Despite its scary name, the skullcrushers won't send you to the ER, at least not if you do them correctly, But they might help you build massive triceps. It is one of the most effective and popular exercises for the triceps.
The skullcruchers is an isolation exercise that works the triceps main function - extending the elbow. It will also work your shoulders and traps as stabilizers.
You can do this exercise using EZ bar, Barbell, dumbbells and even cable.
The benefit of the skull crushers is that it works your triceps similar to the narrow grip bench press, but it gives you the full range of motion.
The drawback is that this exercise is quite risky, lose grip on the bar and you will be in severe trouble. So make sure to be very cautious doing this exercise.
Make sure to use a weight you can control, and lower the bar in a slow controller manner. This exercise isn't called skullcrusher for nothing. Using too much weight might be dangerous.
It is recommended to have a spotter. It is especially crucial if you training to muscle failure, or using very heavy weights.
Keep your upper arms perpendicular to the floor, This ensures you're working against gravity. If you're using an incline or decline bench it means your arms will not necessarily be perpendicular to your body.
Don't move your upper arms. Make sure to only extend your elbows and move the forearms, but keep the elbows in place. Moving your upper arm will take the pressure off your triceps.
At the top position, don't straighten your arms completely, keep a slight bent in your elbow. This way, the tension will stay on the triceps for the entire range of motion, not allowing them to rest.
Keep your back with a natural arch throughout the movement, tighten your abs to avoid arching your back.
If you experiencing pain during the exercise, hold your arms in a light angle towards your head, so that you lower the bar behind your head rather than the forehead. This variation usually puts less stress on the joints. Another option is to try adding a slight angle to your bench (incline or decline), to adjust your elbows to a more comfortable position.
If you feeling uncomfortable at your wrists, try using an EZ bar, its curve should allow you a more natural grip position. Another option, is to try using dumbbells.