Background The health benefits of physical activity (PA) in the general population are numerous and well documented1. Among adults with ankylosing spondylitis (AS) a number of structured exercise programmes have shown positive effects on clinical measures2, however few studies have objectively measured PA in an AS cohort and the effects of free-living PA are less clear3.
Objectives The aims of this study were to: 1) objectively measure PA levels of adults with AS and compare these to population controls, and 2) examine relationships between PA and condition-specific outcomes.
Methods This cross-sectional study included participants meeting the modified New York Criteria for AS, and age- and gender-matched population controls. All participants were >18 years of age. Exclusion criteria included the presence of a comorbidity limiting PA, or changes in medication use in the previous six weeks. Demographic data was recorded and participants completed clinical questionnaires including the Bath AS Disease Activity Index (BASDAI), the Bath AS Functional Index (BASFI) and the AS Quality of Life questionnaire (ASQoL). Tri-axial accelerometers, worn for one week, recorded habitual PA during waking hours. Output in counts/minute was expressed as minutes/day spent at different PA intensities. Health-enhancing PA was defined as bouts of PA lasting ≥10 minutes, performed at moderate- and/or vigorous-intensity. Group differences were examined by χ2-tests for categorical variables, and independent t-tests and analysis of covariance for continuous variables. Statistical adjustments were made for group differences in confounding variables. Associations were explored using regression analyses.
Results Seventy-eight adults were recruited into an AS and a control group (32 males and 7 females per group). Mean age was 40.0 years (SD 9.0) in the AS group and 38.9 years (SD 9.0) in the control group. Mean symptom duration was 16.6 years (SD 10.0). A significantly higher proportion of the control group were employed and had completed education to at least third level (p <.05). Four participants returned invalid accelerometry data. Daily PA is summarised in Table 1. The AS group spent significantly less time performing vigorous-intensity PA than controls [mean difference (95% CI) 1.8 minutes/day (1.1 to 2.8)], and performed significantly fewer bouts of health-enhancing PA [1.7 minutes/day (1.1 to 2.7)]. Health-enhancing PA was not statistically associated with clinical questionnaires.
Conclusions Despite exercise being a key component of the management of AS, this study found that fewer than half of adults with AS meet PA recommendations. Compared to population controls, adults with AS accumulate significantly fewer bouts of health-enhancing PA. To help address this, explorations of PA behaviour and strategies to increase PA participation in this cohort are needed.
World Health Organisation. Recommendations on physical activity for health. Geneva, Switzerland: World Health Organisation, 2010
O'Dwyer T, O'Shea F, Wilson F. Exercise therapy for spondyloarthritis: a systematic review. Rheumatol Int. 2014; 34(7): 887-902
O'Dwyer T, O'Shea F, Wilson F. Physical activity in spondyloarthritis: a systematic review. Rheumatol Int. 2014. Epub 10 Oct 2014
Disclosure of Interest None declared