Single Dumbbell Dumbbell Skull Crusher
In SetGrip: Dumbbell Skull Crusher (Single Dumbbell)
- Secondary muscles
- Delts
- Body part
- Upper Arms
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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Running skull crushers one dumbbell at a time keeps the loading logic of the two-dumbbell version but adds a spotting advantage: your free hand hovers ready to assist the working arm, which makes training close to failure far less nervy with a weight over your face. Finish all reps on one side before switching.
How to do the Single Dumbbell Dumbbell Skull Crusher
- Lie flat on a bench with a dumbbell in one hand and your arm fully extended above your chest.
- Lower the dumbbell in a controlled manner towards your forehead, keeping your upper arm stationary.
- Pause briefly at the bottom of the movement, then extend your arm back to the starting position.
- Repeat for the desired number of repetitions, then switch arms.
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
Without dumbbell
Frequently asked questions
What muscles does the Single Dumbbell Dumbbell Skull Crusher work?
The Single Dumbbell Dumbbell Skull Crusher primarily works the triceps. It also involves the delts, which assist the movement and stabilise the joints.
Is the Single Dumbbell Dumbbell Skull Crusher good for beginners?
Yes. The Single Dumbbell 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 Single Dumbbell Dumbbell Skull Crusher?
If you cannot do the Single Dumbbell Dumbbell Skull Crusher, try the Banded Single Arm Side Triceps Extension, the Machine Triceps Extension or the Alternating Dumbbell Lying 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 Single Dumbbell 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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Exercise data and animations are licensed ExerciseDB content used in SetGrip. This page is for general information and is not medical or coaching advice.