Neuroimmune Responses to Exercise in Chronic Back Pain

Inclusion Criteria-CLBP patients: * Have a diagnosis of chronic primary LBP, according to the criteria established by NIH Task Force on Research Standards for CLBP (Deyo et al., 2015). This will be determined by 1) the response to the National Institutes of Health minimum dataset for CLBP (NIH-md), including that LBP has been persistent for at least 3 months or recurrent for at least half of the days in the past 6 months, and 2) the results of a complete case history and physical examination (including functional tasks, quantitative sensory testing, and, if needed, neuro-orthopedic, palpation and range of motion assessments); * Report a CLBP intensity of at least 4 in a 0-10 numerical rating scale (0 = no pain, 10 = maximum possible pain). Inclusion Criteria-Healthy controls: \- Be over 18 years and under 75 years of age; Exclusion Criteria-CLBP patients: * Present any red flags indicative of serious pathology comorbid or as the cause of CLBP (Finucane et al., 2020); * Have a CLBP phenotype characterized by predominant nociceptive (as in fracture, infection, malignancy, inflammatory or rheumatic spondyloarthropathy, cauda equina syndrome, confirmed by MRI when suspected) or neuropathic pain mechanisms, the latter assessed through score in the DN4 questionnaire (Nijs, et al., 2024); * Present chronic or acute pain of higher intensity or perceived disability in any other body site than the low back; * Medical history of diabetes, neurological or psychiatric disorder; * Presence of significant cardiorespiratory problems or any other potential contraindications to physical exercise as assessed through the Physical Activity Readiness Questionnaire for Everyone (PAR-Q+); * Following a regular structured PE training program (\>60 min/week) at study's onset, and; * Presence of any contraindications to MRI examination (including any metallic implants or devices, being pregnant, and claustrophobia). Exclusion criteria-Healthy controls: * Have symptoms or a diagnosis of any acute or chronic pain conditions; * Medical history of diabetes, neurological or psychiatric disorder; * Presence of significant cardiorespiratory problems or any other potential contraindications to physical exercise as assessed through the Physical Activity Readiness Questionnaire for Everyone (PAR-Q+); * Following a regular structured PE training program (\>60 min/week) at study's onset, and; * Presence of any contraindications to MRI examination (including any metallic implants or devices, bei…