Thanks for your thoughts Kevin,
The reason I thought the classes might be good is because they involve at lot of deep breathing and yoga-like exercise as well as plenty of stretching and concentration on posture and muscel toning. It is not gym as in weights, rowing machines, treadmills etc.

I used to regularly do sport, fitness, swimming and yoga, but have not done any exercise really since my C-section 2 years ago which really made my fitness levels hit an all time low.

I suppose what I am really asking is: could doing the type of exercise i am doing in my class actually make my AS worse and cause me physical damage?
It seems to be making me feel better (stamina/breathing/flexibility/toning) and worse (AS sites aggrevated as mentioned) at the same time.

I suppose I feel I want to try and do something more than just walking to improve my fitness (swimming is out for me in the winter as I have no pool to go to) and I love the social aspect of meeting my friends and it is in the evening and gives me the only break I get from the house and children. There is not too much going on in this area and it is very rural.

KickAS and help others do the same!