Training your shoulders with Rear Delt Fly Machine, Frontal and Lateral Raises and Bench Press variations may already be an important part of your routine. Those are all great exercises. But you need to work your posterior/rear deltoids, too, or risk a shoulder complex imbalance and an increased risk for shoulder injuries.
This is where the best rear delt exercises come in. The posterior deltoid actually acts more like a back muscle. It has three main functions. It’s the primary horizontal abductor (reverse fly motion) of the shoulder, and it also assists in external rotation and extension of the humerus (upper arm bone).
Aside from its postural benefits, the rear delt plays a major role as a dynamic stabilizer of the shoulder, making it a training necessity.