The woman behind the product, Leslee Bender, says that using this little green ball to perform a variety of abdominal and Pilates-type exercises is 408 percent more effective than regular crunches. Bender says a regular crunch is a rather limited exercise, since you can only move forward and not backward. But with the Bender Ball placed beneath your lower back, you're getting both extension and flexion, which you'll do in three different levels on the workout DVD that comes with your order. From start to finish, the workout is about 15 minutes and targets all of the muscles in your core.