Holding a dumbbell in one hand, lie prone (on your front) on a flat bench. Ideally, the bench should be elevated to allow the dumbbell to hang straight down without touching the floor.
Spread your legs and plant your feet firmly on the floor.
Grasp the bench with your free hand for stability.
Execution
Keeping your elbow slightly bent, exhale as you raise the dumbbell out to the side.
Hold for a count of two.
Inhale as you lower the dumbbell to the starting position in a controlled manner.
Repeat for the desired number of repetitions.
Repeat the exercise with your opposite arm.
Comments and tips
Keep the bend in your elbow to a minimum.
You are free to use either a neutral grip (palm facing inward) or a supinated grip (palm facing upward). For shoulder safety, avoid using a pronated grip (palm facing downward).
Instead of grasping the bench with your free hand, put your free hand behind your back. This will put your body off balance and force the recruitment of more stabilizer muscles, especially in your core.
To target your posterior deltoid and avoid the involvement of your latissimus dorsi while performing the lying dumbbell one-arm rear lateral raise, your upper arm must rise in a path that is perpendicular to your torso (that is, directly out to the side).
To target your posterior deltoid and minimize the involvement of your lateral deltoid, your torso must be horizontal.
