To exercise or not to exercise in chronic fatigue syndrome?

To the Editor: A recent editorial1 and article2 continue to promulgate and link the unproven concepts that patients with chronic fatigue syndrome (CFS) are “deconditioned” and exercise is beneficial in treatment. The cited study by Fulcher and White3 is open to opposite conclusions, depending on their use of the outcome descriptor “better”. If the term is restricted to “much better” and “very much better”, then, as cited by Lloyd,1 16 of 29 people with CFS rated themselves as “better” after a graded exercise program, compared with only 8 of 30 in the control group who completed a flexibility treatment regimen. However, if the “better” descriptor combines “a little better”, “much better” and “very much better”, which is the interpretation used by Wallman et al,2 then the scores for the exercise versus flexibility groups are not different, being 27 of 29 and 26 of 30, respectively, agreeing with the conclusion of Wallman et al.2

Whichever interpretation is applied, any beneficial effect of the graded exercise program in people with CFS in these studies must be independent of any training effect or change in level of “conditioning”, as this was reported in one study,2 but not in the other.3

A fundamental flaw with most exercise studies in CFS is the use of submaximal or symptom-limited tests, which provide notoriously misleading data when compared with maximal exercise testing procedures.4,5 Wallman et al2 correctly identify maximal oxygen consumption as the “gold standard” measure of exercise capacity, yet such measurements were not made in the three articles they cited. When such procedures are applied, the exercise capacity of people with CFS is not significantly different from either measured or age-predicted values for healthy sedentary people.6 Wallman et al2 suggested that maximal testing procedures could favour the recruitment of “more robust or healthier” patients and provide misleading information. In the first place this is denied by the study of Sargent et al,6 in which the illness status reported by patients who completed the maximal tests was similar to that in previous CFS studies. In the second place, the maximal test protocol chosen for a given population should be designed to exclude any influence of fatigue on the metabolic measurements. This is confirmed by the results from the study cited,6 in which the metabolic measurements met the published criteria of a maximal test.4,5

In summary, patients with CFS are not “deconditioned”. Neither their muscle strength nor their exercise capacity is different from that of other sedentary members of the community (> 70%). We remain unaware of any incontrovertible evidence that the various “exercise training” programs suggested in previous articles improve either the physiological or clinical status of people with CFS.