The skull crusher (lying triceps extension) is one of the most effective isolation moves for building bigger, stronger triceps. Lying on a flat bench with an EZ bar, you fix your upper arms in place and lower the weight toward your head by bending only at the elbows, then drive it back up. Because the upper arm stays angled slightly back, the triceps work through a deep stretch, which is a powerful stimulus for growth. The angled EZ bar is friendlier on your wrists and elbows than a straight barbell. It is an intermediate lift: simple to learn, but it rewards strict elbow control and punishes ego loading.
How to do the skull crusher
- Lie flat on a bench with your feet planted and grip an EZ bar on its inner angled slots, hands roughly shoulder-width, palms facing toward your feet.
- Press the bar up and position it over your upper chest or chin with arms extended, then tilt your upper arms slightly back toward your head so they sit at about 75-80 degrees rather than straight vertical.
- Keeping your upper arms fixed in that position, bend only at the elbows to lower the bar in a controlled arc toward your forehead or just behind the top of your head.
- Lower until you feel a strong stretch in the triceps, taking about two seconds on the way down without letting the bar crash.
- Pause briefly, then extend your elbows to drive the bar back to the start, squeezing the triceps hard at the top.
- Keep your elbows tucked and pointing roughly forward throughout, and stop the set when you can no longer control the lowering phase.
Muscles worked
The primary muscle is the triceps brachii, the three-headed muscle on the back of your upper arm that straightens the elbow. The skull crusher emphasizes all three heads, but because the upper arm is angled slightly overhead, it places extra stretch and tension on the long head, which originates above the shoulder and is hard to fully target with pushdowns alone. The elbow extension itself is driven by the lateral and medial heads as well. Stabilizers play a supporting role: the anterior deltoids and pecs help hold the upper arm in position, while the forearm flexors and wrist stabilizers grip and steady the bar. The core stays lightly braced to keep you anchored on the bench.
Benefits
- Builds triceps mass and elbow-extension strength, which directly carries over to bench press and overhead pressing lockout
- Loads the triceps long head under a deep stretch, a position research links to strong muscle growth
- The angled EZ bar reduces wrist and elbow strain compared with a straight barbell
- Isolates the triceps with minimal momentum, so the target muscle does the work
- Easy to progressively overload in small jumps, making it ideal for tracking arm strength over time
Common mistakes
- Flaring the elbows out wide: keep them tucked and pointing forward so tension stays on the triceps instead of the shoulders.
- Letting the upper arms drift and turning it into a pullover: lock your shoulders in place and move only at the elbow.
- Going too heavy and losing control: pick a weight you can lower slowly for a full stretch rather than dropping it toward your face.
- Cutting the range of motion short: lower to your forehead or just behind your head for a full stretch, then fully extend at the top.
- Bouncing the bar off your forehead or using momentum: control the eccentric and pause before pressing back up.
- Bending the wrists back under the load: keep them stacked and neutral so force transfers cleanly through the bar.
Form tips
- Keep your elbows still and pointed forward, hinging only at the elbow joint like a door on a hinge.
- Lower toward just behind the top of your head rather than straight down to lengthen the triceps stretch.
- Grip the EZ bar on its angled portion to keep your wrists neutral and elbows comfortable.
- Control the lowering phase for about two seconds and avoid letting the bar free-fall toward your face.
- Squeeze the triceps hard at full extension without locking out aggressively or letting the elbows drift back.
Sets & reps
For triceps hypertrophy, the skull crusher shines in the 3-4 sets of 8-12 reps range with about 75 seconds of rest, which matches the seed prescription well. Use a weight that lets you control every rep and reach a full stretch. For strength-focused work, drop to 4-6 reps with heavier load and longer rest of two to three minutes, though most lifters get the best results treating this as accessory volume rather than a max-effort lift. For muscular endurance or a finisher, run 12-15 reps with shorter rest. Because the elbows are vulnerable here, always start with a warm-up set and add weight gradually.
Frequently asked questions
Why is it called a skull crusher?
The name comes from the bar lowering toward your forehead or skull during each rep. It sounds intimidating, but with controlled form the bar travels in a safe arc and never actually touches your head. Lowering to just behind the head is a popular variation that keeps constant tension on the triceps.
Should I lower the bar to my forehead or behind my head?
Both work. Lowering to the forehead is the classic version and keeps the movement compact. Lowering to just behind the top of your head extends the stretch on the triceps long head, which many lifters find produces a better growth stimulus. Choose the path where you feel the triceps working most and can stay in control.
Why should I use an EZ bar instead of a straight barbell?
The EZ bar's angled grip lets your wrists sit in a more neutral, semi-pronated position, which reduces strain on the wrists and the inner elbow. Many lifters find a straight barbell aggravates the elbows during skull crushers, so the EZ bar is the more joint-friendly default for this lift.
How do I stop my elbows from hurting during skull crushers?
Use lighter, controlled loads, grip the angled part of the EZ bar, and avoid locking out explosively at the top. Lowering slightly behind your head rather than straight to the forehead can also ease elbow stress. If pain persists, warm up thoroughly and consider swapping in cable or dumbbell extensions.
Are skull crushers a good triceps exercise for mass?
Yes. Skull crushers are one of the best triceps mass builders because they load the muscle, especially the long head, under a deep stretch. Pairing them with a pushdown or overhead extension gives you full triceps development across all three heads and both stretched and contracted positions.