The seated rear lateral raise helps increase the strength and muscle growth of the posterior deltoids and upper back. The seated position allows for maximum isolation of the target muscles.
Grab a pair of dumbbells and sit on the edge of a flat bench. Allow the dumbbells to hang by your sides with your palms facing towards each other. Keeping your spine flat, bend forward until your torso is at a 45-degree angle to the ground.
Maintaining a slight bend in the elbows, raise your arms up and out to the sides until they are parallel with the ground. Pause, and then slowly return the weights back to the starting position.
Squeeze your shoulder blades together at the top of the movement
Keep your shoulder blades pulled back and down for stability.
Don't use momentum to raise the weight. Raise and lower in a controlled motion to keep the tension on your shoulders.