Acute Effects of High Intensity Training on Pain Processing and Inflammation in Chronic Low Back Pain.

A multitude of exercise therapy modalities are effective in improving daily physical function and relieving pain in various forms of chronic musculoskeletal pain (CMP) such as chronic neck pain, osteoarthritis, fibromyalgia, and chronic low back pain. However, the inital pain response to physical exercise can be variable in populations with CMP. Indeed, some studies show no change or even brief exacerbations in pain in individuals with CMP in response to exercise. These pain flare-ups in chronic pain populations are believed to be associated with increased pain sensitivity after exercise. The magnitude of \"exercise-induced hypoalgesia\" or the EIH response (i.e., the short-term endogenous pain-suppressing response after exercise) is believed to depend on several training factors, including exercise intensity. Currently, there is limited understanding of the optimal intensity of exercise for producing hypoalgesic effects on different types of pain stimuli. Nevertheless, several indications have been found for a dose-response effect in exercise and the amount of EIH that can be expected. However, very few studies have specifically examined EIH in people with chronic low back pain, although exercise is recommended in national and international guidelines as a basic treatment for the treatment of this condition. Relevant studies have also shown that exercise can induce an extensive inflammatory response in CMP, which may contribute to the disrupted EIH production. In addition, it is stated that this inflammatory response in CMP is also influenced by psychosocial factors. Therefore, the aim of the current cross-sectional cohort study is to expand the knowledge of the pain processing and inflammatory response to acute physical exertion in persons with chronic low back pain through evaluation responses of persons with this disorder to a high intensity training protocol. It is also investigated whether their EIH response is dependent on psychosocial factors.