Having your shoulders rolled forward doesn't sound like excess back muscles it actually sounds like the opposite is the problem. It sounds like the situation a novice bodybuilder is in when he works too much pec muscles and not sufficient back. When the strength of the front overpowers that of the back then the front will pull the shoulders in. Because you said your anterior and posterior delts are both strong I'd ask how your pecs(Chest) compare with your back? How about bicep to tricep? You know your body better than anyone. Assuming your muscles are in balance (back and front and to a lesser extent arms) the first thing I would try is warming up and stretching everyday. Do full body but the main stretches I would suggest are for pec, lat and shoulder: Pec: face wall, place on the wall with your hand stretched away from your body and turn your body the opposite direction. So left hand on wall, rotate body to your right. You could also try laying on your back on a bench or the floor and stick your arms out so they hang out. Lat: place one hand overhead and reach to your other side. Shoulder: standard horizontally abduct the shoulder(bring it across your body, pull it behiind your head and finally do circles. As far as exercises, I'd work on things that horizontally abduct the shoulders pull them behind you with your arms in a wingspan position. As well as rotator cuff exercises. Shoulder Abduction: take a dumbell, and bend over at 90 degrees(prop yourself up on a bench or chair) so your face is looking at the ground and the dumbell is hanging perpendicular to the ground. Have the weight in your hand with your knuckles pointing out and pull the weight out so your arm ends up parellel to the ground. http://www.cs.cmu.edu/~cline/exer/HorizontalAbduction.gif rotator cuff: get a pully, light weight or physio band, hang it at the level of your elbow when your elbow is tucked into your ribs. Then pull on it rotating your shoulder(keep the wlbow tucked in). Use both directions, so pull across your body and in toward your body. http://www.cs.cmu.edu/~cline/exer/InternalRotation.gif If the stretching fails and you feel your strength is well balanced (becaue this could definitely be it) then I'd suggest making an appointment with a physiotherapist. Skelletally the shoulder is held onto the rest of the body by the clavicle (or collar bone) which attaches from your sternum to your scapula(shoulder blade) and that to your humerus(arm). This makes me doubt that it is a structural problem but I'm not a Dr. Have you ever had a dislocation or separation? Good Luck. Edit: Mr. Wayne is correct, the rower is working your back muscles not your chest. When you pull on the handle it is causing the stuff behind you, posterior delt and back to contract. You'll also get some bicep in there.