ouraged to exercise 4060 minutes three times a week for twelve weeks. Twice a week the exercise sessions were carried out at a fitness center with individual supervision from a physical therapist. These sessions consisted of both endurance and strength training. The endurance High Intensity Exercise in Axial Spondyloarthritis on a 10 point numeric rating scale, and a sum score was calculated. Spinal mobility was measured by Bath AS Metrology Index . BASMI includes five objective measurements of spinal mobility, and the score PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19720342 is 010 for each component, and the mean of the five scores produced a BASMI score from 010. Cardiorespiratory fitness. Cardiorespiratory fitness was assessed with a maximal walking treadmill test for estimation of peak oxygen uptake as previously described. Resting HR was measured after at least five minutes rest in a supine position and several recordings were made until two measurements differed by 5 heart beats, and the mean was then calculated. Arterial stiffness. We measured arterial stiffness after at least five minutes of rest in a supine position, using the Sphygmocor apparatus. Several recordings were made from each patient and only those of high quality, according to standardized criteria, were chosen for further analyses. Augmentation Index was estimated through pulse wave recordings at the radial artery. The pulse waves of the central arteries were derived by applying a validated transfer factor. For measurements of Pulse Wave Velocity, we recorded the pulse at the carotid artery and the femoral artery. The distance between these points was measured. The time of wave travel was simultaneously recorded with electrocardiogram. PWV was calculated by dividing the distance with the time, expressed in m/s. Body composition. Body weight and body height were measured with calculation of body mass index . Waist circumference was measured with a measuring tape at the height of umbilicus with the patient lying in supine position. Dualenergy X-ray absorptiometry was used to assess body composition and DXA is KU55933 reconized as a validated reference method for assessing body composition. Blood pressure. Brachial BP was measured in a supine position after at least five minutes rest using Omron M7. Several measurements were performed until two differed by 5 mmHg in both systolic and diastolic BP and the average of these two measurements were calculated. Inflammatory markers, cytokines and lipids. Blood samples were drawn after at least four hours fasting, and at PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19718802 least 48 hours after the last exercise session, and then analyzed for CRP, total cholesterol and high density lipoprotein cholesterol by 
COBAS 6000. Low density lipoprotein cholesterol was calculated from Freidewalds formula. Erythrocyte sedimentation rate was measured using the Westergren method. In addition, blood samples were collected in EDTA containing vacutainer tubes, plasma were isolated and frozen at 280uCelsius and batch analyzed by enzyme immunoassays. The following were analyzed: interleukin -6, IL-23, IL-17a, IL-18 and soluble TNF receptor 1 and 2 at the end of the study. The inter- and intraassay coefficients of variation were less than 10% for all EIAs. Safety. Safety was considered as absence of a flare up in disease activity and was defined in terms of stable or decreased self-reported disease activity and acute phase reactants. Further, we included the report of any adverse events in the definition of safety. Randomization and blinding Allocation to