STARTING POSITION:
Find a Smith machine with the bar at your hip height. Place a bench in front of the bar. Grab the bar with supinated grip lean back. Maintain your body in a straight line and your arms fully extended retracting your shoulder blades. Place your feet together on the bench so your body is parallel to the floor. Contract your pelvic floor and core while keep your body straight.
MOVEMENT:
Pull the bar towards your torso until your hands are next to your ribs while you exhale. Return to the starting position with a smooth movement while you inhale. Make sure your shoulder blades are always retracted.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form. Alter your grip (neutral, pronated, supinated..) from time to time to train the muscles from multiple angles.