STARTING POSITION:
Select the appropriate weight of the dumbbells. Lie on a fitball facing down, it should be under your stomach. Your feet should be touching the floor. Your head should facing down. Maintaining the natural arch of your back, place the dumbbells in front of you using a pronated grip. The arms should be perpendicular to the floor. Retracting the shoulder blades, pull the dumbbells up to the sides of your chest while you exhale.
MOVEMENT:
Without moving any other part of the body, do an external rotation of your shoulders to lift the weights until the arms are parallel to the floor. Return to the starting position with a smooth movement while you inhale.
TIPS: While your are doing the exercise, move only the arms, make sure you don't move any other part of your body. The exercise key is quality over quantity. The trick is to perform the exercise using proper form.