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Skull Crusher

The skull crusher — lying triceps extension — lowers dumbbells from arms-vertical toward the forehead by bending only the elbows, then extends back up. Performed lying on a bench or the floor, it isolates the triceps under a stretch few pressing movements reach, making it a core mass-builder for the back of the arm. Coached by Maddy (NASM-CPT) — these are the exact form cues he gives on every client's first week.

Muscles worked

Triceps · triceps brachii Anconeus

Sets & reps by goal

Goal	Sets × Reps	Rest
Strength	4 × 4–6	2–3 min
Muscle	3–4 × 9–12	60–90 s
Endurance	3 × 15–20	45–60 s

Rep ranges per Helms 2014 · Schoenfeld 2016.

Level — Beginner

Beginner-appropriate with light dumbbells — respect for the lowering phase is the only prerequisite.

Proper form — 5 cues

Lie down and press the dumbbells to arms vertical over the chest
Angle the upper arms slightly back toward your head and keep them frozen
Bend only the elbows, lowering the weights beside your temples
Stop just short of touching, then extend back to straight
Keep wrists neutral, palms facing each other throughout

Breathing: Inhale lowering toward the temples, exhale extending to straight.

The 3 mistakes Maddy corrects most

Upper arms drifting toward the hips during the lift. The drift converts the extension into a narrow press, letting the chest and shoulders rescue the triceps. Fix: Fix the upper arms at their slight backward angle and let the forearms do every bit of the moving.

Flaring the elbows wide. Wide elbows dump the tension out of the triceps' line and stress the elbow joint at the turn-around. Fix: Keep the elbows tracking straight up, roughly shoulder-width, visible in your peripheral vision.

Going too heavy over your own face. This exercise's name is a warning — control lost near the temples has consequences other lifts do not. Fix: Use dumbbells you can lower on a three-count with total confidence, and leave a rep in reserve on every set.

Common questions

Why are they called skull crushers?

Because the lowering path aims the weight at your head — the name is gym humor doubling as a safety briefing. Done with control and sensible loads, the exercise is no more dangerous than any other free-weight movement; the name simply reminds you that the lowering phase deserves full attention.

Skull crushers vs triceps pushdowns — which builds bigger arms?

Skull crushers load the triceps in a stretched position, which is a powerful growth signal, while pushdowns emphasize the squeeze near lockout with smoother joint stress. They complement rather than compete — a triceps program with one lying extension and one pushdown-style movement covers both ends of the range.

My elbows hurt during skull crushers — what should I change?

Three adjustments solve most cases: lighten the load and slow the descent, lower the dumbbells behind the head rather than to the forehead — which reduces the sharpest elbow angle under load — and warm up with pushdowns first. If pain persists across sessions, swap the movement and get the elbow assessed.

Related exercises

Easier: Skull Crusher (Modified)

Overhead Triceps ExtensionTriceps Triceps ExtensionTriceps Triceps Extension (Modified)Triceps Triceps Kick BackTriceps Upward Triceps ExtensionTriceps

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