Chronic fatigue syndrome, deconditioning, and graded exercise therapy.

Abstract

Dear Editor-in-Chief: Sargent et al. reported a case-control study of physiological responses to exercise in patients with chronic fatigue syndrome (CFS) (10). We believe that they wrongly concluded that “exercise capacity of CFS patients is not significantly impaired,. . .”; “neither physical deconditioning nor cardiorespiratory dysfunctioning is a critical factor in the fatigue”; and “. . .exercise training programs for CFS patients. . .” may be based on a false premise of “. . .correcting the effects of deconditioning” (10). Sargent et al. concluded that exercise capacity was “not significantly impaired” but did not provide the data. Five case-control studies have found that exercise capacity was significantly reduced in CFS subjects (2,4,6,9,11). A sixth study found a 7% trend for this (1). A small study found nearly a 2-min difference in an exercise test, with no statistical significance (7). An eighth study also concluded that exercise capacity was reduced, although time spent exercising was not given (8). Six of these studies also found that patients with CFS were either more deconditioned than healthy controls or at least as deconditioned as sedentary healthy controls (2,4,6,7,9,11). Only one study found no significant differences from healthy controls, although both patients and controls were less fit than predicted (1). This is the only other study to conclude that deconditioning does not help to maintain CFS (1). However, CFS subjects had significant and negative correlations between fitness and both fatigue and functional impairment and a positive correlation with physical activity (1), suggesting the opposite interpretation. These studies required an exercise test, which meant that the most disabled patients (most likely to be deconditioned) were excluded. Sargent et al. criticized some of these studies for not stratifying by gender (10), but these studies matched gender by group or pairs against healthy controls instead, including the studies that Sargent et al. suggested did not do so (4,6). Regarding the role of deconditioning, exercise incapacity was significantly correlated with reduced muscle strength and higher heart-rate response to submaximal exercise in CFS patients (6). The latter may be related to reduced left ventricular mass found in CFS (3). A graded exercise program produced a 13% increase in peak V̇O2 and a 26% increase in quadriceps muscle strength in the same patients (5,6). Improved exercise capacity was correlated with reduced heart-rate response to submaximal exercise (6). These data contradict the Sargent et al. view that there is “no published evidence of physiological improvement with exercise training program recommended in the treatment of CFS” (10). Two systematic reviews of the management of CFS concluded that graded exercise therapy had “positive results” in three studies of high quality (12). Graded exercise programs, designed to reverse deconditioning, are safe and effective treatments in patients with CFS (5,12). These programs were not “imposed” as stated by Sargent et al. (10); nor should they be. It would be a great pity if patients were denied the chance of improvement because of wrong interpretations of the literature. Peter D. White, MD, FRCP, FRCPsych Kathy Y. Fulcher, PhD