One Arm Dumbbell Preacher Curl
The one arm dumbbell preacher curl locks your upper arm against a preacher bench pad and curls a single dumbbell through a fixed path, isolating the biceps without any help from your shoulders or back. Training one arm at a time also lets you focus fully on the working side and spot strength differences between arms that a two-arm curl can hide.
Why it works
A standing curl lets you sneak in a bit of swing from the hips or shoulders, especially as the set gets hard. The preacher bench pad fixes your upper arm in place, removing that option entirely, so the biceps have to do the full job of curling the weight. Working one arm at a time on top of that removes any chance of the stronger arm covering for the weaker one without you noticing, which is common in a two-arm version once fatigue sets in.
Set up
- Sit at the preacher bench and rest one arm along the pad, with your armpit snug against the top of it.
- Hold a dumbbell in that hand with your arm extended but not locked out straight.
- Set your feet flat on the floor and keep your torso upright against the bench.
How to do it
- Curl the dumbbell up by bending your elbow, keeping your upper arm pinned to the pad throughout.
- Continue until your forearm is close to vertical, squeezing the biceps at the top.
- Pause briefly at the top of the curl.
- Lower the dumbbell back down slowly, stopping just short of fully locking the elbow out.
- Complete all reps on one arm before switching sides.
Form cues
- Keep the upper arm glued to the pad the whole rep.
- Squeeze at the top instead of just touching it and dropping.
- Lower slowly; the negative is where a lot of the work happens.
- Stop just short of locking the elbow out at the bottom.
Breathing: Exhale as you curl the dumbbell up, inhale as you lower it back down.
Common mistakes
Letting the upper arm lift off the pad near the top of the curl.
Fix: Keep light pressure through your upper arm into the pad for the entire rep, even if that means using a lighter dumbbell.
Dropping the weight quickly on the way down.
Fix: Lower the dumbbell over a slow count instead of letting gravity do the work; the controlled negative builds strength too.
Fully locking the elbow out at the bottom of every rep.
Fix: Stop just short of full extension to keep tension on the biceps and take strain off the elbow joint.
How to program it
- 3 sets of 10 to 12 reps per arm is a solid starting point for a single-joint isolation move like this.
- It fits well after your main pulling or pressing work, since it doesn't need fresh legs or a warmed-up core to perform well.
- As a light isolation exercise, training it two to three times in a week works fine as long as the arm has a day of rest somewhere between sessions.
Safety notes
- Avoid locking the elbow out hard at the bottom of the rep, which can strain the joint over repeated sets.
- Choose a dumbbell light enough that your upper arm stays pinned to the pad for every rep, not just the first few.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How many reps of one arm dumbbell preacher curl should I do?
10 to 12 reps per arm for 3 sets is a good range for building both strength and control in the biceps.
One arm vs two arm preacher curl: which is better?
The one-arm version stops the stronger arm from taking over unnoticed as you fatigue, which makes it useful for fixing a size or strength difference between arms. The two-arm version lets you use more total weight and takes less time to finish a set.
Why do I feel this more in my shoulder than my biceps?
Your upper arm is probably lifting off the pad during the curl. Keep light pressure into the pad through the whole rep and lighten the weight if that's what it takes.
Can I do preacher curls without a preacher bench?
A regular incline bench angled so your arm rests along it can work in a pinch, though a proper preacher pad gives a more consistent, locked-in position.