J Transl Med. 2014 Jan 23;12(1):20. [Epub ahead of print]
Decreased oxygen extraction during cardiopulmonary exercise test in
patients with chronic fatigue syndrome.
Vermeulen RC, Vermeulen van Eck IW.
BACKGROUND: The insufficient metabolic adaptation to exercise in
Chronic Fatigue Syndrome (CFS) is still being debated and poorly
METHODS: We analysed the cardiopulmonary exercise tests of CFS
patients, idiopathic chronic fatigue (CFI) patients and healthy
visitors. Continuous non-invasive measurement of the cardiac output by
Nexfin(R) (BMEYE B.V. Amsterdam, the Netherlands) was added to the
cardiopulmonary exercise tests. The peak oxygen extraction by muscle
cells and the increase of cardiac output relative to the increase of
oxygen uptake (DeltaQ'/DeltaV'O2) were measured, calculated from the
cardiac output and the oxygen uptake during incremental exercise.
RESULTS: The peak oxygen extraction by muscle cells was 10.83 +/- 2.80
ml/100ml in 178 CFS women, 11.62 +/- 2.90 ml/100ml in 172 CFI, and
13.45 +/- 2.72 ml/100ml in 11 healthy women (ANOVA: P=0.001), 13.66
+/- 3.31ml/100ml in 25 CFS men, 14.63 +/- 4.38 ml/100ml in 51 CFI, and
19.52 +/- 6.53 ml/100ml in 7 healthy men (ANOVA: P=0.008).The
DeltaQ'/DeltaV'O2 was > 6 L/L (normal DeltaQ'/DeltaV'O2 [almost equal
to] 5 L/L) in 70% of the patients and in 22% of the healthy group.
CONCLUSION: Low oxygen uptake by muscle cells causes exercise
intolerance in a majority of CFS patients, indicating insufficient
metabolic adaptation to incremental exercise. The high increase of the
cardiac output relative to the increase of oxygen uptake argues
against deconditioning as a cause for physical impairment in these
PMID: 24456560 [PubMed - as supplied by publisher]