Holding a pair of dumbbells, sit on the end of a bench.
Lean forward until your torso is as close to horizontal as possible and allow your arms to hang down by your feet. Your palms should be facing each other (neutral grip).
Keeping your arms slightly bent and your elbows perpendicular to your torso, exhale as you raise your arms out to the sides until your elbows are shoulder height.
Hold for a count of two.
Inhale as you lower your arms to the starting position in a controlled manner.
Comments and tips
Keep your back straight and your elbows higher than your wrists.
Control the movement. If you find yourself having to swing the dumbbells up, you’re using too heavy a weight.
Keep your torso as close to horizontal as possible. This ensures that you target your posterior deltoid instead of your lateral deltoid.
Keep your elbows perpendicular to your torso (i.e. straight out to the sides). This will minimize the involvement of your latissimus dorsi.
You can perform this exercise while standing, with your torso bent over horizontally (reverse dumbbell fly). However, the seated reverse dumbbell fly, described above, reduces your ability to cheat by reducing the extent to which your body can sway up and down.
The seated reverse dumbbell fly is also known as the seated bent-over dumbbell lateral raise, the seated dumbbell rear lateral raise, and the seated dumbbell rear delt fly.