STARTING POSITION:
Select the appropriate resistance in the weight stack. Stand up straight with your left shoulder pointing to the pulley. There should be a handle that is attached to a pulley higher than your head. Grab it with both hands. Contract your pelvic floor and core while keeping your chest up.
MOVEMENT:
With a fast trunk rotation, move the handle towards the floor and your right side while you exhale. Return to the starting position in a smooth movement while you inhale. Repeat the movement for the specified amount of repetitions and then repeat with the other side. The gaze should be always on the handle.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form. While your are doing the exercise, move only the shoulder joint, make sure you don't move any other part of your body.