Objective
To evaluate cardiopulmonary function and maximal exercise capacity in patients with ankylosing spondylitis using exercise stress test, the possible causes of reduced maximal exercise capacity and the correlation between dynamic pulmonary function and static pulmonary funtion

Method
Twenty patients with ankylosing spondylitis were evaluated with incremental exercise stress test, static pulmonary function test and the mobility of thoracic cage and spine.

Results
1) Nineteen patients (95%) showed reduced maximal exercise capacities. 2) Deconditioning was the most frequent cause of reduced maximal exercise capacities (13 patients, 68%). 3) There was no significant correlation between exercise stress test and static pulmonary function test, and between exercise stress test and the mobility of the spine and thoracic cage.

Conclusion
Maximal exercise capacities were reduced in patients with ankylosing spondylitis, and the most frequent cause of them was deconditioning. To improve exercise capacity, conditioning exercise should be emphasized in patients with ankylosing spondylitis.