Exercise · Arms
Lying dumbbell triceps extension
The lying dumbbell triceps extension, also called a DB skull crusher, directly targets your triceps. You lie on a bench with two dumbbells over your shoulders and move mostly at the elbows. It’s a solid option if you want to isolate your triceps without using a machine.
Doable at all 76 gyms GoSet follows
The essentials
- Lying down, dumbbells over your shoulders, palms facing.
- Bend only at the elbows.
Muscles worked
- Primary
- Triceps
How to do it
- Set the bench to flat. Lie on your back with your feet planted on the floor, holding a dumbbell in each hand.
- Hold the dumbbells over your shoulders with your arms almost straight, palms facing each other.
- Lock your shoulders into the bench and keep your upper arms still, vertical or slightly angled back.
- Bend only at the elbows to lower the dumbbells toward your forehead or slightly behind it, taking 2–3 seconds on the way down.
- Stop just before the dumbbells touch your head, keeping your elbows tucked in.
- Press the dumbbells back up to the start position by squeezing your triceps and exhaling, without moving your upper arms.
Common mistakes
Moving the whole arm instead of the elbow
Instead : Focus on keeping your upper arms fixed. Think of your elbows as the only hinges that move, and keep your shoulders tight to the bench.
Dropping the dumbbells too fast
Instead : Control the lowering for 2–3 seconds and stop before the dumbbells touch your head. If you lose control, reduce the weight.
Elbows flaring out wide
Instead : Keep your elbows gently tucked in throughout the set. Use a weight that lets you maintain that position.
Overarching your lower back
Instead : Lightly brace your abs and keep your feet solid on the floor. If you arch too much, bring your feet closer to the bench and stabilize before each set.
Coach tips
- Inhale as you lower the dumbbells, exhale as you press back up and squeeze your triceps.
- Start with light dumbbells so you can really feel the movement at the elbows before you go heavier.
- If you’re worried about hitting your head, lower the dumbbells to a point slightly behind your forehead.
- Keep your neck neutral and look at the ceiling so your body stays stable on the bench.
Variations
- Use one dumbbell held with both hands to simplify the path of the movement.
- Set the bench to a slight incline to change the angle a bit on your triceps.
- Use one dumbbell at a time and alternate arms set to set to focus on one side.
Sets and reps
People often use this exercise after a heavier triceps movement, for about 3–4 sets of 8–12 controlled reps. Some also like it with higher rep sets at the end of a workout to finish off triceps work.
Equipment
Alternatives for the same muscles
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Common questions
How low should I bring the dumbbells?
Lower until you feel a good stretch in your triceps while staying in control and keeping your elbows steady. For most people, that’s when the dumbbells are close to the forehead or a bit behind it, without touching the head.
Can I do this triceps extension without an adjustable bench?
Yes. As long as you have a stable flat bench you can lie on, you’re good. The adjustable feature mainly helps if you want a slight incline, but flat works very well.
What if I feel pain in my elbow during this exercise?
Stop the set right away. Talk to a professional before doing it again, and in the meantime, pick another triceps exercise that doesn’t cause that pain, like a machine triceps movement or another option that feels okay.
Should I use heavy or light dumbbells?
Start with a weight that lets you keep your elbows stable and control the lowering. Then increase gradually when you can perform your reps smoothly without swinging or pain.