Once you are laying down, move the dumbbells in front of you at shoulder width. The palms of the hands should be facing each other and the arms should be perpendicular to the floor and fully extended. This will be your starting position.
With a slight bend on your elbows in order to prevent stress at the biceps tendon, lower your arms out at both sides in a wide arc until you feel a stretch on your chest. Breathe in as you perform this portion of the movement. Tip: Keep in mind that throughout the movement, the arms should remain stationary; the movement should only occur at the shoulder joint.
Return your arms back to the starting position as you squeeze your chest muscles and breathe out. Tip: Make sure to use the same arc of motion used to lower the weights.