What muscles do preacher curls work?

The preacher curl trains the elbow flexors: the biceps brachii, brachialis and brachioradialis. With the upper arm resting forward on the pad, the long head of the biceps starts slightly shorter than in a standing curl, which is why the preacher curl is often described as short-head biased. Both heads still work hard, so treat that as an emphasis, not isolation.

Why are preacher curls harder at the bottom?

Because the pad angles your upper arms forward, your forearms reach horizontal, where the weight is hardest to hold, early in the lift rather than halfway up as in a standing curl. That puts the hardest part of the rep in the lower half, when the biceps are still fairly lengthened, so control that part and use a lighter load than you would for standing curls.

Is an EZ bar or straight barbell better for preacher curls?

Most people find an EZ-curl bar more comfortable, because its angled grips let the wrists and forearms sit partly turned in rather than fully palms-up. A straight bar makes you supinate fully, which some lifters like and others feel in the wrists or elbows. Use whichever lets you keep the upper arm on the pad and the wrists straight without discomfort.

Should you fully lock out your elbows on preacher curls?

Lower until the arm is nearly straight, but keep the biceps working rather than letting the weight drop the elbow into a hard lockout. The bottom of the preacher curl is where the load is heavy and your arm is stretched, so a controlled stop just short of lockout is easier to repeat, especially on tired final reps.

How do preacher curls compare to spider curls?

Preacher curls place your upper body behind an angled pad, loading the biceps heavily in the stretched bottom position. Spider curls have you lie chest-down on an incline bench with your arms hanging straight down, so the rep is easiest at the bottom and hardest through the middle and upper part, when the biceps are shorter. Many lifters use both across a training block for that reason.

Preacher Curl: Form & Muscles Worked

Brace the upper arm on the pad, curl without lifting the elbow, and lower before the elbow loses control. Keep the range controlled, adjust the load when technique changes, and stop or seek qualified advice if an exercise causes persistent pain.

Short-Head Biceps Isolation and the Lengthened-Resistance Curve

The biceps brachii’s long head crosses the shoulder as well as the elbow, so its tension depends partly on shoulder position; the short head crosses only the elbow. Resting the upper arm on the preacher bench’s angled pad fixes the shoulder in a slightly flexed position, which starts the long head slightly shorter than in a standing curl where the upper arm hangs by your side. That is the usual reasoning for calling the preacher curl short-head biased. It is a sensible coaching idea, but both heads still contribute, so think of it as a small shift in emphasis rather than a different exercise.

The pad’s angle also changes where in the range the exercise is hardest. A standard standing curl is hardest near the middle of the range, where the forearm’s resistance arm from the elbow is largest, and easiest at the bottom, where the forearm hangs nearly in line with gravity. On a preacher bench the upper arm is angled forward, so the forearm is already close to horizontal near the bottom of the rep. The biceps therefore starts the lift lengthened and under meaningful load, rather than at the point where the weight is easiest. This is why the bottom of a preacher curl feels much harder than the bottom of a standing curl, and why lifters who cannot control that bottom position should shorten the range rather than force a dead-hang start.

Elbow Hyperextension Safety

Because the pad supports the upper arm and stops the torso from helping, the load can pull the elbow hard into a straight or overstraight position at the bottom, especially on the last tired reps of a set. Stop each lowering phase at the deepest range you can still control with the biceps, and do not let the weight drop the last few centimetres. If you naturally have elbows that bend slightly backwards past straight, stop a little earlier. Treat this as a firm rule for this exercise rather than a style preference.

Bench, Seat, and Implement Calibration

Adjust the preacher bench so the upper arm rests securely on the pad without the shoulder being pulled forward. The armpit should stay near the top edge without pressing aggressively into it. Test an unloaded repetition with an EZ-bar, dumbbell, cable, or machine and choose the implement that lets the wrist and elbow feel natural. A machine’s number is not comparable with an EZ-bar’s number, so record the implement and seat setting.

Grip the implement before fully extending the elbows, brace the feet, and lift without rocking the torso. Curl while keeping the upper arm supported. Lower slowly until the deepest comfortable range; do not force a locked-out bottom if the elbow loses control. A shorter repeatable range is preferable to bouncing off the pad. If the bottom is the limiter, use a lighter load, stop above the point where the elbow changes, or use a standing barbell curl regression. The incline dumbbell curl and spider curl have different shoulder and support positions.

Diagnostics, Progression, and Log

Film from the side to check whether the upper arm stays planted and from the front to compare wrists. If the shoulder rolls forward, the elbow lifts, or the torso helps, reduce load. Use three or four sets of eight to fifteen with one to three reps in reserve. Progress by repeating the same bottom range and tempo, adding repetitions, then adding the smallest load. Log date | bench/seat | implement | load | reps | bottom range | elbow stayed supported | RIR. The ACSM position stand supports gradual resistance progression but does not prescribe a universal curl grip or depth (ACSM position stand). Stop for sharp pain, numbness, weakness, or worsening symptoms.

Regressions, Range, and Practical Choices

Use a shorter range or a lighter dumbbell when the elbow cannot remain controlled near the bottom. A machine preacher curl can simplify entry and provide a repeatable seat, while an EZ-bar lets both arms share the load. A single dumbbell or cable can expose a side-to-side difference; start with the weaker side and match its repetitions. Do not treat a full lockout, a particular grip, or a deep stretch as mandatory when it changes the elbow path.

Keep the upper arm supported and the shoulder relaxed. A two-second lowering phase and a brief pause before the next curl are useful quality tests. If the wrist bends sharply, use a neutral implement or reduce the load. If the torso lifts from the seat, the load is too high. These checks describe technique and do not diagnose an elbow or shoulder condition.

Programming and Progression Record

Place preacher curls after larger pulling exercises or use them as the main biceps movement when arm isolation is the goal. Three or four sets of eight to fifteen are a practical starting range; rest sixty to ninety seconds and leave one to three clean reps in reserve. Progress when every set reaches the top of the range with the same seat, bottom position, tempo, and supported upper arm. Then add the smallest load and return to the lower end of the range.

Record date | bench/seat | implement | grip | load | reps | lowering time | bottom range | upper arm stayed planted | RIR. The log prevents a heavier machine setting from masquerading as progress on a free-weight version. The biceps exercises guide handles broader selection, while this page remains the preacher-bench execution owner. Stop for sharp pain, catching, numbness, weakness, or worsening symptoms and obtain individual advice when needed.

For a new bench, perform a light calibration set before comparing performance with an older setup. Note whether the pad is angled, where the elbow sits, and whether the implement starts from a rack or the floor. Return the weight to the rack or floor under control rather than extending beyond the range you can manage. A lighter, repeatable preacher curl is preferable to a forced bottom position or a load that makes the upper arm leave the pad.

References

See our exercise methodology for how this evidence is applied and its limits.

Preacher Curl

How to Do It

Common Mistakes