A reverse crunch is done in a few simple steps. It focuses on the lower abdominal muscles and does not put stress on the neck like other abdominal exercises can.
Begin by laying flat on the floor with your knees at a 90 degree angle and your palms flat on the floor by your side.
Using your lower back, pull your legs up in and "sitting" position.
Continue pulling your legs toward your chest as far as you can while "crunching" your abs. Elevate your lower back in the air while keeping your shoulders firmly onto the floor. Remember to exhale during this motion.
Slowly lower your legs back into the starting position while inhaling.
Return to the starting position and repeat. For best results do 3 sets 15-20 reps.