Countrygirl
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I couldn't find this posted elsewhere, and apologies if I have missed it
http://www.translational-medicine.com/content/pdf/1479-5876-12-104.pdf
Published 23rd April 2014
Journal of Translational Medicine 2014, 12:104 doi:10.1186/1479-5876-12-104
Betsy A Keller (keller@ithaca.edu)
John Luke Pryor (luke.pryor@uconn.edu)
Ludovic Giloteaux (ludovicgiloteaux@gmail.com)
http://www.translational-medicine.com/content/pdf/1479-5876-12-104.pdf
Published 23rd April 2014
Journal of Translational Medicine 2014, 12:104 doi:10.1186/1479-5876-12-104
Betsy A Keller (keller@ithaca.edu)
John Luke Pryor (luke.pryor@uconn.edu)
Ludovic Giloteaux (ludovicgiloteaux@gmail.com)
Inability of myalgic encephalomyelitis / chronic
fatigue syndrome patients to reproduce VO2peak
indicates functional impairment
Abstract
Background
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multi-system illness
characterized, in part, by increased fatigue following minimal exertion, cognitive impairment,
poor recovery to physical and other stressors, in addition to other symptoms. Unlike healthy
subjects and other diseased populations who reproduce objective physiological measures
during repeat cardiopulmonary exercise tests (CPETs), ME/CFS patients have been reported
to fail to reproduce results in a second CPET performed one day after an initial CPET. If
confirmed, a disparity between a first and second CPET could serve to identify individuals
with ME/CFS, would be able to document their extent of disability, and could also provide a
physiological basis for prescribing physical activity as well as a metric of functional
impairment.
Methods
22 subjects diagnosed with ME/CFS completed two repeat CPETs separated by 24 h.
Measures of oxygen consumption (VO2), heart rate (HR), minute ventilation (Ve), workload
(Work), and respiratory exchange ratio (RER) were made at maximal (peak) and ventilatory
threshold (VT) intensities. Data were analyzed using ANOVA and Wilcoxon’s Signed-Rank
Test (for RER).
Results
ME/CFS patients showed significant decreases from CPET1 to CPET2 in VO2peak (13.8%),
HRpeak (9 bpm), Ve peak (14.7%), and Work@peak (12.5%). Decreases in VT measures
included VO2@VT (15.8%), Ve@VT (7.4%), and Work@VT (21.3%). Peak RER was high
(≥1.1) and did not differ between tests, indicating maximum effort by participants during
both CPETs. If data from only a single CPET test is used, a standard classification of
functional impairment based on VO2peak or VO2@VT results in over-estimation of
functional ability for 50% of ME/CFS participants in this study.
Conclusion
ME/CFS participants were unable to reproduce most physiological measures at both maximal
and ventilatory threshold intensities during a CPET performed 24 hours after a prior maximal
exercise test. Our work confirms that repeated CPETs warrant consideration as a clinical
indicator for diagnosing ME/CFS. Furthermore, if based on only one CPET, functional
impairment classification will be mis-identified in many ME/CFS participants.