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Exercises / Isolation Intermediate

Exercise demo

Dumbbell skull crusher

The dumbbell skull crusher overloads the long head of the triceps in a way that pushdowns simply cannot. It is also kinder on the elbows than the barbell version, which is why most lifters past 40 should default to it.

Primary muscle

Triceps

Equipment

Dumbbell

Force

Push

Mechanics

Isolation

Setup

Lie on a flat bench with a dumbbell in each hand. Press them up to lockout above the chest, palms facing each other. The upper arms should be vertical and the elbows pointing toward the ceiling. That is your start position for every rep.

How to do it

  1. 1

    Lock the upper arm

    Pin the upper arms in place. Only the forearm moves. Picture trying to point the elbows at the ceiling the whole set.

  2. 2

    Lower toward the head

    Bend the elbows and bring the dumbbells down toward the forehead or just past it. Take a slow three-count down. The hands end roughly level with the ears.

  3. 3

    Pause at the stretch

    Hold the bottom position for a half second. This is the working range that builds the long head of the triceps.

  4. 4

    Extend back to lockout

    Press the dumbbells back up by straightening the elbows. Lock the arms out without flaring at the top, then go straight into the next rep.

Common mistakes

  • • Letting the elbows flare outward during the lowering, which turns the lift into a triceps press and removes the stretch.
  • • Dropping the dumbbells fast, which loads the elbow joint at the bottom.
  • • Lockouts that fully hyperextend the elbow at the top.
  • • Going too heavy before the upper arms can stay still through the rep.

Variations

Incline skull crusher

Bench at 15 to 30 degrees, dumbbells come down past the head. Stretches the long head harder. Save it for once the flat version feels easy.

Cable overhead extension

Same target, no elbow load at the bottom. A good substitute on heavy bench days.

Close-grip bench press

Compound triceps work. Stack it before the skull crusher in a workout for a heavier and a stretched stimulus.

FAQ

Why dumbbells over the EZ bar? +
Two reasons. First, the wrists can rotate freely so the elbows hurt less. Second, each arm has to work independently, which surfaces the side-to-side imbalances most lifters develop after decades of bench pressing.
How much weight? +
Start lighter than you think. The long head is most active in the stretched position, where it is also weakest. Three sets of 10 to 12 with strict form will grow the triceps faster than heavier sets where the elbows ache for two days.
My elbows hurt during this lift. What do I do? +
Narrow the grip, slow the lowering, and lower only as far as the elbows are happy. If pain persists, swap to cable overhead extensions for four weeks. The stretch is what builds the muscle; the bottom range is non-negotiable.

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