Place the ab accessory on the rail of the GR8 about 10 inches away from the cables. Lay on the bench pad with your knee on the pad and your feet slightly elevated. Grab the ab attachment and rest your forearms on the foam pad. Start the movement by pulling your lower body into the handles by crunching. Pull the knees into the handles and squeeze your ab muscles. Allow for a brief pause at the beginning and end of every repetition to prevent swinging or the use of momentum.