18.6: Exercise and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

18.6.1. Definition and Description

Exercise has been described as medicine for more than 26 chronic diseases (Pedersen & Saltin, 2015) but can exercise really be considered medicine for everyone with a chronic illness? This section will explore how people with a condition called myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS) can be affected by even mild levels of exertion. ME/CFS is a complex, debilitating, and long-term illness characterized by chronic fatigue, a substantial reduction in the ability to do usual activities, and other symptoms such as cognitive dysfunction and sleep abnormalities. ME/CFS has been a topic of much debate and controversy, and historically, patients have felt marginalized and have had to struggle to have the legitimacy of ME/CFS recognized (Blease et al., 2017). Many people with ME/CFS have not been diagnosed, partly due to the lack of laboratory or diagnostic tests and a lack of education for healthcare professionals about the condition. People with ME/CFS can struggle to keep a job, go to school or fully participate in their family and social life. One of the main characteristics of ME/CFS is post-exertional malaise, a worsening of symptoms after a physical or mental activity that would not have caused a problem before the illness (Centers for Disease Control and Prevention, 2018). There has been difficulty in defining and measuring post-exertional malaise (Chu et al., 2018; Holtzman et al., 2019), but it can involve exhaustion, cognitive difficulties, and muscle/joint pain that can peak between 24-72 hours after the exertion (Chu et al., 2018; Holtzman et al., 2019). Post-exertional malaise can be unpredictable, disruptive to everyday life (often requiring complete bed rest with little sensory input), and can have a significant impact on emotional well-being (Stussman et al., 2020). Considering this issue of post-exertional malaise, it becomes easier to see that for a minority of people, a blanket recommendation for exercise has the potential to be harmful.

18.6.2. Is Exercise Therapeutic for People with ME/CFS?

The 2011 PACE trial, published in The Lancet (a world-leading, prestigious medical journal), involved a comparison of graded exercise therapy and cognitive behavioural therapy for people with ME/CFS (see White et al., 2011, 2013). The investigators concluded both therapies were moderately effective for ME/CFS and led to "recovery" in over 20% of participants. However, there were several serious criticisms of the trial, including methodological concerns such as outcome switching. This means that during the trial, the researchers lowered their original threshold for recovery (i.e., switched a study outcome), resulting in more participants meeting the criteria for recovery. In general, improvements in self-report measures were not reflected in markers of functional recovery (e.g., the number of days lost from work). Another area of controversy was that the interventions were based on a cognitive behavioural model of ME/CFS, which proposed that rather than ongoing disease processes, ME/CFS is maintained and perpetuated by dysfunctional cognitions and avoidance of activity (see (Geraghty et al., 2019b)). Patients with ME/CFS can benefit from psychological support to help cope with the condition but reject the implication that the disease can be reversed by overcoming illness beliefs (Wilshire et al., 2018). This model is disputed because it suggests that there is no ongoing biological basis for the disease, despite growing evidence to the contrary.

Most patients do not think that graded exercise therapy is appropriate for their needs, and people with more severe ME/CFS report that exercise can have a negative impact (Geraghty et al., 2019a). Because the results of the PACE trial conflicted with a patient's experience of managing their condition, and due to the previously mentioned methodological issues, the researchers were challenged to release the study data for reanalysis by independent scientists. Eventually, the controversy culminated in a UK court tribunal, where the researchers were ordered to share their data. A reanalysis of the data found that if the researchers had used their original criteria for recovery, only 4% of patients who received graded exercise therapy would have met the threshold, compared to 3% of patients who received standard medical care (Wilshire et al., 2018). This is an interesting case to consider because this published research not only distorted the scientific record (i.e. indicated that graded exercise therapy was more beneficial than is likely the case) but was so influential that it directly affected standard treatment recommendations for people with ME/CFS. Some organizations have now removed these recommendations from their guidance for people with ME/CFS, and an updated Cochrane systematic review is underway due to the limited applicability of previous reviews (Larun et al., 2019). Currently, increases in activity are only advised if patients feel they are coping with current activity levels (Bested & Marshall, 2015). Any program involving exercise must be tailored to the individual, with awareness and understanding that worsening of symptoms is possible, and symptoms must be monitored over several days (not only immediately after exercise).