Dear Sir,
As in the past [1], the effects of exercise in the treatment of chronic fatigue syndrome (CFS) are conflicting. Indeed, while Powell et al. [2], in 2004, reported that graded exercise was beneficial to CFS patients, Black et al. [3] have lately written that ‘overall mood, muscle pain intensity, and time spent each day with fatigue worsened following increased activity’ [3] in CFS patients, despite the fact that their increase in daily physical activity was rather moderate (28%) [3]. The virtually opposite effects of exercise in different groups of CFS patients [1–3] may reflect their different cortisol levels [1], which, just as occurred some years ago [1], continue to be contradictory. For example, Inder et al. [4], in March 2005, reported that cortisol levels were normal in their patients with CFS, whereas Segal et al. [5], in the same month, reported that their subjects with CFS had hypocortisolism.
Considering that most features of CFS, such as ‘debilitating fatigue, an abrupt onset precipitated by a stressor, feverishness, arthralgias, myalgias, adenopathy, postexertional fatigue, exacerbation of allergic responses, and disturbances in mood and sleep are all characteristic of glucocorticoid insufficiency’ [6], it is not surprising that hypocortisolism has been convincingly shown to be implicated in the pathophysiology of CFS [7]. Therefore, especially the postexertional fatigue caused by glucocorticoid insufficiency [6] strongly suggests that exercise could be of benefit to CFS patients with high [1] or normal cortisol levels [4], whereas it could be harmful to CFS patients with hypocortisolism [1, 5, 6]. Unfortunately, because of the misleading coexistence of quite different diagnostic criteria for CFS [1], it is difficult to predict the patients with CFS who are more likely to have hypocortisolism and which would worsen with exercise. However, it is arguable that the presence or absence of lymphadenopathy [8], which is a sign of hypocortisolism [6, 9] and is one of the 43 clinical features that CFS shares with Addison’s disease [10–12], could reliably discriminate CFS patients who may worsen with exercise from those who may improve with it. Indeed, lymphadenopathy, unlike other symptoms of CFS [11, 12], many of which are non-specific and can also be found in depression and other affective disorders [11, 12], is far from being common in physical diseases and is absent in psychiatric conditions.
You can read the rest of this comment here: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2005.01526.x/full
Source: Baschetti R. Chronic fatigue syndrome, exercise, cortisol and lymphadenopathy. J Intern Med. 2005 Sep;258(3):291-2. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2005.01526.x/full (Full article)