Been my view for a long time that most guy's do not have the shoulder girdle flexible (stiffness and limited range of motion) for the PBN (as opposed to BNP), to do it injury free. The PBN can be a very safe and rewarding exercise, and even strengthen the shoulder girdle greatly, if some measures are taken into consideration.
Warm up the area by just using a light stretching exercise bar and doing the exercise. Straight arm pullovers, or just hanging loosely from a overhead bar, can be included in the warm-ups/stretches. Holding the BB too wide (try a 90 degree angle between the arms/forearms at the bottom position)). Lowering the bar down too far (try touching the mid to upper trap area, no lower) need to be avoided. Probably the major cause of injury would be to rush the weight, using too much weigh on the bar, too soon before the shoulders are ready for it.
Upright rows are also blamed for injuries, but if the bar in kept near the body during the lift and a narrower grip, a lot of an negative affect is reduced. Trouble being that most guy's lift the BB out and away from the body, placing too much stress on the shoulder joints. And, most of the time, the grip is too wide.
I, and others, have SS'ed the PBN with upright rows (moderate style push-pull) with good results. Also pre-exhausted the delt area with laterial raises first, followed (no rest at all) with the PBN. Works well with the upright rows also. One of the better delt builders is the one arm DB side press exercise for thick and full development. Most back (pulling movements) exercise should take care of the posterior delts. If not, than try bentover DB rows with the elbows out wide and away from the body. Can pre-exhaust here also by doing a set of rear DB flys or pec deck reverse flys, before doing the bent over wide arc DB rows. Good Luck.
