reckonerMachine biceps curl
A seated curl with your upper arms resting on a pad, so the elbow is the only joint that moves and the weight cannot swing. Because the pad holds you in place, what you log is what the arms lifted. The part people skip is the bottom of the range, and a trial on the seated preacher curl found it was worth keeping1.
Elbows at the pivot, lower all the way.
- Pattern
- Arm isolation
- Trains
- Biceps
- Kit
- Machine biceps curl
- Loading
- A weight you choose
- Reckoner prescribes
- 3 sets of 10 to 15 reps at RPE 8
- Progression step
- 5 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
Match your elbows to the pivot
Set the seat so your elbows line up with the machine's pivot. If the pivot sits above or below your elbow, the pad slides your arm through the rep instead of letting it turn.
Rest the whole upper arm on the pad
The upper arms lie flat on the pad with the armpits near its top edge, and your hands take the handles. Nothing above the elbow should be able to help.
Curl up without lifting the shoulders
Bring the handles toward you by bending the elbows and keep the shoulders down and still. Stop when the arms are fully bent and squeeze for a beat.
Lower until the arms are almost straight
Let the handles back slowly, all the way to a nearly straight arm, and keep the stack off its rest between reps. This is the lowest part of the range, the one the pad makes easiest to skip.
What goes wrong
Stopping a long way short of straight
The pad makes the bottom of the rep the uncomfortable part, so people stop at a tidy right angle and add weight. In a trial of 19 young women on a seated preacher curl, the arm that trained only the straighter half of the movement grew the part of the biceps nearer the elbow more than the arm that trained only the bent half1.
Lifting the chest or sliding the hips
Moving the body lets the elbow travel further than the pad intended and puts the load on the body's momentum. The number you log then belongs to the body, not to the arm.
Dropping the handles from the top
A fast drop turns the lowering half of the rep into a free fall, so the muscle works for half of what the set counts as. Let it come back at a pace you could stop.
How Reckoner progresses this lift
Six weeks of this lift, 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 | More reps 10 → 11 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 2 | 3 x 11 | More reps 11 → 12 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 3 | 3 x 12 | More reps 12 → 13 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 4 | 3 x 13 | More reps 13 → 14 repsYou finished every set with three reps left in the tank (RPE 7) and room left in the range, so the reps climb before the load does. |
| 5 | 3 x 14 | 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 | More reps 14 → 15 repsYou finished every set with three reps left in the tank (RPE 7) and 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
Is a machine curl as good as a dumbbell curl?
The comparison that has been run is between dumbbell curls with the arm in front of you on a preacher pad and with the arm behind you on an incline bench. After 12 weeks in 21 untrained adults, total elbow flexor growth did not differ between them, the preacher curl grew the brachialis and brachioradialis more, and the incline curl grew the biceps more2. It was dumbbells and not this machine, so read it as a statement about the arm position.
Does a machine do worse than free weights for the arms?
For muscle size the evidence does not separate them. A meta-analysis of thirteen studies found no difference in hypertrophy between free weight and machine training, and found strength gains specific to the kind of test used3.
Will Reckoner put this machine in my plan?
Not by itself, and on purpose. The engine never places this machine for you: you reach it by choosing it in a swap or in the movement picker, and a lane you have put it on keeps it. Once it is on your plan, the engine reads the sets you log on it the way it reads any other lift.
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
- Pedrosa and colleagues, Sports, 2023. Training in the initial range of motion promotes greater muscle adaptations than at final in the arm curl 19 young women training one arm in the straighter half and one in the bent half of a seated dumbbell preacher curl for eight weeks, with greater biceps growth at 70 per cent of the muscle's length for the straighter half
- Kobayashi and colleagues, Journal of Sports Sciences, 2026. Exercise-specific preferential hypertrophy of individual elbow flexor muscles after incline versus preacher dumbbell curl training 21 untrained adults training one arm with incline curls and one with preacher curls for 12 weeks, with no difference in total elbow flexor growth and small differences between individual muscles
- Haugen and colleagues, BMC Sports Science, Medicine and Rehabilitation, 2023. Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance: a systematic review and meta-analysis thirteen studies and 1016 participants comparing free weight with machine training for at least six weeks, with no difference between the two in muscle hypertrophy and strength gains specific to the kind of test used