Exercise guide · evidence-graded

Skull Crushers

The barbell skullcrusher, or lying triceps extension, is an arm isolation exercise: lying on a flat bench, you bend your elbows to bring a barbell down towards the top of your head, then straighten them to press it back up. It works all three heads of the triceps and is one of the most loadable triceps isolation exercises.

Also called: Lying Tricep Extension, French Press, Nose Breakers, Skullcrusher · Equipment: barbell · Pattern: isolation

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How to do it

Step by step

Lie on your back on a flat bench with your feet flat on the floor and your head supported at the end of the bench.
Take an overhand grip on the bar with your hands about shoulder-width apart or slightly narrower, thumbs wrapped around it.
Hold the bar at arm's length over your shoulders, not over your chest.
Tilt your upper arms slightly back towards your head so your elbows point a little behind vertical. Keep them in this position for the whole set.
Bending only at the elbows, bring the bar down under control towards your hairline or just behind the top of your head.
Straighten your elbows to press the bar back up to the start position, moving only your forearms.
Keep your ribcage down and your back in contact with the bench for every rep.
After the last rep, bring the bar down to your chest with bent elbows before sitting up, or hand it to a spotter.

Coaching cues

Upper arms still, only your forearms move
Elbows tilted slightly back towards your head
Bring the bar to your hairline, not your chest
Control the bar down into the stretch
Elbows pointing up, about shoulder-width apart

In VALDA, these cues are one tap away on the exercise while you train.

Muscles worked

What it trains

Muscle	Role	Evidence
Triceps brachii: long head	Prime mover	C
Triceps brachii: lateral head	Prime mover	C
Triceps brachii: medial head	Secondary	C
Anconeus	Secondary	D
Forearm flexors	Stabiliser	D

Evidence grades: A = strong research base · B = good · C = limited · D = coaching consensus.

Common faults

What goes wrong, and the fix

Upper arms swinging on the way up

Fix: Hold your upper arms still and move only at the elbows.

Bar drifting towards the chest

Fix: Bring the bar down towards your hairline or just behind your head.

Dropping the bar fast towards the face

Fix: Take two to three seconds to bring the bar down to your hairline.

Elbows flaring out wide

Fix: Keep your elbows pointing up and about shoulder-width apart.

Arching the back to finish reps

Fix: Keep your ribs down and your back on the bench, with a load you can control.

Programming

What the research says

Muscle growth · first choiceStrengthGeneral fitnessEndurance

Muscle length — A controlled trial found triceps extensions done with the arms overhead grew the triceps about 1.5 times more than with the arms by the sides. The skullcrusher's angled-back arms sit between the two positions.
Load and reps — Research comparing loads finds muscle growth is similar across a wide range of loads when sets are taken close to failure. Many lifters use about 6–10 reps for strength-focused work and 8–15 for size.
Effort — Studies show sets that finish a few reps short of failure capture most of the growth benefit; true failure adds only a small extra effect.
Volume — Research links more weekly sets for a muscle to more growth, with diminishing returns. Pressing also works the triceps, and counting those sets improves volume estimates.
Tempo — Research finds similar growth across rep durations of about half a second to 8 seconds. A controlled descent into the stretch is common practice.

Alternatives · VALDA FLEX

Swap it mid-workout

With VALDA Pro, FLEX offers alternatives like these when you swap an exercise mid-workout.

Log the skull crushers in VALDA, with these cues one tap away while you train and your history for it in one place.

General information about exercise technique, not medical advice. If you have an injury or a health condition, your healthcare provider is the right person to ask.