As a trade-off for mobility, the shoulder lacks some of the stability found in other joints.The shoulder is under considerable stress during many commonly performed weight training exercises and, as a result, is frequently injured. Shoulder pain is often taken for granted or ignored by many bodybuilders. For example, anterior shoulder pain felt secondary to performing bench presses (ie, achieving a "burn") is frequently assumed to be a sore anterior deltoid muscle from a hard workout. It may, in fact, represent a sign of rotator cuff strain or impingement.
thats exactly what i just did to mine still messed up

great read bro.thanks for the info