Dumbbell Lying One Arm Supinated Triceps Extension exercise animation (Male)

Dumbbell Lying One Arm Supinated Triceps Extension

Target muscle
Triceps Brachii
Equipment
Dumbbell
Body part
Upper Arms
Type
Strength

The dumbbell lying one arm supinated triceps extension is a single-arm isolation exercise that targets the triceps brachii. Performed lying on a bench with an underhand (supinated) grip, it lets you work one arm at a time to even out side-to-side strength while keeping constant tension on the triceps.

How to do the Dumbbell Lying One Arm Supinated Triceps Extension

  1. 1Lie flat on a bench holding a dumbbell in one hand with a supinated (underhand, palm facing toward your head) grip.
  2. 2Press the dumbbell up until your arm is fully extended directly over your shoulder.
  3. 3Keep your upper arm vertical and fixed in place; this is your starting position.
  4. 4Bend at the elbow to lower the dumbbell under control toward the same-side shoulder, keeping your elbow pointed at the ceiling.
  5. 5Lower until you feel a stretch in the triceps, keeping your upper arm still throughout the rep.
  6. 6Press the dumbbell back up by extending the elbow until your arm is fully straight again, squeezing the triceps at the top.
  7. 7Complete all reps on one arm, then switch the dumbbell to the other hand and repeat.

Form tips

  • Move only at the elbow — keep your upper arm locked vertical so the triceps does the work instead of the shoulder.
  • Use a controlled tempo and avoid letting the dumbbell drop; the lowering phase is where the triceps stretches under load.
  • Brace your free hand near your working elbow to steady the upper arm and stop it from drifting.
  • Start lighter than you would for a two-arm movement, since the supinated grip and single-arm setup are less stable.
  • Keep your wrist firm and neutral so the load stays over your forearm rather than bending the wrist back.

Common mistakes

  • Letting the elbow drift forward or flare out, which turns the movement into a press and takes tension off the triceps.
  • Using momentum or swinging the dumbbell, which reduces muscle work and risks straining the elbow.
  • Lowering only halfway, which shortens the range of motion and limits the triceps stretch and growth.
  • Going too heavy and losing control, which can strain the elbow joint or drop the dumbbell toward your face.
  • Training one arm noticeably harder than the other, defeating the purpose of single-arm work.

Frequently asked questions

What muscles does the dumbbell lying one arm supinated triceps extension work?

It isolates the triceps brachii — the muscle on the back of the upper arm responsible for straightening the elbow. Working one arm at a time helps correct strength imbalances between sides.

Why use a supinated (underhand) grip?

The underhand grip changes the angle of pull on the triceps and can feel more comfortable on the wrist and elbow for some lifters. It keeps tension focused on the triceps through the extension.

How many sets and reps should I do?

As an isolation exercise, 2–4 sets of 10–15 reps per arm with a controlled weight works well. Prioritize form and a full stretch over loading heavy.

Is this exercise good for beginners?

Yes, as long as you start light. The single-arm, supinated setup is less stable, so use a manageable dumbbell and keep your upper arm fixed before adding weight.

Where should I feel this exercise?

You should feel it in the triceps on the back of your working upper arm, especially as you extend the elbow. If you feel it mostly in the shoulder, your upper arm is moving instead of staying fixed.

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