sides.
- Pattern
- Arm isolation
- Trains
- Biceps, forearms
- Kit
- Dumbbell
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 10 to 15 reps at RPE 8
- Progression step
- 1 kg once the top of the range is clean
- Skill
- Simple to learn
- Recovery cost
- Very low
- Not prescribed if you have declared
- Elbow
Muscles worked
How to do it
Hold the bells like hammers
Palms facing each other, thumbs on top, wrists straight and firm. Thumbs up, elbows pinned to the sides, which is the cue on your wrist.
Curl straight up, no rotation
Bring the bell up towards your shoulder with the palm staying inward the whole way. If the hand starts turning, that is a normal curl with extra steps.
Stop before the elbow lifts
Finish with the forearm a little past vertical. The elbow stays pinned against your ribs from the first rep to the last, and the moment it travels the shoulder has taken over.
Lower slowly to a straight arm
Three seconds down, elbow fully open at the bottom, and the palm still facing in. Full range beats a shortened one on every pooled outcome2.
What goes wrong
Believing the neutral grip loads the forearm harder
When ten trained lifters curled a cable with supinated, neutral and pronated grips, the brachioradialis was more excited with the palms fully up than with either of the other two, and so was the biceps brachii1. Those are the two muscles the study measured, and neither of them preferred the neutral grip.
Going much heavier because it feels stronger
A hammer curl usually does allow a slightly heavier bell, and that invites a swing. The elbow position is what makes it work, and it is the first thing a heavy bell takes away.
Letting the wrists collapse
A soft wrist under a heavy bell tips backwards at the bottom and does nothing but hurt. Grip hard and keep the knuckles in line with the forearm.
How Reckoner progresses this lift
Six weeks of this lift, from 14 kg, run through the real engine. Nothing below was typed in: the prescription, the decision and the sentence beside it all come from the same code that writes your week.
| Week | Prescribed | What it did |
|---|---|---|
| 1 | 3 x 10 at 14 kg | More reps 10 → 11 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 2 | 3 x 11 at 14 kg | More reps 11 → 12 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 3 | 3 x 12 at 14 kg | More reps 12 → 13 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 4 | 3 x 13 at 14 kg | More reps 13 → 14 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. |
| 5 | 3 x 14 at 14 kg | Deload 40% of sets offFive weeks of building, then one week lighter. About 40% of the sets come off. The load holds and your reps stay where you earned them, so you keep the strength and lose the fatigue. |
| 6 | 2 x 14 at 14 kg | More reps 14 → 15 repsYou finished every set at RPE 7, with room left in the range, so the reps climb before the load does. The lighter week is over, so this is back to three sets. |
Real engine output, not an illustration. Every row was produced by running the engine itself when this page was generated.
The full rule, and why the reps move before the load does, is in how Reckoner decides to add weight.
Questions people ask
So why do a hammer curl at all?
Because it is a curl a lot of elbows and wrists tolerate better than a fully supinated one, and a set you can do without pain beats a marginally better set you cannot. Train the grip that lets you work hard.
Should I do these instead of normal curls or as well?
As well, if you have the sets to spend. More weekly sets keep buying more size and strength with shrinking returns3, so the honest question is what else those sets would have gone to.
Does Reckoner treat this as a different lift from a dumbbell curl?
It sits in the same lane as the other curls, so swapping between them keeps your history in one line. The load it prescribes will differ, because the grip does.
Similar movements
Reckoner eases the load first when this lift stalls, and offers one of these only if it stalls again after that. A lift already as light as your kit goes has no load left to ease, so the offer comes straight away. Each of them has a page.
Sources
- Coratella and colleagues, Sports, 2023. Biceps brachii and brachioradialis excitation in biceps curl exercise: different handgrips, different synergy ten competitive male bodybuilders curling a cable at an eight repetition maximum with supinated, neutral and pronated grips, with biceps brachii excitation in the lifting phase greater with the supinated grip than the neutral by twelve per cent and than the pronated by nineteen, and brachioradialis excitation also greater with the supinated grip than either of the others, and no significant grip differences in the lowering phase
- Wolf and colleagues, International Journal of Strength and Conditioning, 2023. Partial vs full range of motion resistance training: a systematic review and meta-analysis a meta-analysis reporting a trivial standardized mean difference of 0.12 in favor of full range training, with every outcome favoring full range but all effects between trivial and small, and a subgroup suggesting partials held at long muscle lengths may match or beat full range for size
- Pelland and colleagues, Sports Medicine, 2025. The resistance training dose response: meta-regressions exploring the effects of weekly volume and frequency on muscle hypertrophy and strength gains sixty-seven studies and 2058 participants, with size and strength both rising as weekly set volume rises and both showing diminishing returns, and weekly frequency compatible with a negligible effect on size once volume is accounted for