Background/Purpose: Epidemiological studies indicate participation in light physical activity (LPA) is positively associated with psychological wellbeing. For patients with Rheumatoid Arthritis (RA), reduced functional ability may result in lower LPA engagement and consequently, compromised mental health. In particular, lower-limb physical dysfunction in RA may result in a reduced ability to transition from a sitting (or sedentary) to a standing posture (i.e., ‘sedentary breaks’), contributing towards lower LPA engagement. Since physical dysfunction is symptomatic of RA, it is also important to determine modifiable correlates of LPA. Studies framed by Self-determination Theory demonstrate autonomy supportive social environments to be relevant to levels of physical activity engagement in healthy and patient populations. Thus, the social environment may represent a malleable target for interventions that seek to promote LPA in RA. The primary aim of this study was therefore to test a model examining the implications of 1) functional disability to ‘rise’, and 2) autonomy support for physical activity, for levels of objectively assessed LPA and associated psychological wellbeing.

Methods: RA patients (N = 50, Mage = 55.5 ± 12.5 yrs), completed questionnaires assessing; 1) functional disability to ‘rise’ [e.g., are you able to stand up from an armless straight chair, higher score = lower function], 2) autonomy support for PA [from a patient-specified important other], 3) depressive symptoms, and 4) subjective vitality. Sedentary breaks and LPA engagement were determined from 7-days of accelerometry (i.e., sedentary breaks, interruptions in sedentary time with ≥1 min activity ≥100 counts/min, LPA, activity 100 – 2019 counts/min).

Results: Path analyses supported a model (χ² (5) = 8.83, p =.12, CFI =.95, SRMR = .08, RMSEA =.13), in which functional disability to rise significantly negatively predicted the number of sedentary breaks (per/hour), which in turn, significantly positively predicted LPA engagement (min/hour). A significant positive association between important other autonomy support and LPA was observed, independent of functional disability ‘to rise’. LPA then significantly and negatively predicted depressive symptoms. The association between LPA and subjective vitality was positive and approached significance (p =.06, Figure 1).

Conclusion: Functional disability to ‘rise’ may be adversely related to levels of LPA engagement in RA, via the patient’s ability to transition from sitting to standing. However, autonomy support from an important other may represent a modifiable target for interventions seeking to promote LPA, independently of the negative consequence of lower limb functional disability. Subsequently, LPA engagement may hold positive implications for psychological health in RA. Figure 1: Data fit of the hypothesised model Note: * p < .05, ** p <.01