Hi Jay,
Exercise, with AS, is mainly used to prevent reduced range of motion, prevent inflamation from building up, and preventing fusion from happening too. THe more the joint moves, the less the AS can fuse the joint together. Exercise can, and most often does, reduce pain from inflammation as well. Exercise also helps circulate blood and oxygen within the joints and helps break away any already solidified deposits, and calcification, left behind that are created by inflamation and the fusion process. It also helps secrete inflamation out of the joint and tissues involved.
Yes it is possible to reduce meds due to a good exercise routine.
Exercise is a very important part of treating AS. Although, over-exercising or pushing to far presents a problem for many of us, it can actually cause severe pain and inflammation in an AS involved joint. The main thing we all need is keeping our joints stretched as much as possible, without going overboard. Of course the level or amount of exercise will vary from person to person.
One more thing about exercising and AS. Exercise is also good for our muscles (of course). We need to keep them strong and flexible to be able to handle the stiffening joints, and to prevent them from becoming severely weakened from lack of movement. In some cases a stiff joint can cause the muscles to tighten up and strain too.
As you can see, exercise to me is important. I am not very 'able-bodied' anymore, but I am still doing every little bit I can when I can so it doesn't get any worse.
P.S. If you feel like some exercise is too much for you, and it leads to pain afterwards, then it probably is too much exercise. Go at your own pace, don't force it, just keep your joints active, and maintain good health.
Take care,
James.