A word about deltoids: When people refer to exercising their "shoulders", what they usually mean are their deltoids. (The shoulder joint is acted on by the deltoids plus the pectorals, back muscles, arm muscles, etc.)
I like to think of the three components of the deltoid (front, medial and rear) as three separate muscle groups and to work them thus. Start with exercises for the rear deltoid and move forward to the medial and finally the front deltoid. Be careful not to overtrain the front deltoid, which sustains significant loads during chest workouts.
Rear Delts: Seated Cable Rope Pull
I developed this exercise as an update to a standing cable rope pull. My clients all love this exercise because it makes it easy to isolate the rear deltoid. "You really know what you're working."
Set an incline bench at 45° and attach a rope handle to a high cable. The starting position is with the elbows high and slightly bent. I find it most comfortable to prop my feet on the base of the cable machine.
Very slowly pull the rope back, keeping the elbows high and wide, until the rear deltoids are fully contracted. As you pull the rope back, arc the elbows slightly out to ensure that the rear deltoid (and not the upper trapezius) does the work. Rest your head on the bench to eliminate the chance of injuring neck muscles. Perform 8 - 12 repetitions using slow, controlled movements.
