Cardiopulmonary Exercise Test (CPET) Methodology for Assessing Exertion Intolerance in ME/CFS (Stevens et al., 2018)

Pyrrhus

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I don't think this paper has been posted yet, but it's a good review of the studies that look at CardioPulmonary Exercise Tests (CPET) to document PEM/exertion intolerance in ME.


Cardiopulmonary Exercise Test Methodology for Assessing Exertion Intolerance in ME/CFS (Stevens et al., 2018)
https://www.frontiersin.org/articles/10.3389/fped.2018.00242/full

For those unfamiliar with 2-day CPET testing in ME:
A patient is asked to perform an exertion test two days in a row. Whereas healthy people can repeat their exertion performance from the first day on the second day, people with ME can not, as they perform much more poorly on the second day than they did on the first day. This 2-day CPET test result is an objective measurement that has been widely used as a proxy for Post-Exertional Malaise (PEM), even though PEM encompasses much more than just the inability to repeat exertion performance.

But don't confuse Exertion Intolerance with Exercise Intolerance:
Exercise Intolerance vs. PEM/Exertion Intolerance
https://forums.phoenixrising.me/threads/exercise-intolerance-vs-pem-exertion-intolerance.86876/


Excerpt:
Stevens et al 2018 said:
Background:
Concise methodological directions for administration of serial cardiopulmonary exercise testing (CPET) are needed for testing of patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Maximal CPET is used to evaluate the coordinated metabolic, muscular, respiratory and cardiac contributions to energy production in patients with ME/CFS. In this patient population, CPET also elicits a robust post-exertional symptom flare (termed, post-exertional malaise); a cardinal symptom of the disease. CPET measures are highly reliable and reproducible in both healthy and diseased populations. However, evidence to date indicates that ME/CFS patients are uniquely unable to reproduce CPET measures during a second test, despite giving maximal effort during both tests, due to the effects of PEM on energy production.

Methodology:
To document and assess functional impairment due to the effects of post-exertional malaise in ME/CFS, a 2-day CPET procedure (2-day CPET) has been used to first measure baseline functional capacity (CPET1) and provoke post-exertional malaise, then assess changes in CPET variables 24 h later with a second CPET to assess the effects of post-exertional malaise on functional capacity. The second CPET measures changes in energy production and physiological function, objectively documenting the effects of post-exertional malaise. Use of CPET as a standardized stressor to induce post-exertional malaise and quantify impairment associated with post-exertional malaise has been employed to examine ME/CFS pathology in several studies. This article discusses the results of those studies, as well as the standardized techniques and procedures for use of the 2-day CPET in ME/CFS patients, and potentially other fatiguing illnesses.

Conclusions:
Basic concepts of CPET are summarized, and special considerations for performing CPET on ME/CFS patients are detailed to ensure a valid outcome. The 2-day CPET methodology is outlined, and the utility of the procedure is discussed for assessment of functional capacity and exertion intolerance in ME/CFS.
 
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Pyrrhus

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Related discussions:


Patients with chronic fatigue syndrome performed worse than controls in a controlled repeated exercise study despite a normal oxidative phosphorylation capacity (Vermeulen et al., 2010)
https://forums.phoenixrising.me/thr...rmal-oxidative-phosphorylation-capacity.6858/
A paper that confirmed the 2007 finding of an inability to repeat exercise performance on day 2 of the CPET, but suggests that the problem is not due to faulty mitochondria.


Chronotropic Intolerance: An Overlooked Determinant of Symptoms and Activity Limitation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome? (Davenport et al., 2019)
https://forums.phoenixrising.me/thr...symptoms-and-activity-limitation-in-me.75663/
A paper that suggests the reason for the inability to repeat exercise performance on day 2 of the CPET may be due to dysautonomia, specifically chronotropic intolerance.


Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome. (Lien et al., 2019)
https://forums.phoenixrising.me/thr...ng-repeated-exercise-testing-in-me-cfs.76541/
A paper that shows that ME patients generate lactic acid during exercise earlier, at lower intensities, than healthy controls do. This is consistent with previous findings of a reduced "anaerobic threshold" in ME patients.
 

SnappingTurtle

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I appreciate your postings on this, @Pyrrhus . This test confirmed I suffer from PEM and provides objective evidence of my disability. It gave me the confirmation that I desperately needed at a time when my local doctors simply shrugged their shoulders in defeat or worse, turned their backs on me because I was proving too challenging a case. It gave me something tangible to show my family that it is NOT something made-up. It is real and debilitating.

Thanks to the information on this forum and in How To Get On https://howtogeton.wordpress.com/, I was well aware that to subject myself to the 2 day CPET meant I would induce PEM. I weighed the risks but ultimately decided it was worth it, and proceeded with the intention of devoting the next month to full bed rest. At any rate, if my ME specialist felt I was too ill to do it, he would have discouraged the test. He was there to monitor me and my vitals the entire time.

With the information from the 2 day cpet, I have solid stats on my Anaerobic threshold and how quickly I can hit it. I use this to help me pace myself: with my fitness tracker and smaetphone app, an alarm sounds when I need to slow down.
 

Pyrrhus

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And for comparison with studies that use a two-day CPET to look at PEM/exertion intolerance, here is a paper that used a one-day invasive CPET to investigate exercise intolerance in ME, and found that the exercise intolerance is actually due to dysautonomia of the nerves that control constriction of veins - while saying nothing about PEM/exertion intolerance:

Insights from Invasive Cardiopulmonary Exercise Testing of Patients with ME/CFS (Joseph et al., 2021)
https://forums.phoenixrising.me/thr...patients-with-me-cfs-joseph-et-al-2021.82907/