While holding a dumbbell in one hand, lay with your chest down on a flat bench. The other hand can be used to hold to the leg of the bench for stability.
Position the palm of the hand that is holding the dumbbell in a neutral manner (palms facing your torso) as you keep the arm extended with the elbow slightly bent. This will be your starting position.
Now raise the arm with the dumbbell to the side until your elbow is at shoulder height and your arm is roughly parallel to the floor as you exhale. Tip: Maintain your arm perpendicular to the torso while keeping your arm extended throughout the movement. Also, keep the contraction at the top for a second.
Slowly lower the dumbbell to the starting position as you inhale.
Repeat for the recommended amount of repetitions.
Variations: You can perform this exercise with both arms at the same time and also keeping the palms of the hands facing back as opposed to facing your torso.
Alternative Exercises For Lying One-Arm Lateral Raise