Barbell Lying Triceps Extension exercise animation (Male)

Barbell Lying Triceps Extension

Target muscle
Triceps Brachii
Equipment
Barbell
Body part
Upper Arms
Type
Strength

The barbell lying triceps extension, commonly called the skull crusher, is an isolation exercise that targets the triceps brachii. Performed lying on a flat bench, it lets you load the triceps directly through a full stretch and contraction, making it a staple for building arm size and lockout strength.

How to do the Barbell Lying Triceps Extension

  1. 1Lie flat on a bench with your feet planted firmly on the floor and your head near the end of the bench.
  2. 2Grip a barbell with an overhand, shoulder-width grip and press it up so your arms are fully extended, the bar held directly over your chest or shoulders.
  3. 3Keeping your upper arms fixed and pointing toward the ceiling, bend at the elbows to lower the bar under control toward your forehead or just behind your head.
  4. 4Lower until you feel a stretch in your triceps, keeping your elbows from flaring out to the sides.
  5. 5Extend your elbows to drive the bar back up along the same path until your arms are fully straight.
  6. 6Pause briefly at the top with the triceps fully contracted, then begin the next rep.
  7. 7Complete your reps, then carefully lower the bar to your chest and sit up, or hand it to a spotter, before setting it down.

Form tips

  • Keep your upper arms still and vertical throughout the set so the movement happens only at the elbow and the tension stays on the triceps.
  • Use a controlled tempo on the way down rather than dropping the bar, since the bar travels close to your face.
  • Lower the bar toward your forehead or just behind your head — slightly behind keeps more constant tension on the triceps and reduces elbow strain.
  • Use a spotter or start with a light, manageable load whenever you train this lift, because the bar passes directly over your face.

Common mistakes

  • Letting the elbows flare out and drift wide, which turns the movement into a press and takes work off the triceps.
  • Letting the upper arms swing back and forth, which uses momentum and the shoulders to cheat the rep and cuts triceps tension.
  • Lowering too fast or losing control near the face, which is dangerous given the bar's path over your head.
  • Going too heavy and shortening the range of motion, which limits the triceps stretch and the muscle-building benefit.

Frequently asked questions

What muscles does the barbell lying triceps extension work?

It isolates the triceps brachii, the muscle on the back of the upper arm. Because the upper arms stay fixed, the triceps do nearly all the work to extend the elbows.

Is the barbell lying triceps extension the same as a skull crusher?

Yes. "Skull crusher" is the common gym name for the lying barbell triceps extension, referring to lowering the bar toward your forehead before extending back up.

Should I lower the bar to my forehead or behind my head?

Both are valid. Lowering to the forehead is the classic version, while lowering just behind your head keeps more constant tension on the triceps and can be easier on the elbows.

How many sets and reps should I do?

As an isolation move, it responds well to moderate loads. Three to four sets of 8–12 reps is a sensible default for building triceps size and strength.

Is this exercise safe to do without a spotter?

It can be, but the bar travels over your face, so control matters. Start light, keep the descent controlled, and use a spotter whenever you train near your limit.

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