How to do the skull crusher

The skull crusher is a lying triceps extension: you lie on a bench and bend only at the elbows, lowering a bar toward your forehead and pressing it back up. It trains the triceps through a longer range than a pushdown, and because your arms are raised in front of you, the long head of the triceps gets more of a stretch. The trade-off is that it's harder on the elbows, so it rewards patience with the weight more than most arm exercises.

How to do a skull crusher

1. Load an EZ bar and lie back on a flat bench. Sit on the end of the bench with the bar resting on your thighs, then lie back and press it up over your chest. Plant your feet flat on the floor.
2. Take a close grip on the angled part of the bar. Your hands should be roughly 6 to 10 inches (15 to 25 cm) apart, around the width of your head. Wrap your thumbs around the bar.
3. Bring the bar over your shoulders with your arms straight. Your upper arms should point straight up at the ceiling. That upper arm angle is what you'll hold for the whole set.
4. Bend your elbows to lower the bar toward your forehead. Take two to three seconds. Stop when the bar is an inch or two above your forehead or hairline, or just behind the top of your head if your arms are angled slightly back. You should feel a strong stretch along the back of your upper arms.
5. Extend your elbows to press the bar back up. Only your forearms move. Finish with your arms straight and the bar back over your eyes or shoulders, depending on your starting angle.
6. Get out of it safely. At the end of the set, pull your elbows down toward your ribs so the bar travels to your chest, then sit up with it or hand it off. Don't try to lower it straight to the floor from over your face.

A spotter or a lighter weight is a good idea until you know where your limit is. A missed rep here ends up near your face.

Cues that help

"Upper arms are a door frame." Your upper arms stay fixed like the sides of a frame while your forearms swing like a door. It's the cue for anyone whose elbows drift toward their hips as the set gets hard.

"Elbows to the ceiling." Point your elbows up rather than out. If they flare out to the sides, try pinching your elbows toward each other slightly, as if you're holding a ball between your forearms.

"Slow down, fast up." Two or three seconds down, a normal speed up. The lowering half is where the stretch happens and where people lose control.

"Bar to your hairline." Aim for a landmark instead of "down". If that doesn't work for you, try "bar toward the top of your head", which tends to keep the upper arms from sliding forward.

Common mistakes

Elbows flaring out to the sides. It looks like the elbows splay open as the bar comes down, often with the hands creeping wider on the bar. It usually means the weight is too heavy or the grip is too wide. Bring your hands in to about head width and use a load you can lower with your elbows pointing up.

Swinging the upper arms. The upper arms rock back on the way down and forward on the way up, turning each rep into a pullover and a close-grip press. Your lats and chest start doing the work, and more weight moves than your triceps could handle alone. Set the angle at the start and hold it. Starting with your arms tilted slightly back toward your head is fine; changing that angle during the rep is the fault.

Dropping the bar too fast. Letting the bar fall to your forehead and bouncing out of the bottom puts a jolt through your elbows every rep. It's the most common reason people say skull crushers hurt. Count two or three seconds on the way down and pause for a moment with the bar just above your head.

Loading it like a compound lift. Chasing sets of 3 to 5 on an exercise where the bar travels toward your face, and where your elbows take all the strain, is asking for trouble. Keep this in the 8 to 15 rep range.

Sets, reps and how much weight to use

For muscle growth, do 3 sets of 8 to 12, with a weight you could do two or three more reps with. Skull crushers work well after your main presses, as the first or second arm exercise of the session.

Most people should never go heavier than a solid set of 8 on this lift. Heavy elbow extensions are where tendons tend to complain first, and there's not much to gain from triples on an isolation move. If your elbows start to ache, the fix is usually higher reps and a slower lowering phase.

Do a couple of light warm-up sets first, even though it's an isolation move. The empty bar for 15 reps and one set at about half your working weight for 8 is enough.

An EZ bar usually weighs somewhere between 15 and 25 lb (7 to 11 kg) depending on the gym, and that alone is a fine starting point for many people. From there, add 5 lb (2.5 kg) at a time, and only once you can do all your sets at the top of your rep range. Small plates matter here; a 10 lb jump can be a big percentage of the bar. Adding reps before weight is the easiest way to keep the numbers moving. If you log your sets in Helthy, the exercise's history shows what you did last time, which helps when the jumps are this small.

Here's roughly what people use for their working sets:

Skull Crusher working weights by bodyweight and experience

Bodyweight	beginner	intermediate	advanced
130 lb (59 kg)	15 lb (7 kg)	25 lb (11 kg)	45 lb (20 kg)
160 lb (73 kg)	15 lb (7 kg)	30 lb (14 kg)	55 lb (25 kg)
190 lb (86 kg)	20 lb (9 kg)	40 lb (18 kg)	65 lb (29 kg)
220 lb (100 kg)	20 lb (9 kg)	45 lb (20 kg)	75 lb (34 kg)
250 lb (113 kg)	25 lb (11 kg)	50 lb (23 kg)	90 lb (41 kg)

These are working weights, not maxes. Arm length makes a big difference on this one: long forearms mean a longer lever and a lighter bar, so don't read too much into where you land.

EZ bar, straight bar or dumbbells?

Use the EZ bar if your gym has one. The angled grip lets your wrists sit at a more natural angle than a straight bar, and most people's wrists and elbows notice the difference. A straight bar works, but if you feel it in your wrists, that's the reason.

Dumbbells are the other good option. Holding them with your palms facing each other takes almost all the strain off the wrists, and each arm has to do its own work. We'd pick dumbbells over any bar for anyone whose elbows already complain.

Variations and alternatives

• Dumbbell skull crusher: same movement with a neutral grip. Easier on the wrists and elbows, and handy when the EZ bar is taken.
• Incline skull crusher: done on a bench set to about 30 degrees. Your arms start further overhead, which gives the long head of the triceps a bigger stretch.
• Cable lying extension: lie on a bench with your head toward a low cable. The cable keeps tension on the triceps at the top, where a bar goes slack.
• Close-grip bench press: a heavier compound option. Grip the bar about shoulder width and keep your elbows tucked. It's the same setup as the bench press with a narrower grip.
• Tricep pushdown: the easiest swap if your elbows need a break. The cable path is gentler and you can stop anytime.
• Tricep dip: a bodyweight alternative that trains the triceps along with your chest and shoulders.

Skull crusher questions

Why do skull crushers hurt my elbows?

Usually it's too much weight, too few reps or dropping the bar into the bottom. Switch to dumbbells or a cable, keep the reps at 10 to 15 and slow the lowering down. If the pain is still there after two or three weeks of lighter work, get it looked at rather than training through it.

Should the bar go to my forehead or behind my head?

Either works. Lowering to the forehead with your upper arms vertical is the simpler default. Angling your arms slightly back and lowering the bar behind your head adds stretch to the long head of the triceps, but it's harder to control, so learn the forehead version first.

Are skull crushers better than pushdowns?

Neither is better; they train the triceps in different positions. Skull crushers put the muscle through a longer, more stretched range, and pushdowns are easier to load safely and easier on the joints. Most people do well with one of each in a week.