Legion,
You might want to try a couple of different things with the skull crushers or lying tricep extensions. First of all, are you keeping your elbows close together? Are you allowing the bar to travel to your forehead? If so, this could be part of the problem. For one, this is not a natural movement. Elbows close together and letting the bar travel to the forehead is creating a motion that your body does not want to perform. Here might be a couple of things you can try:
Lying Tricep Extensions with bar:
1. Widen your grip to about 18 inches
2. let the bar travel to the back of the head
3. the back of the arms should remain stationary at about 45 to 60 degrees.
4. All of the stress will be placed on the long tricep head.
This sounds a little vague, but it is hard to describe without showing. This exercise can be performed without damaging your elbows. The key is to find out the movement that works for you. If you are not comfortable with performing this exercise at all, here are a couple of alternatives:
1. Parallel Dips
2. Overhead Dumbbell Extensions (use a triangle grip using both hands
3. Bench Dips (make sure arms are parallel to floor at the bottom of the motion)
4. Pulley Press Downs (use moderate weights 8 to 10 reps)
I hope some of this information helps. Good luck!
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