Exercise guide
Dumbbell One Arm Triceps Extension On Bench
- Intermediate
- Isolation
- Rep-based
- Shoulders
- Upper arms
This unilateral isolation exercise targets the triceps, particularly the long head, by allowing for a deep stretch and focused contraction on one arm at a time. Using a bench provides a stable base, ensuring the movement remains concentrated on the triceps without excessive body sway.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Sit on the edge of a flat bench with your feet planted firmly on the floor for stability.
- Hold a dumbbell in one hand and extend that arm straight up toward the ceiling.
- Place your non-working hand on your opposite shoulder or use it to lightly support the elbow of the working arm.
- Engage your core and maintain a tall, upright posture with your head facing forward.
How to do it
- Inhale and slowly lower the dumbbell behind your head by bending only at the elbow, keeping your upper arm vertical and stationary.
- Lower the weight until your forearm is at least parallel to the floor or you feel a full stretch in the triceps.
- Exhale as you contract the triceps to extend the arm back to the starting position.
- Maintain a controlled tempo, taking approximately 2 seconds to lower the weight and 1-2 seconds to press it back up.
Form checklist
- Keep your elbow tucked in close to your head; do not let it flare out to the side.
- Ensure the upper arm remains perpendicular to the floor throughout the entire set.
- Avoid arching your lower back or poking your chin forward as the weight lowers.
- Keep your wrist neutral and firm to prevent the dumbbell from wobbling.
Pro tips
- Use your free hand to physically block the working elbow from moving forward or outward to ensure pure isolation.
- Focus on a 'mind-muscle connection' by visualizing the triceps lengthening at the bottom and shortening at the top.
- Stop just short of a full elbow lockout at the top to maintain constant tension on the muscle.
Make it harder
- Slow down the eccentric (lowering) phase to 4 seconds to increase time under tension.
- Perform the exercise from a standing position to challenge your core stability and balance.
Frequently asked
- What muscles does the dumbbell one arm triceps extension on bench work?
- The dumbbell one arm triceps extension on bench primarily targets the triceps, and also works the deltoids and forearms as secondary muscles.
- What equipment do you need for the dumbbell one arm triceps extension on bench?
- The dumbbell one arm triceps extension on bench uses dumbbell.
- Is the dumbbell one arm triceps extension on bench good for beginners?
- The dumbbell one arm triceps extension on bench is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.