Abstract

Background: Axial spondyloarthritis (axial SpA) is a chronic inflammatory disease that primarily affects the axial skeleton. Many individuals with axial SpA have a reduced cardiorespiratory fitness (CRF) which may be affected by physical activity (PA), sedentary behavior (SB), and exercise. However, the association between these factors is not clear, in a group that already fulfilled the recommendations of PA and were instructed to maintain these.

Aim: The aim of this study was to explore different associations between self-reported PA, SB and exercise with CRF. The secondary aim was to study changes in self-reported PA, SB and exercise after 12 weeks of high-intensity interval training (HIIT) intervention in individuals with axial SpA compared with a control group.

Methods: Fifty participants with axial SpA were randomized into a HIIT (n=25) or control group (n=25). Baseline and 12 week follow up data were collected through self-reported surveys for PA, SB, and exercise, and a submaximal cycle test for estimation of maximal oxygen consumption (VO2max) was done at baseline. Pearsons correlation analyses and a two-way ANOVA was used to determine associations and group x time interactions. 

Results: At baseline the mean age of the participants was 41.3 years (±13.0), with a mean estimated VO2max of 35.2 (±7.7) mlO2/kg/min. Self-reported exercise showed a significant correlation with VO2max (r=0.351, p=0.013), while PA and SB were not significantly associated with CRF at baseline. After 12 weeks, a significant increase in self-reported exercise was observed in the HIIT group (p=0.03), however no significant change was found for PA or SB in either group. 

Conclusion: A higher self-reported level of vigorous-intensity exercise was associated with higher CRF, as reflected by VO2max, in individuals with axial SpA, while moderate-intensity PA and SB had no significant association with CRF. The self-reported exercise levels increased after the intervention for participants in the HIIT-group. However, self-reported measures may be limited in that they can misrepresent the actual changes.