Grip the pull-up bar with your hands just outside of shoulder-width and allow your body to comfortably hang down. As you roll your pelvis forward, raise your legs up until they are slightly lower than parallel to the ground. Make sure to keep your lower back slightly rounded rather than arched. Pause briefly at the top of the motion and then lower your legs back down to the starting position in a controlled manner. Continue until you reach muscular failure.
Tips:
Keep a slight bend in your legs as you perform your repetitions because this will keep the tension on your abs at all times. It is also important to avoid using body momentum or swinging motions to lift your legs up. You can place a dumbbell in between your feet to add extra resistance, although this can sometimes feel awkward.
