Exercise Guide
How to do dumbbell one arm tricep extension
Master the setup, range of motion, and tempo for safer, more effective reps.
Overview
The Dumbbell One Arm Tricep Extension is an overhead movement that puts the triceps in a deep stretch. This is crucial because the 'long head' of the triceps (the biggest part) can only be fully stretched when your arm is over your head.
By working one arm at a time, you can use your free hand to support your working elbow, ensuring perfect form and a deep, safe stretch. It’s a fantastic way to build arm thickness and improve overhead stability.
Why Use It
- Targets the long head of the triceps more effectively than pushdowns.
- Improves overhead shoulder mobility and stability.
- Allows for a massive range of motion and a deep muscle stretch.
When to Use It
This is a great 'mid-workout' exercise. Do it after your heavy presses but before your final 'pump' moves like kickbacks.
Instructions for Proper Form
Setup
- The Seat: Sit on a bench with a short back support. Plant your feet firmly.
- The Lift: Hold a dumbbell in one hand and press it straight up toward the ceiling.
- The Support: If needed, use your opposite hand to lightly hold your working arm's bicep to keep the elbow from flaring.
Execution
- The Drop: Bend your elbow to lower the dumbbell behind your head. Keep your upper arm vertical and close to your ear.
- The Stretch: Go as low as your mobility allows—you should feel a big stretch in the back of your arm.
- The Press: Use your triceps to drive the weight back up to the starting position. Don't lock your elbow out aggressively.
Pro-Tip
Watch your ribs! It's easy to flare your ribcage and arch your back when your arm is overhead. Keep your abs tight and your ribs 'tucked' into your waistband.
Common Mistakes
- Elbow Flare: Letting your elbow point out to the side. This shifts the focus to the shoulder and can cause joint pain.
- Arching the Back: Using your lower back to help 'cheat' the weight up. Keep your core braced.
- Short Reps: Not lowering the weight far enough. The stretch is the most important part of this move!
Mistakes by Level
Beginner
- Hitting the back of the neck with the dumbbell.
- Letting the elbow drift forward.
Intermediate
- Losing core tension and arching the spine.
- Rushing the lowering phase and missing the stretch.
Advanced
- Using too much momentum from the legs (if standing).
- Failing to reach full extension at the top.
Mechanics
Use these setup and execution anchors to keep the rep organized, repeatable, and easier to progress.
Movement Pattern
Isolation
Body Position
Seated
Load Style
Unilateral
Muscles Worked
Primary
- Triceps
Secondary
None emphasized.
Stabilizers
- Core
- Shoulders
Setup Requirements
- Sit on a bench with back support, or stand tall with your feet hip-width apart.
- Press a dumbbell directly overhead with one arm.
- Keep your palm facing inward (neutral grip).
- Tighten your core so your back doesn't arch excessively.
Form Checklist
- Is my elbow pointing up, or is it flaring out to the side?
- Am I arching my lower back to get the weight up?
- Is my upper arm staying vertical?
- Am I getting a full stretch at the bottom?
Range of Motion
Lower the dumbbell behind your head by bending only at the elbow until you feel a deep stretch in your triceps, then press it back to the ceiling.
Breathing Pattern
Inhale as you lower the weight behind your head; exhale as you press it back up.
Tempo Guidance
3 seconds down to emphasize the stretch, 1 second to press up.
Caution Notes
- If you have shoulder impingement or pain when reaching overhead, try the lying version (Skull Crushers) instead.
Programming
Treat these guidelines as practical programming defaults, then scale load, volume, and frequency to match the rest of the training week.
Best For
- Building the 'back' of the arm.
- Improving overhead strength.
- Fixing arm size differences.
Goal Tags
Rep Ranges
- 10-12 reps for a balance of strength and size.
- 12-15 reps for maximum hypertrophy.
- 8-10 reps if you are focusing on overhead stability.
Set Guidance
3 sets per arm.
Rest Guidance
60 seconds between arms.
Frequency
2-3 times per week.
Pairings
- Pair with an Overhead Press to pre-fatigue the triceps.
- Pair with a Lat Pulldown to work the opposing muscles.
Audience Notes
- Beginners should do this seated to help keep the spine neutral.
- Advanced lifters can do this standing to turn it into a massive core stability challenge.
Substitution Targets
- Cable Overhead Extensions for smoother resistance.
- EZ-Bar Overhead Extensions if you want to use both arms at once.
Variations
Use progressions to increase difficulty when you master the movement, and regressions if you struggle with proper form or face mobility limitations.
Regressions
Two-Handed Overhead Extension
Using both hands on one dumbbell is much more stable.
Best for: Those with limited shoulder mobility or beginners.
Progressions
Standing One-Arm Extension
Removes the bench support, forcing the core to stabilize the entire body.
Best for: Intermediate to advanced lifters.
FAQ
Common Questions
Is seated or standing better?
Seated is better for isolating the triceps because you don't have to worry about balance. Standing is better for overall 'functional' core strength.
My shoulder feels tight. Should I do this?
If you can't get your arm straight up without arching your back, you might have tight lats. Try stretching your lats first, or stick to lying extensions.
Alternatives
Start with the closest related options, then browse fallback alternatives that keep the same primary training focus.