The influence of aerobic fitness and fibromyalgia on cardiorespiratory and perceptual responses to exercise in patients with chronic fatigue syndrome.

OBJECTIVE: To investigate cardiorespiratory and perceptual responses to exercise in patients with chronic fatigue syndrome (CFS), accounting for comorbid fibromyalgia (FM) and controlling for aerobic fitness. METHODS: Twenty-nine patients with CFS only, 23 patients with CFS plus FM, and 32 controls completed an incremental bicycle test to exhaustion. Cardiorespiratory and perceptual responses were measured. Results were determined for the entire sample and for 18 subjects from each group matched for peak oxygen consumption. RESULTS: In the overall sample, there were no significant differences in cardiorespiratory parameters between the CFS only group and the controls. However, the CFS plus FM group exhibited lower ventilation, lower end-tidal CO2, and higher ventilatory equivalent of carbon dioxide compared with controls, and slower increases in heart rate compared with both patients with CFS only and controls. Peak oxygen consumption, ventilation, and workload were lower in the CFS plus FM group. Subjects in both the CFS only group and the CFS plus FM group rated exercise as more effortful than did controls. Patients with CFS plus FM rated exercise as significantly more painful than did patients with CFS only or controls. In the subgroups matched for aerobic fitness, there were no significant differences among the groups for any measured cardiorespiratory response, but perceptual differences in the CFS plus FM group remained. CONCLUSION: With matching for aerobic fitness, cardiorespiratory responses to exercise in patients with CFS only and CFS plus FM are not different from those in sedentary healthy subjects. While CFS patients with comorbid FM perceive exercise as more effortful and painful than do controls, those with CFS alone do not. These results suggest that aerobic fitness and a concurrent diagnosis of FM are likely explanations for currently conflicting data and challenge ideas implicating metabolic disease in the pathogenesis of CFS.

Exercise and cognitive performance in chronic fatigue syndrome.

PURPOSE: To determine the effect of submaximal steady-state exercise on cognitive performance in patients with chronic fatigue syndrome (CFS) alone, CFS with comorbid fibromyalgia FM (CFS + FM), and sedentary healthy controls (CON). METHODS: Twenty CFS-only patients, 19 CFS + FM, and 26 CON completed a battery of cognitive tests designed to assess speed of information processing, variability, and efficiency. Tests were performed at baseline, immediately before, and twice following 25 min of either cycle ergometry set at 40% of peak oxygen capacity or quiet rest. RESULTS: There were no group differences in average percentage of peak oxygen consumption during exercise (CFS = 45%; CFS + FM = 47%; Control = 43%: P = 0.2). There were no significant effects of acute exercise on cognitive performance for any group. At baseline, one-way ANOVA indicated that CFS patients displayed deficits in speed of processing, performance variability, and task efficiency during several cognitive tests compared with healthy controls. However, the CFS + FM patients were not different than controls. Repeated measures ANOVA indicated that across all tests (pre- and postexercise) CFS, but not CFS + FM, were significantly less consistent (F2,59 = 3.7, P = 0.03) and less efficient (F2,59 = 4.6, P = 0.01) than controls. CONCLUSION: CFS patients without comorbid FM exhibit subtle cognitive deficits in terms of speed, consistency, and efficiency that are not improved or exacerbated by light exercise. Importantly, our data suggest that CFS + FM patients do not exhibit cognitive deficits either pre- or postexercise. These results highlight the importance of disease heterogeneity in studies determining acute exercise and cognitive function in CFS.

Fatigue in the elderly population.

Fatigue in the elderly population is a complex phenomenon. Although a number of factors contributing to the fatigue have been identified, its basic mechanism remains elusive. Additional research on prevalence, identification, diagnosis, severity of fatigue, and associated factors and the role of exercise as an effective treatment modality could lead to a better understanding of the causal factors.