Hi Postal,
I think fusing is the end result of AS.After the spine is fused then other problems will accur especially in the chest area and the lungs. I exercise to prevent that from happening. Before I was diagnosed I always exercised so altho I am totally fused I have no shoulder, knee or hip problems.
Once in a while I may get a little pain in the heel and right hip but I get into the gym and work it out.
Seems that along with medication, exercise is the best thing for AS.

Hope you were able to get some answers here.

Take care,
Doreen