Skull Crushers: Proper Technique, Common Mistakes, and Who They Suit

The skull crusher is one of the few exercises that loads the triceps while it's stretched — the upper arm sits overhead or close to it, and the long head works at full length. That's why it works, and also why technique falls apart faster here than almost anywhere else once the weight gets ambitious. Below is the setup step by step, the mistakes you'll see in every gym, and an honest read on who should be doing it.

What the exercise actually does

The triceps has three heads. The lateral and medial heads only extend the elbow, but the long head crosses the shoulder joint too, so it only reaches full stretch when the upper arm goes overhead or behind the line of the torso. Bench pressing and dips give the triceps plenty of work, but they keep the long head short. The skull crusher fills that gap.

Practical consequence: if you already do 12–16 pressing sets a week (flat bench, incline, overhead press), the skull crusher isn't "one more press" — it's a different stimulus. That's why it belongs in lower volume and higher reps: 8 to 15, not 3 to 5.

Setup and execution, step by step

1. Lie on a flat bench, feet planted, shoulder blades pulled together, lower back in its natural curve. If your back complains, put your feet up on the bench or use an incline of 15–30 degrees.
2. Take an EZ bar at shoulder width or slightly narrower, hands on the angled section. A straight bar works, but for most people it bends the wrists into an uncomfortable position.
3. Press the bar up, then tilt your arms 20–30 degrees toward your head. That's the starting position. If your arms are vertical, the triceps gets a rest at the top and half the point of the lift disappears.
4. Bend the elbows and lower the bar over 2–3 seconds, toward the crown of your head or past it. The upper arm stays put; only the forearm moves.
5. Lower until you feel a full triceps stretch — for most people that's when the bar is level with the top of the head or 5–10 cm behind it. No tapping your skull, no bouncing out of the bottom.
6. Extend the elbows under control, roughly 1 second, and stop before the arms reach vertical. Half a second pause at the top, then down again.

Breathe in before you lower, out as you finish the extension. Picture someone holding your upper arms in place and not letting them move — that's the whole lift in one image.

Variations and when to pick each

EZ bar on a flat bench

The standard. Easiest to track because you can add 1.25 kg per side. Good choice if your elbows are healthy.

Dumbbells, neutral grip

Palms facing each other. The kindest version for elbows and wrists, and each arm works on its own so strength differences show up. Start with 6–10 kg dumbbells.

Overhead extension (seated, bar or cable rope)

The biggest long-head stretch, since the upper arm is fully vertical. Needs decent shoulder mobility; if your ribs flare forward, drop the weight.

Cable version lying on a bench

Tension stays constant through the top of the range. The best option for sets of 12–15 when you want work without loading the joints hard.

Common mistakes

• Too much weight. If the last 2 reps look like a close-grip bench press, the bar is too heavy. Take 20 percent off and rebuild the tempo.
• Elbows flaring out. The distance between your elbows should be identical on rep one and rep twelve.
• Upper arms drifting backward. Do that and it becomes a pullover driven by lats and chest, with the triceps doing less.
• Vertical arms at the start. The classic error — no resistance at the top means part of every set is a break.
• Cutting the range short. Stopping halfway down your forehead isn't a stretch. Go to the crown or past it.
• Bouncing out of the bottom. The fastest route to an irritated triceps tendon at the elbow.
• Too heavy, too often. Three hard skull crusher sessions a week is something nobody sustains past a month.

The concrete numbers

• Sets: 2–4 working sets per session.
• Reps: 8–15. Below 8 the risk climbs; above 15 technique usually degrades from fatigue.
• Rest: 60–90 seconds.
• Frequency: 1–2 times per week; total weekly triceps volume of 6–12 sets including everything else.
• Progression: when you hit the top of the rep range in every set for two sessions in a row, add 1.25–2.5 kg total.
• Warm-up: 1–2 light sets of 12–15 reps at 40–50 percent of your working weight.

Who it suits, and who should skip it

It suits you if you've been training for at least 3–4 months, your elbows don't ache during everyday movements, and your triceps lags behind your chest and shoulders. It's especially useful for people who do plenty of push-ups and dips but never take the long head into a stretch.

Skip it if you have active elbow pain, if you're a complete beginner in your first 6–8 weeks (learn pressing and push-ups first), or if you're coming back from a shoulder injury and can't hold your arm overhead comfortably. A substitute that delivers roughly 80 percent of the benefit with less risk: cable rope or bar pushdowns, 3 sets of 12–15.

When to see a doctor

See a doctor or physiotherapist if elbow pain lasts more than 10–14 days and doesn't settle with rest, if it shows up during ordinary tasks like opening a door or carrying a bag, if you hear a pop followed by sudden loss of strength, or if the joint swells and feels red and warm. Tingling or numbness in the fingers after sets is also worth checking, because that's usually a nerve rather than a muscle.

Pain that shows up mid-set and fades in a couple of minutes is one thing. Pain that's waiting for you in the morning for the third day running is something else.

The short version

• Tilt your arms 20–30 degrees toward your head and keep the upper arms frozen — that's the difference between triceps work and flailing.
• Lower for 2–3 seconds to the crown of your head or past it, with no bounce at the bottom.
• 2–4 sets of 8–15 reps, 60–90 seconds rest, 1–2 times per week.
• Add 1.25–2.5 kg only after you hit the top of the rep range in every set for two sessions running.
• Elbow pain past two weeks, swelling, or tingling fingers — that's a doctor's appointment, not another session.