Maintain your shoulder joint rotation. Men's Health recommends this workout for maximum upper body flexibility.
Lie face down on a bench that's set at a 45º incline and hold a light dumb-bell in each hand with an overhand grip. Your arms should hang face down with your palms facing your feet. Keeping your head down, pull the weights up until your upper arms are parallel to the floor. Your elbows should point out to the side and be bent at 90º angles.
Keeping your upper arms stationary, rotate the weights forward until your palms face the floor. Pause, then reverse the movement and return to the starting position. The pulling action works the same muscles as the bent over row (the back, bicep and forearm muscles).
The shoulder rotation at the top works the muscles that can often be neglected when simply lifting weights up and down. This rotation helps maintain a healthy shoulder joint. Remember to breathe in as you pull and rotate, and breathe out as you slowly return the weights to the starting position.