Bicep curl variations: incline, spider, EZ-bar, Bayesian, cable, reverse and Zottman, and what the studies found

Every curl bends the elbow, so every curl works the same three muscles: the biceps, the brachialis underneath it, and the brachioradialis along the thumb side of the forearm. Two things change between versions: where your upper arm sits, out in front of you, at your side or drawn behind you, and which way your palms face.

This page puts the versions side by side, then covers how to do each one and what the studies found. The setups are practical descriptions; the findings are cited. Three curls have their own pages: the preacher curl, the concentration curl and the hammer curl. How many curls your week needs next to your rows and pull-ups is on the arm workout.

The versions at a glance

Arm in front or arm behind: what the trials found

Four training trials compared curls with the upper arm in different places. None put one position clearly ahead; where they differed, it was in which muscle, or which part of the arm, grew more:

• In 21 untrained adults over 12 weeks, one arm did incline dumbbell curls and the other preacher curls. Total elbow-flexor growth, measured by MRI, was 17.6% and 19.2%, not significantly different. The incline curl grew the biceps more, 22.1% against 18.9%; the preacher curl grew the brachialis more, 21.1% against 17.1%, and the brachioradialis, 17.6% against 13.5%.¹
• In 15 young men over ten weeks, a preacher-style cable curl and a Bayesian cable curl, with the arm behind the body and both set to load the arm the same way through the rep, grew the biceps and the brachialis, measured as muscle thickness by ultrasound, with no significant difference.²
• In 63 young women over eight weeks, split into a preacher group and an incline group, the incline curl thickened the arm more near the shoulder and the preacher curl more near the elbow. On each curl's strength test, the group that trained that curl gained more.³
• In 24 untrained men over ten weeks, cable curls with the upper arm drawn back as far as it went, or kept at the side, grew the elbow flexors by about 7% to 9% in muscle thickness, measured by ultrasound, either way.⁴

One activity study points the other way. In 11 men who had lifted at least three times a week for a year or more, a standing dumbbell curl drew more biceps activity than a Bayesian cable curl, each at 80% of its one-rep max.⁵ That was a few reps on one day, not growth over weeks, and in the growth trials above the arm-behind cable curl kept pace with a preacher-style cable curl.²

Incline dumbbell curl

Lie back on a bench set to an incline, a dumbbell in each hand, and let your arms hang down behind your body. Curl without letting your elbows swing forward, then lower until your arms are straight. In 22 men who had done strength training for at least a year, doing one light rep of each of three dumbbell curls, the incline curl and the plain dumbbell curl kept biceps activity high through the whole range, while the preacher curl's stayed high over only a short part of it.⁶ The bench angle is a practical choice, not a finding: a steeper bench draws your arms back less.

Spider curl

Lie chest down on an incline bench, arms hanging straight down toward the floor, and curl the dumbbells or a bar up toward your shoulders, keeping your upper arms still. No study of the spider curl was found for this page, so nothing here says what it does next to the other curls.

EZ-bar and straight-bar curl

An EZ bar is the bent bar; its angled grips turn your palms in a little. In 12 trained men with at least three years of lifting, each doing one set of ten at 65% of their max on each curl, an EZ bar produced more biceps and brachioradialis activity than dumbbells, and a straight bar beat dumbbells only in parts of the rep. The authors called the choice between the straight bar and the EZ bar a matter of comfort.⁷ Dumbbell vs barbell covers the wider choice.

Cable curl and Bayesian curl

A cable curl is the standing curl on a low pulley, with a bar or a single handle. The Bayesian curl is a one-arm cable curl done facing away from the low pulley, with the working elbow kept behind your body, the setup the activity study above used.⁵ In the growth trials, curling with the arm drawn back grew the elbow flexors about as much as curling with it at the side⁴ or in front.² As practical advice, not a finding: take a step forward from the stack so the cable pulls your arm back at the bottom, and keep your elbow still as you curl.

Reverse curl and Zottman curl

A reverse curl is a curl with your palms facing down, with a bar, dumbbells or a cable. Two small studies disagree about what it does for the brachioradialis:

• Palms down raised it. In 16 healthy adults bending the elbow slowly, the brachioradialis was more active palms down than palms up or thumbs up, while biceps activity stayed the same.⁸
• Palms up raised it a little more. In 10 male competitive bodybuilders curling an 8-rep-max load, the brachioradialis was about 5% more active palms up than palms down while lifting, and the biceps about 19% more.⁹

Neither trained anyone over weeks. A Zottman curl combines the two grips: curl up with your palms up, turn them down at the top, and lower palms down. No study of the Zottman curl was found for this page. As practical advice, not a finding: if you want the palms-down grip in your week, the reverse curl and the Zottman curl are two ways to get it, and the forearm workout shows where they go.

How many curls, and which

• Count them with your rows. Rows, pulldowns and pull-ups bend the elbows too; the arm workout shows how to count them.
• As a practical start: one curl version for 2 or 3 sets of 8 to 15, one to three reps short of failure, at the end of a pull or upper-body day. Add a second version, with the arm somewhere else or the palms turned, if you want more. This is practical advice, not a finding. (How to judge reps left.)
• Change the version for a block of weeks, not every session, so you can see the weight go up. (Progressive overload covers the options.)

Common questions

Which curl should you do?

One you can load and keep adding to. In the trials above, growth was similar whether the upper arm was in front, at the side or behind.¹²⁴ The differences were in which of the three muscles, or which part of the arm, grew a little more.

Bayesian curl or incline curl?

Both put the upper arm behind you. No study comparing the two directly was found for this page. Each held its own against a preacher-style curl: the incline curl in 21 untrained adults¹ and the Bayesian cable curl in 15 young men.²

EZ bar or straight bar?

The authors of the 12-man study called it a matter of comfort.⁷ As practical advice: use the grip you can hold comfortably for every set.

Spider curl or preacher curl?

No study of the spider curl was found for this page, so there's nothing to compare it against. The preacher curl has the trials.

If you'd rather not plan it alone

The curls are easy to learn; deciding which ones your week needs next to your rows and pull-ups, and when to change them, is the part a page can't do. Coaching is the version where your workouts live in Trainerize, built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one. Coaching to build muscle explains how that works, and here's how to apply. Otherwise: pick one curl from the table above, run it for the next four weeks, and write down the weight each session.