Dumbbell Lying Triceps Extension
The lying triceps extension is a classic mass-builder for the triceps, isolating the muscle through a long, controlled range of motion.
Equipment
Dumbbells
Difficulty
beginner
Sets & reps
3 sets · 10-12 reps
Muscles worked
Triceps
Often called a "skull crusher," this lying triceps exercise lowers dumbbells toward the head before extending the arms back up, isolating the triceps.
How to do it
- Lie on a flat bench holding a dumbbell in each hand above your chest, palms facing each other.
- Keep your upper arms still and vertical throughout the movement.
- Bend your elbows to lower the dumbbells toward the sides of your head.
- Extend your arms back up to full lockout, squeezing your triceps.
- Keep the motion controlled — this exercise is unforgiving of sloppy form near the head.
Coaching tips
- Keep your elbows pointed at the ceiling and stationary — only your forearms should move.
- Use lighter weight than you'd expect; this exercise is more about control than heavy loading.
- Lowering the dumbbells slightly behind your head (rather than straight down) can add extra stretch.
Common mistakes
- Letting the elbows flare out or drift, turning it into a different pressing movement.
- Using too much weight, which reduces control near the head and increases injury risk.
Frequently asked questions
Why is this called a 'skull crusher'?
The name comes from the bar or dumbbells lowering close to the head — a reminder to always keep the movement controlled and use a weight you can manage safely.
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