From Bill Starr - Rotator Cuff
About your behind the neck press Mickdog
Another major cause of rotator cuff damage is behind-the-neck exercises. That's especially true for younger trainees and those who haven't yet established a solid strength foundation. The shoulder girdle simply isn't designed to move in that direction, and when you add resistance, the situation becomes more risky. Behind-the-neck presses, chins and pulldowns all place your rotator cuffs in jeopardy. I've been harping on that fact for years, but the message hasn't gotten across to many. All of those exercises are just as productive when performed to the front and not at all risky, so why tempt the gods? It's a gamble you're not going to win.
One of the problems with behind-the-neck exercises is that when you do feel the pain in your rotator cuff, it's too late. Now, if you combine sloppy form on the bench with one or more behind-the-neck movements, you're heading down the unhappy road to a rotator cuff injury'where recovery is not always swift and you could require surgery.