The deltoids are composed of three heads — anterior (front), middle and posterior (rear). All three are important in not only moving the shoulder in an infinite number of ways, but also in giving the deltoids their cannonball shape. Unfortunately, the middle and front delts get all the attention when it comes to training, with the rear delts being an afterthought. This leads to imbalances in deltoid development and in shoulder strength, which could result in injury. A simple solution is to do a few sets of standing cable reverse flyes at the end of shoulder workouts. Stand in the center of a cable crossover station with your hands crossed in front of you at shoulder height, the left high cable in your right hand, the right in your left hand. Using your rear delts, pull your elbows out and back as far as possible. Hold the finish position for a second or two, contracting the rear delts. Repeat.
WHEN TO WORK REAR DELTS
The best time to focus on the rear deltoids is at the end of your shoulder workout, after you have trained your middle and front delts. Exercises that focus on the middle and front deltoids are the major mass builders. If you do rear delt exercises first, you make them the weak link for the other exercises, forcing you to use less weight and place less overload on your delts.
FORM AND FUNCTION
The rear or posterior head of the deltoid is located closest to the back of the body. This muscle starts from the scapula (shoulder blade) and attaches to the common tendon that is shared by the other two deltoid heads, appended to the humerus (upper arm bone). The rear deltoid head extends the upper arm back, as during rear delt raises or cable reverse flyes.
