Abstract
Engaging in physical activity (PA) is a key aspect in the management of axial spondyloarthritis (axial SpA), however, its relationship with clinical measures is unknown. Previous research has mainly focused on subjective methods of measuring PA and sedentary behaviour (SB). The aim of this study was to explore the associations between objectively measured PA and SB with clinical measures in people with established axial SpA. Fifty participants were recruited from secondary-care rheumatology outpatient services in Glasgow, UK. Clinical measures collected included; Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Quality of Life (ASQOL) and the Six Minute Walk Test (6MWT). PA and SB were measured using the activPAL3 tri-axial accelerometer. Data from forty-five participants were included (23 males, average age 49 ± 12 years). Participants accumulated an average of 93.2 ± 41.5 min/day walking with an average of 7200 ± 3397 steps/day. The majority of the day (65%) was spent sitting, accumulated in prolonged bouts. Walking time and steps taken/day were associated with better BASFI (r = - 0.395, p = 0.007 and r = - 0.404, p = 0.006), ASQOL (r = - 0.375, p = 0.011 and r = - 0.361, p = 0.015) and 6MWT (r = 0.396, p = 0.007 and r = 0.421, p = 0.004); while longer walking events were associated with better BASMI (rho = - 0.352, p = 0.018), BASFI (rho = - 0.316, p = 0.034) and 6MWT (rho = 0.404, p = 0.006). SB was associated with worse ASQOL (r = 0.380, p = 0.010) and 6MWT (6MWT, r = - 0.357, p = 0.016). In people with axial SpA PA is associated with better function, exercise capacity and spinal mobility, while SB is associated with lower exercise capacity and poor quality of life. These findings support the promotion of PA and reduction of SB in people with axial SpA.