The rotator cuff is a group of four muscles that surround the shoulder joint much like the cuff of a sock fits around your ankle. They are the body's attempt to create extra stability in an extremely flexible and somewhat unstable joint.
Unlike the hip joint, which has a large socket in which to insert the ball or head of the thigh bone, the shoulder's socket is small and shallow. This allows the shoulder HUGE ranges of motion. It also allows us to place the shoulder in improper postions, changing the way the weight is distributed through the joint.
Having proper movement of the scapulae over the rib cage helps to prevent this, so make sure your form is good on your rows. For some extra mobility in that area, you could try some "scapular push-ups". Start in top position of push-up and lightly bend the elbows. Maintaining that same bend in the elbow, try to drop the chest toward the floor by squeezing your shoulder blades together. Then press against the floor and feel those shoulder blades pulling apart as you move back to the starting position.
To work the RC directly, basically you need to get the arm bone or humerus rotating in the shoulder joint against light resistance with relatively high reps. The easiest way to do these is with cables if you have them.
Set up the cable at elbow level. Elevate your rib cage and get yourself in a strong posture. This is important. Rotating while the shoulder is not in its best biomechanical position can make things worse in stead of better.
I do ten internal rotations with elbow at waist at 30, and ten external (to the outside) roatations, elbow at waist at 20. Then I drop the cable attachment to the bottom, bring my elbow out from my shoulder, and rotate externally ten reps at 15 pounds. This is like using the shoulder horn if you've seen pics of that. Finally I do ten slow lateral raises with the cable in front of me at 10 pounds. This is considerably less weight than I would use if I were doing the laterals for my fives for example. I focus on making the motion come from the shoulder joint only and on trying to get my shoulder in a position where it does not hurt or pop. Some days go better than others
DO NOT WORK THROUGH PAIN!!! A slight ache is okay, a little soreness the day after is to be expected. Pain however is a message that something is wrong and should not be ignored.
I use these as warm up during fives, cool down if I've had any complaints. If I makes sure I do these at least once a week, my shoulders work pretty well. Every once in a while I have to quit doing them to remind myself how important they are.
If you don't have cables there are things you can do with the DBs. Hope this helps!
Kate