Is Swimming a More Tolerable Form of Movement for Individuals With Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome?

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating multisystem disorder characterized by extreme fatigue, sleep dysfunction, pain, and post-exertional malaise and/or post-exertional fatigue, and is accompanied by orthostatic intolerance, and neuroendocrine and immune manifestations. The defining feature of ME/CFS is the delayed onset (\~12-48 h) exacerbation of symptoms following physical, cognitive, orthostatic, and even emotional exertion, termed post-exertional malaise (PEM). As such, despite the known benefits of exercise for improving function in most disease states including other multisystem inflammatory disorders like sepsis, exercising with ME/CFS is generally contraindicated to avoid a worsening of the condition. It has been demonstrated that neurovascular dysregulation underlies much of the exercise intolerance in ME/CFS. When neurovascular function is normalized with pharmacologic cholinergic stimulation in ME/CFS patients performing upright cycling exercise, cardiac output, right atrial pressures, and maximal oxygen consumption are improved, possibly preventing post-exertional malaise. Water immersion can also be used to normalize cardiac output and right atrial pressures, as the prone/supine postures and hydrostatic pressure of the water act to passively encourage venous return. Furthermore, the human dive reflex (when the face is submerged in cool water) increases parasympathetic activation to the heart, slowing down heart rate. There is also evidence of anti-inflammatory effects of swimming in patients with cardiovascular, neurological, and rheumatological diseases, which could also improve inflammation in ME/CFS patients. The purpose of this study is to determine whether light-to-moderate swimming may be a more tolerable form of movement for individuals with ME/CFS.