Exercise Induced Hypoalgesia in Pain-free Stroke and Healthy Populations: a Cohort Study

Exercise has shown multiple beneficial effects in both healthy and post-stroke populations. One of these is the acute reduction in sensitivity to painful stimuli, called exercise-induced hypoalgesia (EIH). This phenomenon has been studied since 1979 and has shown improvements in pain thresholds with both aerobic and resistance training in healthy, pain-free populations and different chronic pain conditions. Although there has been extensive research on EIH in healthy populations and those with chronic musculoskeletal pain, surprisingly little attention has been given to individuals with neurological pathologies. Chronic pain is found in more than 50% of patients after stroke, and 70% of affected individuals experience pain on daily activities. Reported prevalences of post-stroke pain (PSP) between different studies, but there is a general consensus that it is an underreported phenomenon. Patients with pain experience greater cognitive and functional decline, fatigue, depression and lower quality of life. Multiple factors contribute to PSP, and various approaches exist to treat all the variables influencing it. This study aims to compare the effects of exercise on pain perception in healthy individuals and stroke patients without pain, using the same cardiovascular training protocol, to better understand the mechanisms of EIH and its maintenance after stroke, ultimately aiming to improve the treatment of people with stroke.