Preprint Inefficient energy consumption is related to post exertional malaise during cardiopulmonary exercise testing in long COVID, 2025, Tamariz

[Dolphin]

Inefficient energy consumption is related to post exertional malaise during cardiopulmonary exercise testing in long COVID

BackgroundDyspnea, fatigue and post-exertional malaise (PEM) are hallmark features of long Covid and emerging evidence suggests that abnormal energy metabolism may contribute to these symptoms. A cardiopulmonary exercise test (CPET) provides a detailed physiologic assessment of ventil...

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Research Article

Inefficient energy consumption is related to post exertional malaise during cardiopulmonary exercise testing in long COVID​

Leonardo Tamariz1
Brian Garnet1
Santiago Avecillas1
Elizabeth Bast1
Jeff Cournoyer2
Nicole DeLuca1
Nancy Klimas2
Ana Palacio1
1Miami VA Healthcare System,

2Nova Southeastern University

This is a preprint; it has not been peer reviewed by a journal.

Inefficient energy consumption is related to post exertional malaise during cardiopulmonary exercise testing in long COVID

BackgroundDyspnea, fatigue and post-exertional malaise (PEM) are hallmark features of long Covid and emerging evidence suggests that abnormal energy metabolism may contribute to these symptoms. A cardiopulmonary exercise test (CPET) provides a detailed physiologic assessment of ventil...

doi.org

This work is licensed under a CC BY 4.0 License

Abstract​

Background​

Dyspnea, fatigue and post-exertional malaise (PEM) are hallmark features of long Covid and emerging evidence suggests that abnormal energy metabolism may contribute to these symptoms. A cardiopulmonary exercise test (CPET) provides a detailed physiologic assessment of ventilatory and cardiovascular function and can offer insights into metabolic substrate utilization energy at rest and during exertion. Our aim was to evaluate patterns of energy metabolism at rest and during exercise during a CPET in patients with long Covid.

Methods​

We conducted a cross-sectional study of consecutive non-selected patients that had been referred for a CPET. We included two groups: a long COVID and a control group. The CPET was performed on a cycle ergometer and we measured standard variables including oxygen uptake (V̇O₂), respiratory exchange ratio (RER), breathing reserve, heart rate, O2 pulse, and anaerobic threshold. We used RER to calculate indirect calorimetry estimating the use of carbohydrates and fat at rest and exertion. We analyzed the association between long COVID symptom severity symptoms including fatigue and post-exertional malaise (PEM) with patterns of energy consumption. We used logistic regression and area under the receiver operating characteristic curve to determine which CPET variables were most associated with long COVID.

Results​

CPET results were analyzed for 50 patients who met the definition of long COVID and 45 patients controls. Long COVID patients and controls had similar peak V̇O₂, heart rate on exertion and V̇O₂ at anaerobic threshold. Seventy-three percent of patients with long COVID had predominant energy use of carbohydrates rather than fat at rest compared to 20% of controls. In multivariable models the odds ratio of using fat as energy source at rest was 0.99; 95% CI 0.99–0.99; p = 0.04. Patients with long COVID and severe fatigue as well as severe PEM had higher usage of carbohydrates (p < 0.01) and similar use of fat.

Conclusion​

Patients with long COVID use energy inefficiently and this pattern could serve as a diagnostic feature in certain presentations of long COVID.

 

[Snow Leopard]

I'm not convinced using carbohydrates rather than fat is "inefficient".
This is another study that the authors don't understand why they should do a 2-day CPET and what they are supposed to be looking for.

 

[Utsikt]

It seems like figure 2-4 are missing.

This is how they measured PEM:

We also used the C19-YRSm answers for fatigue and post-exertional malaise and classified them as mild, moderate and severe. We defined fatigue and PEM as having at least mild fatigue or PEM in the C19-YRSm

This question:

Crashing or relapse hours or days after physical, cognitive or emotional exertion

https://c19-yrs.com/wp-content/uploads/2024/07/Modified-C19YRS-Self-Report.pdf

This is their conclusion:

In conclusion our study demonstrates evidence that indirect calorimetry showing carbohydrate metabolism at rest may support the diagnosis of LC and may be reflective of the pathophysiology of chronic fatigue and PEM in these patients. Future studies should explore how different rehabilitation strategies improve energy use and production at rest, modify the metabolic and inflammatory response to exercise, and alter the risk of ongoing PEM in prospective studies.

Of course their instinct is to talk about rehab..

 

[rvallee]

Future studies should explore how different rehabilitation strategies improve energy use and production at rest, modify the metabolic and inflammatory response to exercise

I don't think that's a thing. What's up with the infinite imaginary speculation about finding the perfect kind of rehab, not too hot, not too cold, just perfect? It doesn't even make sense, why would that even produce benefits? "Imagine a world"-based Goldilocks medicine yet again, where the standards are, somehow, even lower than in other forms of alternative medicine.