Dumbbell One-Arm Triceps Extension
The dumbbell one-arm triceps extension has you hold a dumbbell overhead in one hand and lower it behind your head by bending only the elbow, then press it back up. It isolates the triceps through a long, stretched range of motion that shorter pressing exercises rarely reach, and training one arm at a time makes it easy to spot and fix strength differences between your left and right sides.
Why it works
The triceps has three heads, and the long head crosses the shoulder joint as well as the elbow, which means it only gets a full stretch when the arm is raised overhead. Bending the elbow with the arm already overhead puts the long head through that full stretched position before it has to contract to press the weight back up, a range most pressing exercises like a bench press or a standard triceps pushdown never really reach. Working one arm at a time also removes any chance of a stronger side doing more of the work without you noticing, the way it can when both arms extend a barbell together.
Set up
- Stand or sit tall holding a dumbbell in one hand, pressing it straight overhead until your arm is fully extended.
- Support your working arm at the elbow with your free hand, or let it hang naturally at your side.
- Keep your upper arm close to your head and pointed straight up before starting the first rep.
How to do it
- Bend your elbow so the dumbbell drops behind your head, keeping your upper arm still and pointed toward the ceiling.
- Lower until you feel a full stretch in the triceps, or until your forearm is roughly parallel to the floor.
- Pause briefly at the bottom of the stretch.
- Extend your elbow to press the dumbbell back up to the starting overhead position.
- Complete all reps on one side before switching to the other arm.
Form cues
- Keep your upper arm still and vertical.
- Bend only at the elbow.
- Lower until you feel a full stretch.
- Press back up without flaring the elbow out.
Breathing: Exhale as you press the dumbbell back up overhead, inhale as you lower it behind your head.
Common mistakes
Letting the upper arm drift forward or the elbow flare out to the side during the lowering phase.
Fix: Keep your upper arm pinned close to your head and pointed straight at the ceiling for the entire rep.
Using momentum from the shoulder to help press the dumbbell back up.
Fix: Slow the rep down and focus on straightening only the elbow, letting the shoulder stay completely still.
Stopping the lowering phase early and never getting a real stretch in the triceps.
Fix: Lower the dumbbell until your forearm is roughly parallel to the floor, or as far as you can control safely.
How to program it
- This isolates the triceps through a long stretch, so it responds well to moderate loads and doesn't need heavy weight to be effective.
- 2 to 3 sets of 10 to 12 reps per arm fits well as an accessory after your main pressing work for the day.
- Doing it one arm at a time roughly doubles the time needed compared to a two-arm version, so plan for that when fitting it into a session.
- Keep the weight light enough that your elbow stays pinned in place throughout; that control matters more here than the number on the dumbbell.
Safety notes
- Support the working elbow with your free hand if you feel any instability, especially with heavier loads.
- Stop the descent at a range where you can still press the weight back up with control, rather than chasing the deepest possible stretch.
Exercise profile
- Force
- Push
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How many sets of dumbbell one-arm triceps extensions should I do?
2 to 3 sets of 10 to 12 reps per arm works well as accessory work after a pressing exercise. Since you train one side at a time, budget roughly double the time of a two-arm version.
What can I use instead of the dumbbell one-arm triceps extension?
A standing dumbbell triceps extension held with both hands trains the same overhead stretch with more stability, a good option while you're still building single-arm control.
Why does my elbow hurt during this exercise?
Elbow discomfort here often comes from the upper arm drifting away from vertical, which changes the angle of stress on the joint. Keep the upper arm pinned close to your head and lighten the weight if the discomfort continues.
One-arm vs two-arm dumbbell triceps extension: which is better?
The one-arm version makes it easy to catch and correct strength differences between sides and works well once your form is solid. The two-arm version is more stable and a better starting point for beginners still learning the overhead position.