Preacher curl: the setup, the stretch at the bottom, and the incline curl compared

A preacher curl is a curl done with the backs of your upper arms resting on a sloped pad, so your arms sit out in front of your body and can't swing. It trains the three muscles that bend the elbow: the biceps, the brachialis underneath it, and the brachioradialis, which runs down the thumb side of the forearm. The pad also changes where the rep is hard. With a bar or a dumbbell, the bottom, with your arms nearly straight, is the difficult part, and the top is easy.

This page covers the setup, what the trials found about that bottom range, how the preacher curl compares with the incline curl, the versions, the faults, and the sets. How curls fit next to your rows, and how many direct arm sets a week needs, is on the arm workout; the thumbs-up grip is on hammer curls.

How to set up and do a preacher curl

1. Set the seat so your armpits sit snug against the top edge of the pad and the backs of your upper arms lie flat on it.
2. Take the weight palms up: an angled bar (an EZ bar) with both hands, a dumbbell in one hand, or the machine's handles.
3. Curl up until your forearms are close to vertical, keeping your upper arms on the pad.
4. Lower under control, taking about two seconds, until your arms are almost straight. That's one rep.

Stop the top of each rep just before your forearms pass vertical. Past that point, a bar or dumbbell hangs over your elbows and the arm muscles get a rest.

The stretch at the bottom

A preacher curl with free weights loads the arm hardest near the bottom, where the elbow flexors are longest. A 2023 trial describes it as the curl that puts the most strain on the part of the range where the arm muscles are most stretched,¹ and in 22 people doing one light rep, at 40% of a maximal effort, of each of three dumbbell curls, the preacher curl's biceps long-head activity peaked at the start of the lift and stayed high only over a short part of the range, while the incline curl and the plain dumbbell curl kept it high throughout.²

Does that bottom range matter for growth? Three trials trained it directly:

• Bottom half against top half. 19 untrained young women trained one arm through the bottom half of a seated dumbbell preacher curl, from straight to about 68 degrees of bend, and the other arm through the top half, for eight weeks. The bottom-half arm grew more biceps near the elbow and gained more strength in a full-range test; growth at mid-arm, and the two sites added together, was similar.³
• Bottom half against the full range. In 13 trained lifters, 11 men and 2 women, preacher curls through the bottom half and through the full range grew the arm similarly at mid-arm over eight weeks, with a trivial-to-small edge for the bottom half nearer the elbow and a negligible strength edge for the full range.⁴
• Bar against cable. In 35 untrained young adults, 25 men and 10 women, on a ten-week whole-body program, a barbell preacher curl, hardest with the elbows straight, and a cable preacher curl, hardest with the elbows bent, grew the biceps similarly, 8% and 7%. The barbell group gained more strength with the elbow nearly straight.⁵

The American College of Sports Medicine's 2026 position stand found too little data to say whether range of motion changes muscle growth.⁶ So the practical reading is simple: use the full range and don't cut the bottom short. Lower until your arms are almost straight on every rep. When the full reps run out at the end of a set, a few bottom-half reps are a reasonable way to keep going; they aren't an upgrade on full reps.

Preacher curl vs incline curl

The two curls are opposites at the shoulder: the preacher pad holds your upper arms in front of you, and an incline bench lets them hang behind you.⁷ Four trials compared them, or cable curls set up like them:

• In 21 untrained adults over 12 weeks, one arm did incline dumbbell curls and the other preacher curls, five sets of 10 twice a week. MRI showed total elbow-flexor growth of 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%.⁷
• 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.⁸
• In 38 recreationally trained women over nine weeks, only one site grew significantly, near the elbow in the preacher group, and the groups didn't differ from each other. The authors note that both groups were smaller than their own power calculation called for.¹
• In 15 young men over ten weeks, a preacher-style cable curl and a cable curl with the arm behind the body, set so both were loaded the same way through the rep, grew the biceps and the brachialis with no significant difference.⁹

Read together: in the one trial that measured each muscle by MRI, the total elbow-flexor growth didn't differ significantly between the two curls, with the incline curl leaning toward the biceps and the preacher curl toward the brachialis; one of the ultrasound trials found the preacher curl's growth nearer the elbow, and in another only the preacher group's elbow-side site grew, with no difference between groups. When the cable trial matched the load through the rep, the arm angle didn't seem to matter. That's the arm workout's reading too: the version matters less than the habit. Against a standing curl, no training trial turned up in a PubMed search for this page; the activity study above is the only comparison. If you want more than one curl, run the preacher curl in one block of weeks and an incline or standing curl in the next.

Bar, dumbbell, machine and cable

The common faults, and a fix for each

• Lifting your elbows off the pad. Your shoulders rise and the upper arms join in. Keep the backs of your arms on the pad from the first rep to the last.
• The seat at the wrong height. Too low and your arms slide down the pad; too high and you hunch over it. Your armpits belong on the top edge.
• Cutting the bottom short. It's where a preacher curl does most of its work, so lower until your arms are almost straight.
• Dropping into the bottom. Lower in about two seconds, rather than letting the weight pull your elbows straight.
• Curling with the wrists. Keep them straight, in line with your forearms. If they bend, the weight is too heavy.
• Curling through something that hurts. Sore the next day is normal; a sharp or lasting hurt in the elbow isn't. Stop, and see a doctor or a physical therapist.

Sets, reps and where it goes

• Two or three sets of 8 to 15, stopping with a rep or two in reserve, or closer: curls are a fine place to go near failure. (How to judge reps left.) The American College of Sports Medicine's 2026 position stand, which covers healthy adults, advises at least two sets per exercise.⁶
• After the rows and pulldowns, at the end of a pull day or an upper-body day, where the arm workout puts curls. Count it as a direct set for the elbow flexors.
• Paired with the triceps. A preacher curl and a tricep pushdown make an easy pair: one set of each, then rest.
• Add reps, then weight. When every set reaches 15 clean reps, add the smallest plates the bar takes and start again near 8. (Progressive overload covers how much.)

If you'd rather not plan it alone

A preacher curl is easy to learn; deciding how many direct arm sets your week can carry on top of the rows and presses is the part a page can't do. Coaching is the version where your workouts are 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: at your next pull or upper-body session, swap your usual curl for three sets of preacher curls and write down the weight.