Muscles worked
What the skull crusher trains
Tap a muscle to see just that one and what it does in the lift.
Before the first rep
How to set up
- 01
Load a light bar. Use an EZ bar or a straight bar with the collars on. Start lighter than you think, since the bar travels over your face.
- 02
Get the bar up. Sit on the end of the bench with the bar on your thighs, lie back while holding it close to your chest, then press it up over your chest. Or have a partner hand it to you.
- 03
Lie flat. Head, upper back and glutes on the bench, feet flat on the floor. Keep your lower back in its natural position.
- 04
Grip. Overhand grip with thumbs wrapped, hands about shoulder width or a little narrower. On an EZ bar, hold the inner angled grips.
- 05
Set your arms. Straight arms with your upper arms vertical and the bar over your shoulders. Some lifters tip their upper arms slightly back toward their head instead, which is a common variant. Elbows point up at the ceiling, about shoulder width apart.
Step by step
How to do the skull crusher
- 01
Start straight. Begin with your arms locked out and the bar steady over your shoulders. Take a breath and brace.
- 02
Lower to your forehead. Bend only at the elbows and lower the bar slowly in an arc toward your forehead. Your upper arms stay still.
- 03
Stop just above. Stop when the bar is about an inch above your forehead and you feel a stretch in the back of your arms. Never let it touch your head.
- 04
Extend. Straighten your elbows to push the bar back up the same arc, keeping your elbows pointing up rather than flaring out.
- 05
Lock out. Finish with straight arms over your shoulders and squeeze the triceps for a moment before the next rep.
- 06
Finish the set. After the last rep, with arms straight, bring the bar down to your chest by bending your elbows and lowering your arms, then rest it on your thighs as you sit up, or hand it to your partner.
Cues to say in your head
- Elbows point at the ceiling
- Upper arms stay still
- Only the elbows bend
- Slow to the forehead
- Squeeze at the top
Fix these first
Common mistakes
Elbows flaring wide
Keep them about shoulder width and pointing up. If they spread out on every rep, the bar is too heavy or your grip is too wide.
Upper arms swinging
Keep your upper arms still. When they swing toward your hips on the way up, the lift turns into a pullover and close-grip press, and the triceps do less.
Dropping the bar fast
Lower over two to three seconds and stop just above your forehead. A fast drop is how bars end up hitting heads and how elbows get sore.
Cutting the range short
Lower until you feel a real stretch in the back of your arms. Small reps near lockout skip most of the work.
Bent back wrists
Keep your wrists straight and the bar over your forearm bones. An EZ bar usually makes this easier.
Thumbless grip
Wrap your thumbs around the bar every set. A thumbless grip lets the bar roll out of your hands over your face.
Stay safe
Always use a full grip with your thumbs wrapped and collars on the bar, and stop each set a rep or two before you would fail, since a missed rep happens over your face. If a rep stalls, do not try to roll the bar back over your face or let it drop behind your head: bring your elbows down toward your sides and lower the bar to your chest, keeping it clear of your face, then press it up like a close-grip bench press or set it on your thighs and sit up. For heavier sets, have a spotter stand behind your head with hands ready to take the bar. Stop if you feel sharp pain in the elbow, and get it checked if it keeps coming back.
Programming
Sets, reps and how much weight
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Muscle | 3 to 4 | 8 to 12 | 67–80% 1RM | 1 to 2 min |
| Endurance | 2 to 3 | 15 to 20 | 50–65% 1RM | 45 to 90 s |
| Technique | 2 to 3 | 10 to 12 | 50–60% 1RM | 1 min |
Plan your next session
Put in a recent set. You get working weights for your goal, a warm-up and the plates to load.
Estimated 1RM 216 lb
Endurance sets
108–140lb
2 to 3 sets of 15 to 20 reps, 45 to 90 s rest. Lighter sets for a pump or to finish an arm day. Easier on elbows that dislike heavy sets.
Estimates use the Epley formula and work best from sets of 3 to 8 reps. Treat them as a starting point and adjust by how the first working set moves.
Questions
Skull Crusher questions
What muscles do skull crushers work?
Skull crushers work the triceps, all three heads, as the only prime mover. Your lats, upper back and grip just hold your upper arms, body and the bar steady on the bench.
How do you do a dumbbell skull crusher?
Lie on a flat bench with a dumbbell in each hand, arms straight over your shoulders and palms facing each other. Bend only your elbows to lower the dumbbells beside your head toward your ears, then straighten your arms.
Should I use an EZ bar or a straight bar for skull crushers?
Either works, but most people find the EZ bar more comfortable because its angled grips keep the wrists and elbows in a more natural position. If a straight bar feels fine for your joints, use it.
Where should the bar go on a skull crusher?
Lower it toward your forehead and stop about an inch above it, never touching your head. Start with your upper arms vertical; tipping them slightly back toward your head is a common variant that tends to keep more tension on the triceps at the top.
How many sets and reps of skull crushers should I do?
For muscle growth, 3 to 4 sets of 8 to 12 reps taken within a rep or two of failure is a good default, once or twice a week. Use higher reps of 15 to 20 if heavy sets bother your elbows.
Why do skull crushers hurt my elbows?
Usually the weight is too heavy, the bar is dropping fast, or a straight bar is forcing your wrists into an awkward angle. Go lighter, lower slowly, try an EZ bar or dumbbells, and if pain keeps coming back, swap to a pushdown and have it checked.
Train in Protocol
Log your skull crusher by voice. Protocol tracks the rest.
Your last session shows up before every set, warm-ups and plates are worked out for you, and your coach sees every lift next to your sleep and recovery.