Background/Purpose: Rheumatoid arthritis (RA) may cause joint damage leading to physical dysfunction and associates with increased cardiovascular (CV) risk. Regular physical activity (PA) can attenuate disease-related symptoms and improve function. Self-Determination Theory (SDT), a contemporary theory of motivation, has provided the foundation for PA promotion interventions among different patient groups but has not been applied to facilitating PA engagement in people living with RA.  Objectives: To examine whether a 3-month SDT-based exercise intervention can lead to improvements in cardiorespiratory fitness (CRF, primary outcome), self-reported moderate PA, self-reported sitting time, functional disability and self-determined motivation towards PA participation in patients with RA.

Methods: Data were collected as part of the Physical Activity in Rheumatoid Arthritis (PARA) randomised controlled trial. The PARA study compared the effectiveness of two 3 month exercise programmes in N = 115 patients with RA (Mage = 54 ± 12.5 yrs). Patients in the experimental (N = 59) and control (N = 56) arm, both received the same gym-based exercise programme which was tailored for people with RA. However, the experimental arm also received one-on-one SDT informed consultations by a trained advisor that aimed to foster more self-determined motivation for PA. Assessments were carried out at baseline, 3, 6 and 12 month follow-up. Data analysed for the present work is from measures taken at baseline and at 3 months (immediately post intervention). CRF was assessed via an exercise tolerance test. Self-reported moderate PA, sitting time, functional disability and self-determined motivation for PA were measured using validated questionnaires. Repeated measures analyses of covariance (ANCOVAs) were conducted to examine main effect and group x time effects on targeted outcomes. Analyses were adjusted for age and exercise programme attendance.

Results: No significant group x time interactions were observed for cardiorespiratory fitness or functional disability. Significant interactions between groups were observed for: self-reported moderate PA (min/week) (F (1) = 4.31, p < .05), daily sitting time (min/day) (F (1) = 4.93, p < .05), and self-determined motivation for PA (F (1) = 5.72, p < .05). Specifically, favourable changes were seen in for these outcomes in the experimental, relative to the control arm (Table 1).  

Conclusion: These findings suggest that a SDT-grounded PA intervention promotes adaptive motivational processes that may encourage increased engagement in moderate intensity PA in RA patients involved in a tailored exercise programme. However, more structured exercise interventions with additional support may be required to promote increases in PA engagement towards levels required to improve CRF in people living with RA. Table 1. Descriptive statistics