Differences in long-term physical activity trajectories among individuals with chronic widespread pain: A secondary analysis of a randomized controlled trial.

Background: Little is known about long-term physical activity (PA) maintenance in those with chronic widespread pain (CWP) following an exercise intervention. This study examined PA over time to identify the existence and characteristics of subgroups following distinct PA trajectories.

Methods: Data come from individuals with CWP who took part in a 2 × 2 factorial randomized controlled trial, receiving either exercise or both exercise and cognitive behavioural therapy treatment. Information, including self-report PA, was collected at baseline recruitment, immediately post-intervention, 3, 24 and 60+ month post-treatment. Analyses were conducted on 196 men and women with ≥ 3 PA data points. Group-based trajectory modelling was used to identify latent PA trajectory groups and baseline characteristics (e.g., demographics, pain, self-rated health, fatigue, coping-strategy use and kinesiophobia) of these groups.

Results: The best fitting model identified was one with three trajectories: "non-engagers" (n = 32), "maintainers" (n = 144) and "super-maintainers" (n = 20). Overall, mean baseline PA levels were significantly different between groups (non-engagers: 1.1; maintainers: 4.6; super-maintainers: 8.6, p < 0.001) and all other follow-up points. Non-engagers reported, on average, greater BMI, higher disabling chronic pain, poorer self-rated health, physical functioning, as well as greater use of passive coping strategies and lower use of active coping strategies.

Conclusions: The majority of individuals with CWP receiving exercise as part of a trial were identified as long-term PA maintainers. Participants with poorer physical health and coping response to symptoms were identified as non-engagers. For optimal symptom management, a stratified approach may enhance initiation and long-term PA maintenance in individuals with CWP.

Significance: Chronic pain can be a major barrier to engaging in exercise, a popular self-management strategy. Our findings identify three distinct long-term physical activity trajectories for individuals receiving the same exercise intervention. This suggests an approach by health care providers which identifies individuals who would benefit from additional support to enhance initiation and long-term physical activity maintenance could deliver better outcomes for such patients.