Muscle Group: Triceps
Skull Crushers, also referred to as Lying Triceps Extensions, work all three heads which make up the tricep muscle. Skull Crushers are a mass building tricep exercise. The name is self-explanatory – you are bringing the bar down to your skull.
Lay down on a flat bench, your knees bent, feet flat on the ground for support. Straighten your arms and hold the barbell over your head with your hands spaced about 10 inches apart.
Keep your elbows fixed and lower the barbell down till it is even with the back of your head so your triceps get a complete stretch. Push the barbell back up using a wide range of motion, lock your elbows out and squeeze your triceps for a peak contraction.
Dumbell variation: Bring the dumbbells down to the sides of your head until your triceps get a complete stretch. The dumbbells should come close to touching your shoulders. Push the dumbbells back up and squeeze.
Smith Machine variation: Bring the bar to your forehead and press up with your triceps.