Skull Crusher

The skull crusher is one of the oldest dedicated triceps builders in the gym, named for the way an out-of-control bar can drop toward the lifter's face if the elbows aren't kept steady. It's a straightforward isolation move: lie on a bench, hold an EZ bar overhead, and bend only the elbows to lower the weight toward your forehead before pressing back up. Because it loads the triceps through a long, stretched range of motion, it's a staple accessory for anyone chasing bigger arms or a stronger bench-press lockout.

What muscles does the skull crusher work?

The skull crusher isolates the triceps brachii by fixing the shoulder and moving only the elbow, so all three heads share the work. Lowering the bar toward the forehead keeps the upper arms vertical and biases the medial and lateral heads, while lowering slightly behind the head lengthens the long head for a deeper stretch.

How grip and angle change muscle activation

Electromyography research shows the triceps heads share elbow-extension work unevenly depending on shoulder position. Treat these as general patterns to guide variation choice, not exact percentages.

• Bar path to the forehead: Keeps the upper arm roughly vertical, emphasizing the medial and lateral heads through a shorter, shoulder-friendly range.
• Bar path behind the head: Lengthens the long head across the shoulder joint, which research links to greater long-head hypertrophy.

Based on EMG research. [4]

How do you do the skull crusher?

To do the Skull Crusher: lie flat on a bench with your feet planted on the floor and hold an ez bar with a shoulder-width, angled grip; press the bar to straight arms directly over your chest or shoulders — this is your starting position; keeping your upper arms still and elbows pointed toward the ceiling, bend your elbows to lower the bar under control toward your forehead or slightly behind your head; stop just before the bar reaches your forehead or hairline, keeping the triceps under tension at the bottom.

1. Lie flat on a bench with your feet planted on the floor and hold an EZ bar with a shoulder-width, angled grip.
2. Press the bar to straight arms directly over your chest or shoulders — this is your starting position.
3. Keeping your upper arms still and elbows pointed toward the ceiling, bend your elbows to lower the bar under control toward your forehead or slightly behind your head.
4. Stop just before the bar reaches your forehead or hairline, keeping the triceps under tension at the bottom.
5. Reverse the motion by extending your elbows, pressing the bar back to the starting position without snapping the elbows into a hard lockout.
6. Repeat for the desired number of reps, keeping your upper arms fixed and vertical throughout the set.

What are the key skull crusher form cues?

Upper arms

Keep your upper arms perpendicular to the floor and completely still — only your forearms should move for the entire set.

Elbow direction

Point your elbows toward the ceiling, not out to the sides. Flared elbows turn the movement into a weak, joint-stressing partial press.

Bar path

Lower to your forehead or just behind your head, not to your chin or chest — a higher touch point keeps the tension on the triceps instead of the shoulders.

Wrists

Keep your wrists neutral and stacked over your forearms. Letting them cock backward under load strains the wrist joint.

Lockout

Stop just short of locking your elbows out hard at the top so the triceps stay under tension rather than resting on the joint.

Breathing & tempo: Inhale and brace slightly before you start lowering, hold that air through the stretch at the bottom, and exhale as you press back up through the sticking point. A controlled 2–3 second lowering phase with a 1–2 second press works well — the skull crusher rewards control far more than speed.

How should you warm up for the skull crusher?

Do one or two light sets of 12–15 reps with an empty EZ bar or light dumbbells to groove the elbow path and warm up the joint before loading up. A few band pull-aparts and wrist circles beforehand help prime the shoulders and forearms for the fixed overhead position.

What are the most common skull crusher mistakes?

• Flaring the elbows out to the sides — Keep your elbows pointed at the ceiling. Flaring shifts stress onto the shoulders and elbow joint and turns the exercise into a weak overhead press.
• Letting the upper arms drift backward — Fix your upper arms in place before you start. If they swing back toward your head as you lower the bar, you're using shoulder extension to cheat the range.
• Using too much weight and cutting the range short — Drop the load until you can lower the bar fully under control. A heavy, half-range rep builds less triceps and stresses the elbow more than a lighter, full-range one.
• Lowering the bar to the chin instead of the forehead — Stop the bar near your forehead or hairline — dropping it lower shortens the effective range and adds shoulder involvement.

Why does the skull crusher hurt — and how do you fix it?

Skull crusher discomfort is almost always a loading or elbow-position problem, not a reason to avoid the exercise. Match your symptom below, and see a professional if pain is sharp or persistent.

How many sets and reps should you do?

Choose your sets and reps by goal: heavier and fewer reps for strength, moderate for muscle size, lighter and higher for endurance.

RPE / RIR: Keep most skull crusher sets at RPE 7–8 (2–3 reps in reserve) since the elbow is a small, unforgiving joint that doesn't respond well to constant grinding singles. Save true failure sets for occasional high-rep pump work, not heavy loads near your face.

Place the skull crusher after your main pressing work as a triceps-focused accessory, since it isolates a muscle already pre-fatigued by compound pressing. Progress by adding a rep or two each week before the smallest available weight jump — steady increases protect the elbow better than chasing fast weight gains.

How often should you skull crusher and where does it fit?

Train the Skull Crusher 1–2 direct sessions per week, on top of the triceps work you already get from pressing, placing it after heavy compound pressing, as a triceps-focused isolation finisher.

• Frequency: 1–2 direct sessions per week, on top of the triceps work you already get from pressing
• Best split days: Push day (PPL), Arm day, Upper day
• Where to place it: After heavy compound pressing, as a triceps-focused isolation finisher

Rotate between the forehead and behind-the-head bar paths every few weeks to hit the whole triceps without accumulating the same joint stress rep after rep.

How do you progress the skull crusher?

Add a clean rep or two before adding weight, then add only the smallest plate increment once you hit the top of your rep range. Pairing skull crushers with close-grip bench press and pushdowns builds a stronger lockout.

What's the right range of motion?

Lower the bar until you feel a full stretch near your forehead or just behind your head, then press back up just short of a hard lockout. Full range of motion builds more muscle than a shortened, heavier version of the same lift.

What are the benefits of the skull crusher?

• Isolates all three heads of the triceps with a strong emphasis on the medial and long heads
• Builds the lockout strength that carries directly into a stronger bench press and overhead press
• Needs only a bench and an EZ bar or a pair of dumbbells

Who should do it: Bodybuilders chasing bigger, more complete triceps; anyone wanting a stronger bench-press lockout; and intermediate-to-advanced lifters with solid pressing technique. True beginners are better served mastering pushdowns first.

Is the skull crusher safe?

The skull crusher is safe for most lifters who use a moderate load, keep the upper arms locked in place, and stop just short of a hard lockout. Nearly all injuries trace back to too much weight or flared elbows, not the exercise itself.

Elbow tendinitis or sensitivity

Switch to cable pushdowns for a few weeks, then return with lighter loads, tucked elbows and a controlled tempo.

Shoulder impingement

Lower toward your forehead rather than behind your head, and keep the upper arms vertical instead of drifting back.

Spotting: A spotter isn't mandatory, but having one nearby for heavy sets is a smart precaution given the bar's position near your face.

How do grip and stance change the skull crusher?

• EZ-bar angled grip: The standard choice — the cambered bar keeps the wrists neutral and is noticeably kinder on the elbows than a straight bar.
• Close, narrow grip: Shifts a bit more emphasis onto the triceps at the cost of added wrist strain.
• Dumbbells (neutral grip): Lets each arm move independently and is usually the gentlest option on the shoulders and wrists.

Skull Crusher variations

How does the skull crusher compare?

Skull Crusher vs. Tricep Pushdown

The skull crusher trains the triceps through a deeper stretch at the shoulder, linked to more long-head growth. The pushdown keeps constant cable tension and is gentler on the elbows, making it a good complement rather than a replacement.

Skull Crusher alternatives

Estimate your skull crusher 1RM

Enter a weight and the reps you hit with it to estimate your one-rep max (Epley formula), then see your training percentages.

How many calories does the skull crusher burn?

Calories depend on your bodyweight and how hard you train. Resistance training has a MET value of about 3.5. Enter your bodyweight and minutes to estimate the burn (calories = MET × kg × 3.5 ÷ 200 × minutes).

Skull Crusher strength standards

Approximate skull crusher one-rep max as a multiple of bodyweight, based on aggregated lifter data. Isolation lifts like this vary more with elbow leverages, bar type, and joint tolerance than compound lifts do, so treat these as motivating benchmarks rather than a hard standard.

By age: Expect your peak numbers in your 20s–30s. Lifters in their 40s can aim for roughly 90% of these figures, 50s about 80%, and 60s+ about 65–70%, adjusting for training history and elbow health.

What counts as a good rep?

A full skull crusher rep starts and ends with straight arms directly over the shoulders or chest, with the upper arms staying vertical throughout. The bar (or dumbbells) lowers under control to the forehead or just behind the head before pressing back up — cutting the descent short or letting the elbows flare doesn't count as a clean rep.

References

1. How to Do Barbell Lying Triceps Extension: Muscles Worked & Proper Form. StrengthLog
2. Skull Crushers: Benefits, Muscles Worked, and How-To. Healthline
3. Lying Barbell Tricep Extension (Skull Crusher): Video Exercise Guide & Tips. Muscle & Strength
4. Kholinne E, et al. The different role of each head of the triceps brachii muscle in elbow extension. Acta Orthop Traumatol Turc / PMC, 2018
5. Effect of elbow joint angles on electromyographic activity versus force relationships of synergistic muscles of the triceps brachii. NIH / PMC, 2021
6. Maeo S, et al. Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position. European Journal of Sport Science / PubMed, 2023
7. Barbell Lying Triceps Extension "Skull Crusher" — exercise instructions. ExRx.net