Skull Crusher: Muscles Worked and How to Do It
TL;DR
The skull crusher is a triceps-focused isolation exercise: your triceps extend the elbow to lift the EZ bar back overhead, while your forearms grip the bar and keep your wrists steady through the movement. Because the elbows stay fixed, almost all the work falls on the triceps.
- Primary muscle:
- Triceps
- Secondary muscles:
- Forearms
Muscles worked
Your triceps are the prime mover. Bending the elbows to lower the bar toward your forehead stretches the triceps, and extending them back to lockout is what builds strength and size in the muscle. Because the upper arms stay still, the triceps get very little help from other muscles.
Your forearms grip the EZ bar and keep the wrists from bending backward under the load. A firm grip through the set also helps you control the bar's path as it lowers toward your head.
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How to do it
- Using a close grip, lift the EZ bar and hold it with your elbows in as you lie on the bench. Your arms should be perpendicular to the floor. This will be your starting position.
- Keeping the upper arms stationary, lower the bar by allowing the elbows to flex. Inhale as you perform this portion of the movement. Pause once the bar is directly above the forehead.
- Lift the bar back to the starting position by extending the elbow and exhaling.
- Repeat.
Form tips
- Keep your upper arms pointed straight up and still. Only the forearms should move.
- Lower the bar toward your forehead under control, not past the point where your elbows flare out.
- Use an EZ bar if a straight bar bothers your wrists. The angled grip is easier on the joint.
- Have a spotter nearby when you're loading heavier weight, since the bar travels close to your head.
Exercise details
| Equipment | EZ curl bar |
|---|---|
| Level | Beginner |
| Mechanic | Isolation |
Used by lifters following PPL, 5x5, upper/lower, and more.
Frequently Asked Questions
Why are they called skull crushers?
The name comes from the bar's path: it lowers close to your forehead before you press it back up. Done with control, the bar never gets near your head, and the exercise is simply a triceps isolation move.
How many reps should I do for skull crushers?
For muscle size, 6-12 controlled reps per set with a moderate weight is a common range. Keep the load lighter than you'd use on a compound press, since the triceps are working alone here.
What's a good compound exercise to pair with skull crushers?
A dumbbell floor press trains the triceps through a heavier compound movement, so pairing the two covers both isolation and compound triceps work in one session.
More triceps exercises
Exercise instructions and photos come from the free-exercise-db library, public domain, the same library used inside the PR Streak app.
