To exercise or not to exercise in chronic fatigue syndrome?

In reply: Scroop and Burnet correctly identify the vagaries of the necessarily subjective measurement of outcomes in intervention studies of chronic fatigue syndrome (CFS). Given that muscle strength, endurance and recovery are essentially normal in patients with CFS,1 rather than become too focused on the best approach to measurement of exercise capacity the key issue is whether patients benefit in terms of self-reported symptom severity or functional status.

The weight of evidence indicates that graded physical exercise does provide such benefits. Whether this occurs via improvements in aerobic fitness or via the well-recognised psychological and social benefits of exercise is something of a side-issue.

Stein and Hunter draw attention to the recently published Canadian consensus guidelines for the diagnosis and management of myalgic encephalomyelitis/CFS. Although this document may provide a welcome recognition for Canadian patients with the disorder, unlike the Australian guidelines,2 it is devoid of an evidence base for the recommendations. Sadly, rather than “add[ing] clinical specificity”, it is also highly likely that the modified diagnostic criteria fall into the trap of preferentially identifying patients with somatisation disorder,3 as such individuals often report large numbers of unexplained symptoms, and hence the addition of 20 or more symptoms to the diagnostic criteria may well bias towards inclusion of such patients.

Stein and Hunter are incorrect in the assertion that SPHERE was designed for psychiatric screening in primary care, as the instrument arose out of our studies in CFS specifically seeking to identify clinically significant fatigue states.4

I support the recommendation about caution in generalising from existing published data regarding graded exercise to patients who are severely ill, as such patients are indeed likely to be under-represented in published studies. Nevertheless, it is noteworthy that the recommendations made in the Canadian document cited by Stein and Hunter also clearly support the notion of graded physical exercise: “Patients should gently and gradually increase their level of activity.” Thus, rather than leave the severely affected to continue to “barely venture outside their homes”, I would recommend a carefully designed graded exercise program in the home, with a goal of improving functional performance sufficiently to escape those confines.