Clinical Knowledge and Reasoning Informed by Cardiopulmonary Exercise Testing to Guide Physical Activity and Management of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) encompasses seemingly varied and disparate symptoms, making the diagnosis challenging and arduous. The hallmark symptom of post exertional malaise, sometimes considered a disease within itself, erodes the pre-illness lifestyle to a very low tolerance for exertion and consequently, a substantially lower level of physical activity. However, many with ME/CFS, particularly early in the diagnosis, routinely exceed the new, lower tolerance for daily activities and further worsen the post exertional malaise response and health status. Identifying post exertional malaise requires a temporal assessment of symptom onset or exacerbation and the resultant impact on functional activities. Objective data from sequential cardiopulmonary exercise tests over two days (2-d CPET) has documented the deleterious effects of post exertional malaise and decline in exertion tolerance, oxygen consumption, and energy production in ME/CFS compared to healthy controls. These consistent CPET findings are further enriched by additional measures routinely obtained during CPET that point to mechanistic failures in energy metabolism. Additional insight and guidance for treatment and management of ME/CFS may lie in a deeper examination of routine CPET variables that consistently support dysfunction of key aspects of autonomic regulation. Understanding what we learn from a 2-d CPET is essential to providing safe guidance for physical activity and medical management of one with ME/CFS.