Grant: Project Grant

It is estimated that approximately 20% of the Canadian population is currently suffering from chronic pain. Amongst the different chronic pain syndromes, chronic low back pain (CLBP) is by far the most prevalent, and the one responsible for the most years lived with disability. Alas, we still have a limited understanding of the factors contributing to pain chronicity. Consequently, most current treatments only have modest effects on CLBP. However, in recent years, evidence has mounted to support the effectiveness of physical exercise as a treatment for CLBP. Unfortunately, we know very little of the physiological mechanisms underlying the impact of exercise therapy on CLBP. Indeed, because the backs of most CLBP patients (~85%) do not show any particular signs of pathology explaining the persistence of the pain, it has been proposed that CLBP may be principally maintained or amplified by the central nervous system (CNS, i.e. brain and spinal cord). The objective of the proposed project will therefore be to investigate the CNS mediators of the effects of exercise therapy on CLBP. More specifically, we hypothesize that physical exercise will reverse the stress-related central inflammation and hippocampal atrophy associated with CLBP. In order to test this hypothesis, 100 patients with CLBP and 100 age-matched controls will be tested before and after a 16-week long physical exercise intervention (3 x 1 hour of high intensity aerobic and muscular exercise per week). Blood draws will be taken to measure circulating levels of pro- and anti- inflammatory molecules, and magnetic resonance imaging (MRI) will be used to measure the volume and connectivity of several brain structures, including the hippocampus. Finally, half of the participants will start the study with a 16-week long period without exercise training in order to control for time and other non-specific effects of exercise therapy.