Before we get into that, let me get something off my chest... I used to be petrified of chin-ups and pull-ups. I always knew they were a great compound exercise, but I was so focused on the fact that they trained the lats (an internal rotator of the gleno-humeral joint), that I never thought about the big picture.
In reality, a well performed chin-up or pull-up, where you actively depress the scapulae at the top, may be one of the best shoulder stability exercises you can perform.
Unfortunately, this leads us to another issue. Performing a chin-up or pull-up with full scapular depression at the top is damn hard! So how do we get there? As much as I hate to admit it, it's time to get reacquainted with the lat pulldown machine.
http://www.t-nation.com/free_online...ning_performance/top_priority_for_lower_traps