Skull crushers are similar to triceps extensions because you're in the same position and you're extending the elbows. The difference is, first, you use a barbell for this exercise which allows you to lift heavier weight. You also keep the palms facing out, instead of facing each other, which changes how you feel the movement. To stay safe, make sure you keep the barbell light or have a spotter nearby.
- Lie on the floor or a bench and hold a light-medium barbell with the hands close together, about shoulder-width apart.
- Extend the arms straight up over the chest, palms face out and thumbs wrapped around so that they're next to the fingers.
- Bend the elbows and lower the the weight down to a few inches above the forehead or until the elbows at about 90-degree angles.
- Squeeze the triceps to straight the arms without locking the joints.
- Repeat for 1-3 sets of 10-16 reps.