One hundred patients with axial spondyloarthritis were randomized to receive 12-week high intensity exercise program, or standard care with maintenance of usual physical activity levels. The primary outcomes of interest included disease activity measured by the Ankylosing Spondylitis Disease Activity Score (ASDAS), C-reactive protein (CRP) levels, and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) total score and sub-scores (neck/back/hip pain, peripheral pain, morning stiffness, morning stiffness duration, fatigue, and tenderness). Additional outcomes of interest included physical function via the Bath Ankylosing Spondylitis Functional Index (BASFI), spinal mobility via the Bath Ankylosing Spondylitis Metrology Index (BASMI), estimated peak VO2, maximum and resting heart rate, maximal effort, weight, BMI and waist circumference. All outcomes were measured at 3 months follow-up. The results demonstrated that all primary outcomes were statistically significantly in favour of the high intensity exercise intervention (p<0.05 for all), with the exception of BASDAI tenderness sub-score (p=0.059). For secondary outcomes, BASFI scores (p<0.001), BASMI scores (p=0.016), estimated peak VO2 (p<0.001), and waist circumference (p=0.031) were all statistically significantly in favour of the high intensity exercise group.