The ribs can become inflammed where they attach to the spine leading to stiffness and fusion.
Inflammation of the ribs may cause pains that can be confused with the pain of cardiac or lung problems.
Anyone experiencing symptoms of chest pain should seek medical attention to rule out a more serious condition.
In normal breathing the ribs move up and down with each breath. If the ribs become stiff, the ribs rise and fall less well. This means that breathing takes place using only the flat muscle below the lungs separating the lungs from the belly (diaphragm).
You do not stop being able to breathe if the ribs fuse but tight clothing around the belly will be more uncomfortable as it will make it more difficult for you to breathe.
Breathing exercises encourage you to maintain your rib movements so you do not have to rely entirely on your diaphragm muscle.
Poor chest wall movement may result in reduced lung capacity and a few people develop scarring or fibrosis at the top of the lungs which is usually detected only by a routine chest x-ray. Sometimes people have functional lung impairment which means that it can take longer for colds and other upper respiratory infections to heal.
It is crucial that you do not smoke if you have AS.