Effects of a single exercise session on pain intensity in adults with chronic pain: a systematic review and meta-analysis

Background: Chronic pain is prevalent amongst society, making it necessary to find strategies to manage chronic pain. Regular exercise is efficacious; however, pain is a barrier to initiating exercise. A single exercise session is also believed to acutely reduce pain, however, the evidence for this is less robust. Objectives: This systematic review and meta-analysis aimed to identify the effect of a single exercise session on pain intensity in adults with chronic pain. Methods: We searched eight databases and trial registries to identify randomised controlled trials evaluating the effect of a single exercise session on pain intensity in adults with chronic pain compared to a non-exercise control. Literature screening, data extraction, risk of bias (Cochrane 2.0) and quality assessment (GRADE) were conducted independently and in duplicate. Random-effects meta-analyses were performed using the metafor package in R. Results: We included 17 trials (46 study arms with 664 adults [44% female]). There were no significant differences in pain intensity (mean difference on a 0-10 scale) immediately post-exercise -0.02 (95% CI = -0.06, 0.62; I-2 = 77.1%) or up to 45-min post-exercise -0.17 (95% CI = -0.49, 0.16; I-2 = 34.2%). All trials were at high risk of bias and the overall confidence in these findings was very low. Conclusion: A single exercise session did not reduce pain intensity up to 1-h post-exercise. Notably, increases in pain were not observed either, suggesting that while pain can be a barrier to initiating exercise, clinicians can educate patients on the unlikelihood of exercise acutely increasing pain intensity.