The deltoids are composed of three portions: the front (anterior), side (lateral), and the rear (posterior). Well-developed front delts are common among weightlifters because they’re highly involved in pressing movements such as dips, chest press, and shoulder press. Another reason? People tend to pay more attention to muscles they can see in the mirror. Well-developed rear delts, on the other hand, are far less common. Not only are they out of sight, out of mind, but they’re also more difficult to achieve.
The primary action of the rear delt is to bring the arm from front to back in the horizontal plane with the elbows high and out. Wide-grip rows to the chest, bentover laterals, reverse pec decks, and, in particular, lying laterals—a great isolation exercise—all hit the rear delts.
To get the most out of your lying laterals, keep the plane of motion perpendicular to the body, raising and lowering the dumbbell directly in front while keeping the elbow, and pinkie, turned up. Do not attempt to go heavy. In fact, only the use of light weight will allow you to execute proper form.
