Neurobiological and Psychological Benefits of Exercise in Chronic Pain and PTSD

Inclusion Criteria: * Only Veteran and civilian participants in whom a physical examination, medical history, EKG, and baseline laboratory studies including urine toxicology screens indicate that maximum load exercise testing will be safe will be included in this study. * Participants must be free of medications and other substances, (e.g., illicit drugs and alcohol) with effects that could hinder data interpretation for 2-6 weeks depending on the medication and frequency of use (which must be cleared by the PI's primary mentor). * If on pain medications with short half-lives, must be off of them for 5 half-lives before testing, generally about 24 hours. * Any participant with an ICD9 chronic pain diagnosis, with a musculoskeletal etiology, as confirmed by the study rehab medicine doctor, will be allowed for inclusion in the study. * Also, any participant with a confirmed psychiatric diagnosis of PTSD * or have trauma exposure without a diagnosis of PTSD but some symptoms of PTSD, including subthreshold PTSD * other psychiatric conditions * Individuals must meet for current chronic PTSD (\>3 months ) as assessed by the CAPS 1-Month Diagnostic Version. Exclusion Criteria: * Veteran and civilian participants will be excluded from participation in the study if they have: * a life threatening or acute physical illness (e.g., cancer) * current schizophreniform illnesses or bipolar disorder * or active suicidal or homicidal ideation requiring clinical intervention. * Women participants who are pregnant or are intending to become pregnant within the next six months will be excluded from participation. * Individuals with current or past alcohol and/or substance dependence (less than three months from date of screening assessment) will be excluded. * individuals without PTSD who have had greater than one major depressive episode or diagnosis of another serious psychiatric illness in their past, e.g.: * bipolar disorder or a schizophreniform disorder except for Psychosis not otherwise specified due to PTSD-related sensory hallucinations. * Individuals seeking pain treatment such as surgical interventions or who have a neuropathic origin to their pain will also be excluded. * Participants with chronic pain concerns that cannot tolerate exercising in a reclining bike and those who have had a clinical history of coronary artery disease or positive stress test * Uncontrolled cardiac arrhythmia * Moderate-to-severe aortic stenosis * Severe arterial hypertension (systolic…