Preacher Curl: How to Do It, Muscles Worked and Benefits

The preacher curl is a biceps curl you do with the back of your upper arm resting flat on an angled pad, which locks your elbow in place and removes any chance of swinging the weight up. That fixed position is the whole point. It strips out momentum so the biceps does the work on its own, and it loads the muscle hard in the stretched, bottom part of the rep where most curls go easy on you. You can do it with an EZ bar, a straight bar or a single dumbbell, on a dedicated preacher bench or the sloped backrest of an adjustable bench. Here is how to do a preacher curl with good form, the muscles it works, the benefits and the mistakes to avoid.

How to do a preacher curl

You need a preacher pad (or the angled backrest of a weight bench) and either an EZ bar, a straight bar or a dumbbell. Set the seat or your body so the top edge of the pad sits just under your armpit, with the whole back of your upper arm flat on the pad.

1. Set up. Sit or kneel with your chest against the top of the pad and the backs of your upper arms resting flat along it. Your armpits should be near the top edge so the pad supports the arm, not just the elbow.
2. Grip the weight. Take an underhand (palms up) grip on an EZ bar or straight bar, hands roughly shoulder-width apart, or hold a single dumbbell in one hand. Lift the weight off the rack and start with your arms almost straight but a slight bend kept in the elbow.
3. Curl up. Bend at the elbows and bring the weight towards your shoulders by squeezing the biceps. Keep your upper arms pinned to the pad the entire time, do not let your shoulders shrug or roll forward.
4. Squeeze at the top. Pause for a beat at the top and squeeze the biceps hard. Do not curl so far that your forearms go past vertical, as tension drops off once the weight is stacked over the elbow.
5. Lower slowly. Take 2 to 3 seconds to lower the weight under full control until your biceps is stretched, stopping just before the elbow locks out completely. That controlled lower into the stretch is where the growth happens.

Muscles worked

The preacher curl is one of the more focused biceps isolation moves, with a couple of helpers in the forearm.

• Biceps brachii (short head especially). The biceps is the two-headed muscle on the front of your upper arm and it is the main mover here, flexing the elbow as you curl. The biceps has a long (outer) head and a short (inner) head, both crossing the elbow (StatPearls biceps anatomy). Because your shoulder sits slightly forward over the pad, the preacher curl tends to emphasise the short, inner head.
• Brachialis. This muscle sits underneath the biceps and is a primary elbow flexor in its own right. It adds thickness to the upper arm and works hard on every curl, more so with an EZ bar, a neutral grip or a hammer-style hold.
• Brachioradialis. A forearm muscle that helps bend the elbow, particularly when your grip is neutral or your wrist is angled, as it often is on an EZ bar.
• Forearm flexors. The muscles of your forearm grip the bar or dumbbell and stabilise the wrist throughout the rep.

A study on how shoulder position changes biceps activity found the preacher curl produced high muscle activation through the early, stretched part of the movement (effect of shoulder position on biceps EMG). That is what makes the bottom of the rep so demanding and so effective. If you want to load these muscles steadily over time, a good EZ bar or a set of adjustable dumbbells lets you nudge the weight up in small steps.

Benefits

• It removes momentum completely. With your upper arms locked on the pad, you cannot swing, lean back or use your hips to help. The biceps has to do the job alone, which is why preacher curls feel harder than standing curls with the same weight.
• It trains the stretched position. The bottom of a preacher curl puts the biceps in a deep stretch under load, and loading a muscle while it is lengthened is a strong driver of growth. Few other curls hit this position as well.
• It is kind on technique. Because the bench fixes your arm angle, there is very little to get wrong once you are set up. That makes it a great pick for beginners learning to actually feel the biceps work rather than heaving the weight.
• It builds genuine arm size and strength. A few focused sets once or twice a week add real biceps and brachialis development. The NHS recommends muscle-strengthening work for all major muscle groups, the arms included, on at least 2 days a week.
• It exposes imbalances. Done one arm at a time with a dumbbell, the preacher curl quickly shows up a weaker side and lets you even it out, something a barbell can hide.

Common mistakes

Going too heavy. This is the big one. Too much weight makes your shoulders rock, your bum lift off the seat and the range of motion shrink. Drop the load until you can curl smoothly with your arms staying flat on the pad.

Bouncing out of the bottom. Dropping the weight fast and rebounding out of the stretch uses momentum and puts the elbow tendon under a nasty jolt. Lower slowly, pause, then curl. The stretched bottom position is the point of the exercise, so treat it with respect.

Snapping the elbow straight. Fully locking out a loaded elbow at the bottom hammers the joint and the biceps tendon. Stop just short of dead straight and keep a sliver of bend.

Shoulders rolling forward. If you shrug or hunch to help the weight up, you bring the front delts in and take work off the biceps. Keep your chest on the pad and your shoulders down and back.

Curling too far at the top. Once your forearms pass vertical, the weight stacks over your elbow and tension drops to almost nothing. Stop at the point of peak squeeze rather than yanking the bar all the way to your face.

Variations

Once the standard preacher curl feels solid, mix in these to keep progressing or to shift the emphasis.

• EZ bar preacher curl. The angled grip of an EZ bar keeps the wrists in a more natural position and lets you load a little more than a dumbbell. This is the default version in most gyms for a reason.
• Dumbbell preacher curl. Train one arm at a time with a single dumbbell to fix imbalances and give each biceps its own full range of motion. A set of adjustable dumbbells makes small jumps in weight easy.
• Preacher hammer curl. Hold a dumbbell with a neutral (thumbs-up) grip to shift more load onto the brachialis and brachioradialis for thicker-looking arms. It works the same muscles as standard hammer curls but with the arm fully supported.
• Spider curl. Lie chest-down on an incline bench with your arms hanging straight down and curl from there. It is a close cousin of the preacher curl that keeps constant tension on the biceps.
• Single-arm cable preacher curl. Run a cable to a low pulley and curl with your arm on the pad. The cable keeps even tension through the whole range, smoothing out the strength curve.

Sets and reps

A simple plan that works for most people:

• Size and strength: 3 to 4 sets of 8 to 12 reps, once or twice a week. Rest 60 to 90 seconds.
• Burn and detail work: 2 to 3 sets of 12 to 15 reps with a lighter weight and a slow lower, rest 45 to 60 seconds.
• Learning the move: 3 sets of 10 slow reps with a light weight, focusing on keeping your arms flat and feeling the biceps stretch and squeeze.

Add a small amount of weight only once you can hit the top of your rep range with clean form, no shoulder rock and a controlled lower on every rep. Preacher curls pair nicely with a pulling movement like the bent-over row on an upper-body or pull day, and slot in well as biceps finishers in plenty of the workout guides on the site.

Recommended reads

1. The best EZ curl bars in the UK
2. The best adjustable dumbbells in the UK
3. How to do hammer curls
4. More workout and exercise guides