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Skull Crusher (Lying Triceps Extension)

Draftstrength50%intermediate⬤ limited evidence

View FHIR resourceFHIR R4 ActivityDefinition — the interoperable form of this exercise

Positions & Range of Motion

Start: supine on a flat bench, feet planted, holding an EZ-bar or dumbbells with arms extended over the chest, shoulders flexed ~90°, elbows pointed at the ceiling shoulder-width apart
End: elbows fully flexed with the load lowered under control toward the forehead/just behind the crown, upper arms unmoved, then elbows re-extended to the start over the chest
Range of Motion: isolated elbow flexion/extension through roughly 0-120°, shoulders held static at ~90° flexion with no elbow flare or drift

How to Perform

Lie supine on a flat bench holding an EZ-curl bar or dumbbells with arms extended over the chest, shoulders flexed to roughly 90 degrees. Keeping the upper arms still, bend only the elbows to lower the load under control toward the forehead or just behind the crown of the head, then extend the elbows back to the start without letting the elbows flare or drift.

Watch on YouTube↗

Opens a YouTube search for “Skull Crusher (Lying Triceps Extension)”

Equipment:EZ curl bar or dumbbellsflat bench

Starting position: supine

Coaching Cues

1
Imagine your upper arms are pillars set in concrete — only your forearms move.
(external)
2
Lower the bar toward the top of your head, then push it back up toward the ceiling, not toward your feet.
(external)
3
Keep your elbows pointing at the ceiling and shoulder-width apart; don't let them flare out.
(internal)
4
Take 2-3 seconds to lower, then extend smoothly without bouncing out of the bottom.
(tempo)

Evidence-Based Dosing & EMG Data

Recommended Dosing

For hypertrophy: 2-4 sets of 8-12 repetitions at moderate load, 2-3 sessions per week, consistent with general resistance-training guidelines; for strength emphasis, 3-5 reps at higher load once technique is stable.

EMG Activation Data

Surface EMG comparisons of common triceps exercises show the lying triceps extension produces moderate-to-high triceps brachii activation, though generally below weighted dips, close-grip pressing, or bodyweight extensions in some comparisons. Because the shoulder is held in flexion, the long head works at a longer muscle length than in pressdown variants, and recent longitudinal work on stretch-position training suggests long-length loading of the triceps (e.g., overhead or behind-the-head variants) may favor greater long-head hypertrophy. Wrist and shoulder stabilizer activity is modest and primarily isometric.

Muscles Involved (8)

Primary Movers

Triceps Brachii— All three heads drive elbow extension; the long head is loaded in a lengthened position because the shoulder is held in flexion, which is the defining feature of the skull crusher.

Stabilizers

Anterior Deltoid— Isometrically holds the shoulder at ~90 degrees flexion so the upper arm stays fixed while only the elbow moves.

Pectoralis Major— Clavicular fibers assist in stabilizing the humerus against the load; minor contribution.

Flexor Carpi Radialis— Wrist flexors co-contract with extensors to keep the wrist neutral under the bar.

Flexor Carpi Ulnaris— Contributes to wrist stabilization while gripping the bar.

Lengthened / Stretched

Brachialis— Monoarticular elbow-flexor antagonist stretched through the extension phase.

Biceps Brachii— Biarticular elbow flexor that lengthens across the elbow during the extension (lifting) phase as the antagonist.

Synergists & Assistors

AnconeusSynergist— Assists elbow extension and helps stabilize the elbow, especially near terminal extension.

Easier Variations ↓

Band or Cable Triceps Pressdown

Standing pressdown with a band or cable keeps the shoulder neutral and reduces elbow torque in the stretched position, making it easier to control for beginners or during tendon irritability.

Floor Skull Crusher with Light Dumbbells

Performing the movement on the floor limits the range of motion at the bottom (elbows can rest briefly), reducing peak stretch load and providing a built-in safety stop.

Harder Variations ↑

Incline or Behind-the-Head Skull Crusher

Increasing shoulder flexion (incline bench or lowering the bar behind the head) lengthens the triceps long head further, increasing the stretch-loaded stimulus.

Eccentric-Accentuated Skull Crusher

Use a heavier load or added band tension for a slow 4-5 second lowering phase, then assist or use both arms to return, emphasizing eccentric overload.

Target Movements (1)

Elbow ExtensionHumeroulnar Joint

Why This Exercise Matters

Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:

Pushing Up from Chairessential Pushing (Doors, Carts)

Goals This Helps With

Rehab, performance, prevention, and mobility goals this exercise supports — essential means it's a cornerstone:

Improve Overhead Pressingperformance

Research Notes

claude-researched 2026-07; muscle/movement links validated against the roster. Adversarial clinical verification pending — do not promote past needs_review without human review.