Acute Effects of a High-Intensity Interval Training Protocol on Pain Sensitivity and Inflammatory Markers in Persons with Chronic Nonspecific Low Back Pain: A Controlled Clinical Trial

Chronic nonspecific low back pain (CNSLBP) might be associated with increased pain sensitivity and inflammation. High-intensity interval training (HIIT) has been suggested to reduce pain outcomes and inflammatory markers, but its effects compared to moderate-intensity continuous training (MICT) remain unclear. This study aimed to evaluate the acute effects of HIIT on pain sensitivity and inflammatory markers in persons with CNSLBP compared to healthy controls (HCs) and to determine how these effects differ from MICT. Twenty persons with CNSLBP and twenty HCs were assessed before (PRE) and after (POST) a single HIIT and MICT protocol for pain sensitivity (cuff pressure pain threshold (cPPT), temporal summation of pain (TS), conditioned pain modulation (CPM)), and inflammatory markers (IL-6, TNF-α). Data were analyzed using one-way ANOVAs, paired t-tests, and correlation analyses. At PRE, persons with CNSLBP exhibited lower cPPT (28.2 ± 7.1, Δ = −5.5, p = 0.040), higher TS (1.11 ± 0.89, Δ = 0.79, p = 0.042), and lower CPM (36.2 ± 11.6, Δ = −10.0, p = 0.023) compared to HCs. HIIT resulted in PRE–POST improvements in cPPT (38.9 ± 12.6, Δ = 5.2, p = 0.019) in HCs. No PRE–POST differences were observed in pain processing in those with CLBP. No PRE or PRE–POST differences were observed in the inflammatory markers in either group. The current exploratory study suggests that a single HIIT session might have a beneficial effect on pain sensitivity in HCs but does not alter acute pain sensitivity or inflammatory markers in persons with CNSLBP. Further research is needed to clarify the involved mechanisms and explore the (relation with the) long-term effects of HIIT.