Dumbbell Skull Crusher: Technique, Muscles and Swaps
Load card
- Equipment
- Dumbbell
- Muscle group
- Triceps
- Main muscles
- triceps brachii
- Also working
- anconeus
- Mechanics
- Isolation
- Pattern
- Elbow extension
- Level
- Intermediate
The dumbbell skull crusher, also known as the dumbbell lying tricep extension, is an intermediate isolation exercise that targets the back of your arms. By using dumbbells instead of a barbell, you force each arm to work independently, which helps correct strength imbalances and allows for a more natural wrist position.
This movement focuses heavily on the triceps brachii through elbow extension. The anconeus muscle at the elbow joint also works to support the movement. Because it isolates the triceps so effectively, it is a staple for building upper body pressing strength.
How to do it
Grab a pair of dumbbells and lie flat on your back on a weight bench. Press the dumbbells straight up over your chest with your palms facing each other and your arms fully extended.
- Brace your core and keep your shoulders planted firmly against the bench.
- Bend your elbows to slowly lower the dumbbells down toward the sides of your head.
- Keep your upper arms completely still and vertical throughout the descent.
- Pause briefly when the dumbbells reach ear level or slightly below.
- Squeeze your triceps to extend your elbows and press the weights back to the starting position.
Sets, reps and load
Aim for 3 to 4 sets of 8 to 12 repetitions. Rest for 60 to 90 seconds between each set to allow your triceps to recover.
Choose a moderate weight that allows you to complete your target reps with strict form, keeping a couple of reps in reserve.
Common mistakes
- Moving the upper arms. Lock your upper arms in place so they remain perpendicular to the floor. If your shoulders move, you shift the work away from the triceps.
- Flaring the elbows. Keep your elbows tucked in and pointing forward. Letting them flare out puts unnecessary stress on the shoulder and elbow joints.
- Dropping the weight too fast. Lower the dumbbells with control to maximize tension on the triceps brachii. A slow descent also protects your joints and your head.
- Bending the wrists. Maintain a firm grip and keep your wrists perfectly straight. Letting the wrists bend backward can cause discomfort and weaken your pressing power.
Make it easier or harder
Easier
- Lying tricep extension with a single dumbbell held in both hands
- Floor dumbbell skull crusher
Harder
- Decline dumbbell skull crusher
- Pause dumbbell skull crusher
Before you load it up
- Wrist position matters here. Wrist pain is a reason to change the grip, use handles or fists, or choose another variation.
Swaps and related triceps exercises
Same muscle group with different equipment:
- Resistance Band Tricep Pushdown Resistance band
- Diamond Push-Up Bodyweight
- Parallel Bar Dip Bodyweight
- Bench Dip Bodyweight
More dumbbell options:
- Dumbbell Tricep Kickback Elbow extension
- Overhead Dumbbell Tricep Extension Elbow extension overhead
Browse all dumbbell exercises or every triceps exercise.
When to see a doctor or physio
- Sharp pain inside or around the elbow joint during the extension.
- Numbness or tingling running down your forearm and into your fingers.
- Deep shoulder pain when holding the weights in the starting position.
This page is general training information, not medical advice. If you are new to strength training, managing a health condition, pregnant or coming back from an injury, check with a doctor or physio first.
How this page was made. Exercise data (equipment, muscles, mechanics, level) compiled by the Unite Journal Crew as a general anatomy guide, cross-checked against the public-domain free-exercise-db list. Text drafted with AI assistance and edited by the crew; see our house rules. Last checked October 2026.