Performing the: A Step-by-Step Tutorial Dumbbell One Arm Reverse Fly
Extend the arm with the dumbbell straight down from your shoulder, keeping a slight bend in your elbow.
Keeping your torso still, lift the dumbbell out to the side and up until it is level with your shoulder, maintaining the slight bend in your elbow throughout the movement.
Pause for a moment at the top of the movement, then slowly lower the dumbbell back down to the starting position.
Repeat the exercise for your desired number of reps, then switch hands and perform the same number of reps with the other arm.