Precise form on Skullcrushers (AKA Nose Crushers or Lying EZBar Tricep Extensions) has several advantages over sloppy form. For one thing, if chosen as part of an HST program, it was likely added as a stretch point exercise. It works much better for this purpose if you keep the weight on the triceps
Secondly, proper form and shoulder placement should help prevent new injuries as well as aid healing of old ones. (See Jules' post in the close grip thread.)
To that end, as few suggestions on how to do the best skullcrusher you can do
:
1. Use a curl bar or EZ bar. A grip that rotates your thumbs up about 45 degrees will allow optimal flexion and extension of the elbow with minimal stress to the stabilizers. If all else fails, you can eliminate most of the sheering forces by switching to DBs.
2. Rotate around your elbows. Imagine there is an invisible axle running through your elbows. Try to rotate around this axle without letting the elbows flare or the shoulders move. The more your elbows move through space, the more contribution you are getting from muscles other than triceps.
3. Maintain the same strong posture and core strength you would have if there were a heavy squat bar across your shoulders. Press your feet firmly against the floor. Squeeze your glutes (balances and stabilizes pelvis). Tuck in your bellybutton (activates your deep abdominals). With the bar extended over head, try to lift that chest up and roll the shoulders down and back (as if you've just completed a beautiful seated row). Keep the shoulders firmly planted on the bench, grip that bar as if your triceps depended on it, and lower the weight slowly.
4. Try to feel the load on the triceps throughout the motion. If I balance a heavy bar overhead with my arms locked, I can hold it there for a long time without getting much work out of my muscles. In the same way, if I allow my elbows to track toward my toes, I won't have much load on the triceps by the time I get to the "top" of my extension. When you set up your "invisible axle", try to set it up so that you can still feel the load on the muscle at full extension. With my long arms (I'm from a long line of boxers
) I miss my skull completely!
Whew! I'm spent and that's all I can think of at the moment.
Happy hypertrophy!
Kate

Secondly, proper form and shoulder placement should help prevent new injuries as well as aid healing of old ones. (See Jules' post in the close grip thread.)

To that end, as few suggestions on how to do the best skullcrusher you can do

1. Use a curl bar or EZ bar. A grip that rotates your thumbs up about 45 degrees will allow optimal flexion and extension of the elbow with minimal stress to the stabilizers. If all else fails, you can eliminate most of the sheering forces by switching to DBs.
2. Rotate around your elbows. Imagine there is an invisible axle running through your elbows. Try to rotate around this axle without letting the elbows flare or the shoulders move. The more your elbows move through space, the more contribution you are getting from muscles other than triceps.
3. Maintain the same strong posture and core strength you would have if there were a heavy squat bar across your shoulders. Press your feet firmly against the floor. Squeeze your glutes (balances and stabilizes pelvis). Tuck in your bellybutton (activates your deep abdominals). With the bar extended over head, try to lift that chest up and roll the shoulders down and back (as if you've just completed a beautiful seated row). Keep the shoulders firmly planted on the bench, grip that bar as if your triceps depended on it, and lower the weight slowly.
4. Try to feel the load on the triceps throughout the motion. If I balance a heavy bar overhead with my arms locked, I can hold it there for a long time without getting much work out of my muscles. In the same way, if I allow my elbows to track toward my toes, I won't have much load on the triceps by the time I get to the "top" of my extension. When you set up your "invisible axle", try to set it up so that you can still feel the load on the muscle at full extension. With my long arms (I'm from a long line of boxers

Whew! I'm spent and that's all I can think of at the moment.
Happy hypertrophy!
Kate