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
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
How to program skull crusher
| Goal | Sets | Reps | Tempo | Rest | RPE |
|---|---|---|---|---|---|
| Strength — entry | 3 | 4-5 | 2-1-1-0 | 2 min | 7 |
| Strength — standard | 4 | 4-6 | 2-1-1-0 | 2-3 min | 8 |
| Strength — advanced | 4 | 6, 1 s pause in the stretch | 2-1-1-0 | 2-3 min | 8-9 |
| Hypertrophy — entry | 3 | 8-10 | 3-0-1-0 | 60-90 s | 7 |
| Hypertrophy — standard | 3-4 | 9-12 | 3-0-1-0 | 60-90 s | 8 |
| Hypertrophy — advanced | 3-4 | 12, lowering behind the head for a longer stretch | 3-1-1-0 | 90 s | 8-9 |
| Endurance — entry | 3 | 12-15 | 2-0-1-0 | 45-60 s | 6-7 |
| Endurance — standard | 3 | 15-20 | 2-0-1-0 | 45-60 s | 7-8 |
| Endurance — advanced | 3 | 20, constant tension, no lockout rest | 2-0-1-0 | 45 s | 8 |
| Beginner on-ramp — week 1-2 | 2 | 8-10, lightest dumbbells | 3-0-2-0 | 90 s | 5-6 |
| Beginner on-ramp — week 3-4 | 3 | 8-10 | 3-0-1-0 | 60-90 s | 6 |
| Deload / elbow-friendly | 2 | 8, half load, reduced range | 3-1-3-0 | 90 s | 5 |
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)
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