Discriminative Validity of Metabolic and Workload Measurements for Identifying People With Chronic Fatigue Syndrome

Abstract

The lack of any significant differences between groups for the first exercise test would appear to support a deconditioning hypothesis for CFS symptoms. However, the results from the second test indicated the presence of CFS-related postexertion fatigue. It might be concluded that a single exercise test is insufficient to reliably demonstrate functional impairment in people with CFS. A second test might be necessary to document the atypical recovery response and protracted fatigue possibly unique to CFS, which can severely limit productivity in the home and workplace.

Metabolic profiling indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy/chronic fatigue syndrome

“…Our data, suggesting that ME/CFS is associated with impaired efficiency of energy metabolism combined with lactate overproduction, may explain why many ME/CFS patients reach anaerobic threshold at a low workload (9)(10)(11). This is supported by an individual patient report (35) and our own observations of patients with severe ME/CFS that had lactate levels elevated to more than 8 mM from just standing upright for 10 minutes.…”

Chronic fatigue syndrome – an update

“…54 A recent study investigated functional capacity and post-exertion fatigue in 51 CFS patients and 10 healthy controls during two cardiopulmonary exercise tests with a 24-h interval. 55 All participants reached their peak workload, but in the CFS group, peak workload was significantly lower than in the control group (p = 0.005). The CFS patients were unable to reproduce their performance of the first test during the second test, in contrast to the control group.…”

“…55 Strikingly, CFS patients were unable to reproduce their initial performance 24 h later, while healthy controls did manage to do so. Whether this is due to deconditioning or other underlying factors needs to be further investigated.…”

An Accurate Diagnosis of Myalgic Encephalomyelitis and Chronic Fatigue Syndrome requires strict Clinical Case definitions and Objective Test Methods

“…It is very unlikely that all patients meeting specific diagnostic criteria will show abnormal results for all specific objective tests, e.g. repeated exercise tests [41,42], cognitive tests [43,44], tilt table tests [45,46], muscle power (endurance) tests [47,48], but it is essential to establish physiological and neurocognitive abnormalities in the individual patients impartially, both in clinical practice as in research studies.…”

“…repeated exercise tests [41,42], cognitive tests [43,44], tilt table tests [45,46], muscle power (endurance) tests [47,48], for diagnosing patients [49] and determining the effect of interventions [50], to find correlations between symptoms/subjective measures and objective test outcomes, and to define symptomatic subgroups of the ME and CFS patient population [51].…”