Associations among changes in inflammatory biomarkers, pain intensity, and health-related quality of life following a 12-week aerobic exercise programme in individuals with non-specific chronic low back pain

Background Non-specific chronic low back pain (NSCLBP) is associated with persistent pain, reduced health-related quality of life (HRQoL), and low-grade systemic inflammation. This study examined associations among changes in inflammatory biomarkers, pain intensity, and HRQoL following a 12-week aerobic exercise programme. Methods This exploratory secondary analysis used data from a randomized controlled trial involving 41 participants with NSCLBP (intervention, n = 21; control, n = 20). Participants received either supervised aerobic exercise plus health education or health education alone for 12 weeks. Change scores for tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), pain intensity, and HRQoL domains were analysed using correlation and multiple regression analyses. The analyses were exploratory and were not designed to establish causal or mediating pathways. Results Improvements in IL-6 ( r = 0.434, p = 0.005) and hs-CRP ( r = 0.444, p = 0.004) were significantly associated with improvements in pain intensity. Following adjustment for multiple comparisons using the Benjamini–Hochberg false discovery rate procedure, both associations remained statistically significant (adjusted p = 0.038 for both). No significant associations were observed between biomarker changes and HRQoL domains. Treatment allocation was significantly associated with improvement in physical HRQoL (β = 0.492, p = 0.017) and pain intensity (β = −0.512, p = 0.006) in the multivariable models. Conclusions Improvements in IL-6 and hs-CRP were associated with reductions in pain intensity but not with improvements in HRQoL. Treatment allocation was significantly associated with improvement in pain intensity and physical HRQoL in the multivariable models. These findings are exploratory and do not establish that changes in systemic inflammation mediate the effects of aerobic exercise. Larger, adequately powered longitudinal studies are needed to clarify the relationships among exercise, inflammation, pain, and HRQoL in NSCLBP. Clinical trial registration Pan African Clinical Trials Registry (PACTR), Registration Number: PACTR202606887164888; retrospectively registered on 11 June 2026. The study protocol, eligibility criteria, intervention procedures, and outcome measures were established prior to participant recruitment.