Muscles worked
The triceps do the main work, with all three heads involved. Because your upper arms point up towards the ceiling rather than hanging by your sides, the long head, which also crosses the shoulder joint, works from a more stretched position than in the pushdown. Your shoulders and trunk hold your upper arms in place. Many use an EZ bar, as the angled grip tends to feel kinder on the wrists.
Common mistakes
- Elbows flaring out. As the weight gets heavy, your elbows tend to drift apart, and your chest and shoulders take over part of the work. Keep your elbows about as wide as your hands all the way.
- Rushing near your face. The bar passes close to your head on every rep. Lower it slowly and choose a weight you can safely handle for the whole set. If you go heavy, have someone spot you.
- Bent wrists. If your wrists bend back under the bar, they take part of the load. Keep them straight, in line with your forearms, and try an EZ bar if the straight grip feels uncomfortable.
Variations and alternatives
- Triceps pushdown: easier to learn and no weight near your face. Good if you are new or train alone.
- Dumbbell floor skull crusher: the same idea on the floor with dumbbells, when you train at home or have no bench.
- Overhead triceps extension: standing with a dumbbell overhead, which stretches the long head even more.
- Close grip bench press: a compound lift where your chest and shoulders help, so your triceps can handle heavier weights.
Sets and reps
When the goal is muscle, the skull crusher works best with 8 to 12 reps over 2 to 4 sets. Endurance work of 12 to 20 reps is fine with a lighter weight. Heavy sets of 3 to 5 reps are rarely worth it with a bar moving close to your face. For really heavy triceps work, the close grip bench press is a better choice. The guide to sets and reps explains how to pick a range.
With a barbell you can add weight in small steps, but even a couple of kilos can be a lot for the triceps. So add reps first, and raise the weight once you reach the top of your range on every set. Logging weight and reps shows whether you are moving forward, which is the core of progressive overload.