Assessment of exercise‐induced hypoalgesia in chronic low back pain and potential associations with psychological factors and central sensitization symptoms: A case–control study

• Published in: Pain practice Vol. 23; no. 3; pp. 264 - 276
• Main Authors: Patricio, Philippe, Mailloux, Catherine, Wideman, Timothy H., Langevin, Pierre, Descarreaux, Martin, Beaulieu, Louis‐David, Massé‐Alarie, Hugo
• Format: Journal Article
• Language: English
• Published: United States 01.03.2023
• Subjects: Case-Control Studies; Central Nervous System Sensitization; central sensitization; Chronic Disease; chronic low back pain; Chronic Pain; exercise‐induced hypoalgesia; Humans; Hypesthesia; isometric contraction; Isometric Contraction - physiology; Low Back Pain; Pain Perception - physiology; Pain Threshold - physiology; psychological factors; chronic low back pain; exercise-induced hypoalgesia; central sensitization; isometric contraction; psychological factors
• ISSN: 1530-7085; 1533-2500
• DOI: 10.1111/papr.13189

Introduction Exercise is the most recommended treatment for chronic low back pain (CLBP) and is effective in reducing pain, but the mechanisms underlying its effects remain poorly understood. Exercise‐induced hypoalgesia (EIH) may play a role and is thought to be driven by central pain modulation mechanisms. However, EIH appears to be disrupted in many chronic pain conditions and its presence in people with CLBP remains unclear. As people suffering from chronic pain often exhibit psychological factors and central sensitization symptoms influencing pain perception, EIH might be associated with these factors. Objective The aim of this study is to compare the level of EIH between participants with and without CLBP following back and wrist exercises and to assess the associations between EIH, psychological factors, and symptoms of central sensitization (using the central sensitization inventory ‐ CSI) in CLBP. Method Twenty‐eight participants with CLBP and 23 without pain were recruited. Pressure pain thresholds (PPT) were measured at 4 sites (2 bony sites = capitate, S1|2 muscle sites = wrist flexors, lumbar erector spinae) before and after each of two exercises (wrist flexion and lumbar extension). Exercise‐induced hypoalgesia was defined as percent change in PPT from pre‐ to post‐exercise. Participants with CLBP also completed questionnaires to measure psychological factors (e.g., kinesiophobia, catastrophizing, anxiety, and self‐efficacy) and symptoms of central sensitization (CSI), and correlations with EIH were calculated. Results After wrist exercise, EIH measured at the muscle sites was lower in the CLBP group compared with the pain‐free group (p = 0.047) but no differences were found at bony sites (p = 0.49). No significant differences for EIH were observed following back exercise at muscle sites (p = 0.14) or at bony sites (p = 0.65). Exercise‐induced hypoalgesia was not correlated with any psychological factors or with the CSI score. Conclusion The lower EIH following wrist exercises may represent an alteration in pain modulation control in CLBP. However, psychological factors and central sensitization symptoms may not explain the differences observed.