The rotator cuff is an extremly complex joint, i have been bodybuilding for over 20 years and suffered a shoulder impingement about 4-5 years ago, it came on very slowly to the point i had to stop completely.
I had a cortisone shot which cured the sharp pain i was getting but the problem is still there, but does not bother me unless i train out of a certain area, ie flyes, pec dec etc. i. I started wc 18 months ago and its ok but i think we all need more dietry fat in our diets especially from red meat and also eat a couple whole eggs a day and just generally eat a good healthy diet. The fats for lubricating the joints.
I'm sorry but red meat eggs and loads of fat, isn't a healthy diet and certainly wont protect your joints. One of my customers recommended Chrondoitin and glucosamine tablets for joint problems. He swore by them. I was sceptical but after taking them for a month all my aches and pains disappeared. I've been on them ever since (4 years) because they continue to protect and rejuvinate. I buy them in bulk from Holland and Barret when they are in their half price sale.