Dumbbell Skull Crusher
- Secondary muscles
- Delts
- Body part
- Upper Arms
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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Two independent dumbbells separate this from the barbell skull crusher in a useful way: each arm carries its own load, so a stronger side cannot quietly take over, and the neutral grip sits easier on the wrists than a straight bar. The tradeoff is stability; total weight will be lower, and control matters more than load.
How to do the Dumbbell Skull Crusher
- Lie flat on a bench with a dumbbell in each hand, palms facing each other.
- Extend your arms straight up over your chest, keeping your elbows close to your body.
- Lower the dumbbells down towards your forehead, bending your elbows.
- Pause for a moment, then extend your arms back up to the starting position.
- Repeat for the desired number of repetitions.
Tip: Keep a slight bend at the top on lying extensions to protect the elbow, but lock out fully on cable pushdowns.
Muscles worked
Primary
Triceps · Arms
The triceps straighten the elbow, and overhead variations stretch the long head at the bottom, so you should feel the whole back of the upper arm working with a hard squeeze at lockout.
Secondary
- Delts — The front delt holds the upper arm in position on overhead extensions and should feel tension but not be lifting.
Common mistakes
- Elbows flaring out — on overhead and lying extensions the elbows should stay pointed forward or up, not out to the sides, since flaring turns it into a press.
- Upper arm moving — the upper arm should be pinned in place and only the forearm should move; if the elbow drifts, drop the weight.
- Not finishing the rep — take every rep to a full triceps squeeze; on pushdowns that means a complete lockout for a count.
- Cutting the stretch — on overhead extensions let the weight travel down behind the head until you feel the long head stretch before pressing up.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Muscle growth | 3–4 × 10–15 | 60–90 s |
| Endurance / finisher | 2–3 × 15–20 | 45 s |
| Strength | Not ideal — pick a compound lift for the same muscle | — |
Triceps extensions go after the presses in a push session or at the end of an arm day. Superset them with biceps curls on the same cable stack or with the same dumbbells.
Variations and alternatives
Similar exercises
- Incline Bench Dumbbell Overhead Triceps ExtensionDumbbell
- Dumbbell Triceps KickbackDumbbell
- Alternating Dumbbell Lying Triceps ExtensionDumbbell
- Single Dumbbell Dumbbell Skull CrusherDumbbell
- Single Arm Unsupported Dumbbell Triceps KickbackDumbbell
- Seated Single Arm Dumbbell Overhead Triceps ExtensionDumbbell
Without dumbbell
Frequently asked questions
What muscles does the Dumbbell Skull Crusher work?
The Dumbbell Skull Crusher primarily works the triceps. It also involves the delts, which assist the movement and stabilise the joints.
Is the Dumbbell Skull Crusher good for beginners?
Yes. The Dumbbell Skull Crusher is rated beginner: it uses a dumbbell and the movement is simple to learn. Start light, focus on the full range of motion and add load once every rep looks the same.
What can I do instead of the Dumbbell Skull Crusher?
If you cannot do the Dumbbell Skull Crusher, try the Barbell Skull Crusher, the Straight Bar Cable Lying Triceps Extension or the Banded Single Arm Side Triceps Extension. Each of them trains the triceps through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Dumbbell Skull Crusher, a sensible starting point is muscle growth: 3–4 × 10–15 with 60–90 s rest; endurance / finisher: 2–3 × 15–20 with 45 s rest. Do it after your compound lifts. It is a finishing movement, not the main event.
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More exercises
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- Barbell Overhead Triceps Extension
- Seated Barbell Overhead Triceps Extension
- Seated Close Grip Barbell Overhead Triceps Extension
- Behind Head Barbell Skull Crusher
- Reverse Grip Barbell Skull Crusher
Exercise data and animations are licensed ExerciseDB content used in SetGrip. This page is for general information and is not medical or coaching advice.