Bayesian Curl: How to Do the Bayesian Cable Curl Properly

The Bayesian curl is a single-arm cable curl where you stand facing away from a low pulley and let the cable pull your arm a little behind your body. That shoulder position stretches the biceps before you curl, and the cable keeps tension on the muscle at the bottom of the rep, which is exactly where a standing dumbbell curl goes light. It takes about a minute to set up on any adjustable pulley, it's easy on the elbows, and it's one of the few curls that challenges you hardest in the stretched position.

The name isn't about statistics. It comes from Bayesian Bodybuilding, the coaching business run by Menno Henselmans, who popularised the movement. Here's how to do it well, what the research says about long-length training for the arms, and how to fit it into a programme.

How to do a Bayesian curl

You need a cable station with a pulley you can set low, a single D-handle, and enough floor in front of the stack to take a step or two.

1. Set the pulley. Move the carriage to roughly hip height or just below. On a machine with only a fixed low pulley, the bottom position works too; the angle just gets a bit steeper.
2. Turn your back to the stack. Grip the handle with your working hand, palm facing forward, and walk one to two steps away until the weight lifts off the stack with your arm hanging behind you.
3. Stagger your stance. Put the leg on the same side as your working arm behind you and the other forward. A split stance stops the cable pulling you backwards and keeps your torso steady.
4. Find the start position. Let the cable draw your upper arm back until your elbow sits slightly behind your torso and your arm is straight. You should feel a stretch through the front of the upper arm and shoulder, not a pinch.
5. Curl. Bend at the elbow and bring the handle up towards your shoulder, keeping the upper arm where it is. Squeeze for a moment at the top.
6. Lower slowly. Take two to three seconds to return to a fully straight arm, then let the stretch settle for half a second before the next rep.

Do all your reps on one arm, then switch. Start with your weaker side and match the reps on your stronger side.

Form cues worth repeating to yourself

• Chest up, shoulder down. Don't let the front of the shoulder roll forward at the bottom. Think about keeping your chest proud and the shoulder blade lightly pulled back.
• Straighten fully. The bottom few degrees of elbow extension are where most of the benefit lives, so don't cut them short to move more weight.
• Lean slightly forward if you need to. A small forward lean from the hips increases the shoulder stretch without forcing the joint. Most people do best with 10 to 20 degrees of lean.

Why the stretched position matters

There's a growing body of research suggesting that muscles grow well when they're loaded hard at long lengths. For the biceps, a long length means the elbow nearly straight, and the long head of the biceps (which crosses the shoulder) gets stretched further when the arm sits behind the body.

The most cited elbow flexor study here is from Pedrosa and colleagues. Nineteen untrained women trained one arm through only the first part of a preacher curl (elbow nearly straight to about 68 degrees) and the other arm through only the top half. After 8 weeks, the stretched-range arm showed more growth in the lower part of the biceps and bigger gains in full-range one-rep max strength, while growth at the mid-point of the muscle was similar (Pedrosa et al. 2023). A 2026 review by the same lead author draws the practical line clearly: long-length training seems to give better growth when the exercise puts real resistance on the muscle in the lengthened position (Pedrosa et al. 2026).

That second point is where the Bayesian curl earns its place. A free-weight standing curl has almost no resistance when your arm hangs straight, because gravity pulls the dumbbell straight down through your elbow. The cable in a Bayesian curl pulls back along your forearm instead, so the bottom of the rep is genuinely hard.

Now the honest caveat. A 2026 within-participant trial tested whether the shoulder angle itself made a difference. Untrained men did unilateral cable curls to failure for 10 weeks, with one arm at maximum shoulder extension (the Bayesian position) and the other arm neutral, and the resistance profile and elbow range were matched. Both arms grew by roughly 7 to 9 percent and the difference was close to zero (shoulder extension angle trial, 2026).

So the shoulder stretch isn't magic on its own. What matters more is that you're loading a nearly straight elbow through a full range and pushing sets close to failure. The Bayesian curl happens to make that easy, which is a good reason to use it. It's not a reason to drop every other curl.

Muscles worked

• Biceps brachii. Both heads work, with the long head taken to a longer length than in most curls because of the shoulder position. Our long head bicep exercises guide covers other ways to bias it.
• Brachialis. This deeper elbow flexor sits under the biceps and works in every curl. A neutral grip shifts more work onto it and the brachioradialis, which is the main idea behind our hammer curl vs bicep curl comparison.
• Forearm flexors and grip. They hold the handle, though at the loads you'll use this isn't much of a grip challenge.

Common mistakes

Letting the elbow swing forward. This is the big one. As fatigue builds, the shoulder flexes to help the curl, and the elbow ends up in front of your body by the top. Lighten the load until you can finish every rep with the elbow still behind you.

Standing too close to the stack. If the weight touches down at the bottom of each rep, you lose tension in the stretched position. Take another half-step forward.

Forcing the shoulder stretch. The front of the shoulder should feel stretched, never sharp or pinchy. If it does, reduce how far back the arm goes or raise the pulley a notch. People with a history of front shoulder or biceps tendon trouble should ease in with very light weights.

Short reps at the bottom. Stopping two-thirds of the way down to keep the set going removes most of the reason to do this exercise. Straighten the arm every time.

Going too heavy. You're weakest at the start of the rep, so the weight you can control is smaller than on almost any other curl. That's fine.

Variations

Single-arm standing Bayesian curl. The standard version above. It's the one to learn first.

Kneeling Bayesian curl. Kneel on one knee facing away from a low pulley, with the pulley set right at the bottom of the column. Kneeling takes the legs and hips out of it, which makes cheating with body English much harder, and it's handy when your machine only has a fixed low pulley because the lower body position fixes the cable angle.

Bayesian curl with a band. For home training, anchor a loop band low behind you (a door anchor at the bottom of a closed door works, or a heavy rack upright) and step forward until there's tension with your arm straight. Bands get harder as they stretch, so the bottom of the rep is lighter than on a cable, which is the opposite of what you want. Step further away to add tension at the start, and pair it with an incline dumbbell curl on the same day to cover the stretched range properly. Our best resistance bands UK guide covers sets with door anchors.

Dual-cable Bayesian curl. Stand in the middle of a cable crossover with both handles and curl both arms at once. It saves time but the stance is harder to stabilise, so most people get better reps one arm at a time.

Pair it with a spider curl. If you want a counterpart that loads the shortened position, a spider curl is the natural opposite: chest on an incline bench, arms hanging in front, hardest at the top. Doing one of each is a simple way to cover the whole strength curve. If you're looking to replace preacher curls specifically, see our preacher curl alternative list.

Programming the Bayesian curl

Treat it as an accessory and put it after your main pulling work, such as rows or pulldowns, when your biceps are already warm.

• For muscle growth: 2 to 4 sets of 10 to 15 reps per arm, taken to within 1 or 2 reps of failure. Rest 60 to 90 seconds between arms.
• Weekly volume: if it's your only curl, 6 to 8 hard sets a week split across two sessions is a reasonable target (the 2026 trial used six to eight weekly sets). If you also do incline or hammer curls, 2 or 3 Bayesian sets per session is plenty.
• Progression: add reps first, then add the smallest plate or pin increment your stack allows. Cable stacks often jump in 5kg steps, which is a lot for a single-arm curl; a set of add-on weights or simply adding reps works better.

A sample arm day might be 3 sets of Bayesian curls, 2 sets of spider curls and 2 sets of hammer curls, which hits the stretched, shortened and neutral-grip positions with about seven sets in total.

Equipment

Any cable machine with an adjustable or low pulley will do. Gyms almost always have one. At home, a dual adjustable tower such as the Bells of Steel Cable Tower handles Bayesian curls at any height, and our best cable machine UK guide compares compact options by price and footprint. If you're building a full setup, our home gym hub collects everything in one place. For more cable curl options, including straight bar, rope and high-cable versions, see our cable bicep curl guide.

Recommended reads

1. Incline dumbbell curl: form and benefits
2. Spider curl: how to do it
3. Hammer curl vs bicep curl
4. Preacher curl alternatives
5. The best cable machines in the UK