Lie on the floor, on your right side, with a dumbbell in front of you and with your head being supported by your right hand.
Grasp the dumbbell with your left hand using a neutral grip (palm facing downward). Your elbow should be either straight or slightly flexed.
Execution
Keeping your elbow fixed and your body still, exhale as you raise the dumbbell from floor until it is almost vertical.
Hold for a count of two.
Inhale as you reverse the movement and lower the dumbbell towards the starting position, stopping before the dumbbell touches the floor.
Repeat for the prescribed number of repetitions.
Repeat the exercise on your opposite side, with your right arm.
Comments and tips
Keep your body still and your elbow either straight or slightly flexed.
Do not allow the dumbbell to touch the floor.
In order to target your posterior deltoid, your torso must be horizontal and your upper arm must remain perpendicular to your torso.
Instead of lying on the floor, you can lie on a bench.
The side-lying reverse dumbbell fly is also known as the side-lying dumbbell rear delt raise, the side-lying dumbbell rear lateral raise, and the side-lying dumbbell rear delt fly.