I want to tell few things about swiss ball...five years ago when I had major AS attack which lasted more than three months swiss ball put me back on my feet and was my incredible help. The most immpoftant thing about this ball is to use it in the way it suits you. If it is to hard for you pump it out, if it is too soft pump it up. Use it as support, dont make heavy exercises in the first time. Just lay over it and breathe, let your spind extend and your muscle stretch. Sit on the ball hold your knees at 90 degrees angle and look straight, try to stay in that position for 15 seconds and breathe...if floor is too hard for you use mattress, lay on your back an put your legs on the ball to extend your leg muscles. As time passes you will be more familiar with ball and allow yourself to try harder exercises.