One-Arm Overhead Triceps Extension

Also known as: Single-Arm Overhead Triceps Extension, One-Arm Dumbbell Overhead Extension, Seated Single-Arm Dumbbell Triceps Extension

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Body Part: Triceps

Description

Sit tall with a dumbbell in one hand overhead, lower it behind your head and straighten the arm again to train your triceps one side at a time. All three heads of the triceps work. The long head crosses the shoulder, so with your arm up it starts out lengthened and the bottom of the rep is the hard part. With one arm, the forearm folds toward the other side instead of straight down, which many people find easier on the elbow than the two-hand version. It also shows quickly if one arm lags. You need one light dumbbell, and without a bench you can stand.

How to Perform

Sit near the end of a flat bench or any sturdy seat, feet flat and wider than your hips, knees at about 90 degrees.
Grip the middle of the handle, bring the dumbbell to your shoulder and press it straight up until your arm is locked out, palm forward.
Set your upper arm vertical beside your ear, elbow pointing at the ceiling. Free hand on your hip, abs braced, ribs down, no leaning back.
Bend only the elbow and lower for about 2 seconds. Your forearm folds behind your head toward the opposite shoulder; the handle turns upright.
Stop when your forearm is about horizontal and the back of your arm is fully stretched, or higher if that hurts. No bounce.
Straighten the elbow along the same arc until the dumbbell is directly over your head. Hold the lockout for a second.
Do every rep on one arm, weaker arm first, then switch. Afterward, bring the dumbbell forward to your shoulder and down to your thigh.

What Muscles Work

Primary Muscle:

Tips

Do 2–4 sets of 10–15 reps per arm, stopping one or two reps short of failure with the same reps on both sides.
Add reps first: once both arms reach 15 in all sets with a full stretch and no leaning, take the next dumbbell and go back to 10. One dumbbell step is a big jump for one arm (8 kg to 10 kg is 25%), so expect a few sessions at each weight.
At the bottom you should feel a strong pull along the back of your upper arm up toward the armpit, and a hard squeeze at lockout. Feel it in your lower back or neck? Sit taller and go lighter. Sharp elbow pain in the stretch means shorten the bottom; a pinch at the front or top of the shoulder means do a cable pushdown instead today.
Easier: hold the working upper arm in place with your free hand, or sit on a bench with an upright backrest so your back can't arch. Harder: lower over 3 seconds and pause 1–2 seconds in the stretch before you add weight.
The plates pass right behind your head and neck. Tighten the collars on an adjustable dumbbell, and always bring it down in front of you; never let it drop behind you.
Substitutes: Standing One Dumbbell French Press or Dumbbell Seated Triceps Extension to load a heavier dumbbell with both hands; One-Arm Katana Triceps Overhead Extension, the cable version that still pulls at lockout and comes in small weight steps; Cable Overhead Triceps Extension to stretch both arms at once with a rope.

Common Mistakes

Elbow drifting out to the side as the dumbbell comes down. Keep the upper arm beside your ear with the elbow pointing up; if it still wanders, go lighter or hold it with your free hand.
Upper arm swinging forward and down until the rep turns into a press. Reset it beside your head before every rep and let only the forearm move.
Cutting the rep short when the dumbbell reaches the top of your head. Lower until the forearm is about horizontal behind your head; that stretch is the reason to do this exercise.
Wrist bending back so the dumbbell hangs behind your hand. Hold the middle of the handle, wrist straight, knuckles pointing at the ceiling at lockout.