Utsikt
Senior Member (Voting Rights)
So what Davenport et al say might be anaerobic metabolic abnormalities in pwME/CFS might still be normal anaerobic metabolism for very inactive people?
ME/CFS and Long COVID Demonstrate Similar Bioenergetic Impairment and Recovery Failure on Two-Day Cardiopulmonary Exercise Testing, 2026, Davenport+
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DMissa
Senior Member (Voting Rights)
This would depend on whether differences in activity levels between the cohorts are sufficient to elicit an effect on this in muscle.
Eddie
Senior Member (Voting Rights)
I wanted to have another look at this paper in light of the recent CPET study that reported no difference.
The point of the 2 day CPET is to show a difference between the Vo2 and workload on day 2 of the test. That decrease is meant to represent the impact of PEM.
However, this paper does not address the change in CPET results between the days at all as far as I can see. The paper focuses on the differences in Vo2 and workload, but not on the differences in the changes between test 1 and 2. I feel like I have to be missing something because that makes the results completely uninteresting... The vast majority of the significant differences between healthy controls and pwME in test 2 were also present in test 1. So all this shows is that the controls were somewhat fitter than pwME, which is not surprising and is just a reflection of poor control selection. I honestly can't understand why they wouldn't have commented on the differences between the responses to the CPETs.
The point of the 2 day CPET is to show a difference between the Vo2 and workload on day 2 of the test. That decrease is meant to represent the impact of PEM.
However, this paper does not address the change in CPET results between the days at all as far as I can see. The paper focuses on the differences in Vo2 and workload, but not on the differences in the changes between test 1 and 2. I feel like I have to be missing something because that makes the results completely uninteresting... The vast majority of the significant differences between healthy controls and pwME in test 2 were also present in test 1. So all this shows is that the controls were somewhat fitter than pwME, which is not surprising and is just a reflection of poor control selection. I honestly can't understand why they wouldn't have commented on the differences between the responses to the CPETs.
ME/CFS Science Blog
Senior Member (Voting Rights)
Been a while since I read this paper but think this is found in the test by group interaction of their ANOVA modelling.
Eddie
Senior Member (Voting Rights)
Do you remember which table that is?
Table 2 are the mean results by test at maximal exertion. Table 3 is the average difference between groups (but I don't think it shows the average difference between the tests by group which is what I think matters). Table 4 are the mean results at VAT.
ME/CFS Science Blog
Senior Member (Voting Rights)
Think it's mentioned in the text, not in a table.
Chandelier
Senior Member (Voting Rights)
Published back in April:
ME/CFS and Long COVID Demonstrate Similar Bioenergetic Impairment & Recovery Failure on 2-Day Cardiopulmonary Exercise Testing, 2026, Davenport et al.
Abstract
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is common in people with Long COVID, including post-exertional malaise (PEM).
The overlapping observation of PEM in pre- and post-COVID forms of ME/CFS suggests the potential for shared bioenergetic impairments, but this has not yet been demonstrated.
Two cardiopulmonary exercise tests (CPET) administered 24 h apart can elucidate the metabolic underpinnings of each disease.
This retrospective study examined physiological responses during two-day CPET in people with ME/CFS (63 females/21 males), Long COVID (52 females/27 males), and matched non-disabled control participants (51 females/20 males).
Data were analyzed within sexes using repeated measures analysis of variance.
All participants met maximal effort criteria.
There were significant reductions in oxygen consumption (VO₂) and workload at the ventilatory anaerobic threshold (VAT) in both patient groups compared to non-disabled controls, with larger effect sizes at VAT than at peak exertion.
Performance decrements were observed in both sexes.
Females exhibited more pronounced abnormalities and significant group by test effects.
No significant differences were observed between patient groups.
Severe disability based on impaired VO₂ was prevalent in both patient groups.
Hemodynamic and ventilatory measures were within normal ranges.
ME/CFS and Long COVID both involve a functionally significant bioenergetic failure complicated by inadequate post-exertional recovery, which is similar between the conditions and unexplained by hemodynamic and ventilatory changes.
Findings support the utility of two-day CPET as an objective measure functional impairment in ME/CFS.
Future studies may integrate mechanistic biomarkers with two-day CPET as trial endpoints and to establish likely responses to treatments for PEM.
Web | DOI | PDF | Clinical & Translational Metabolism | Open Access
ME/CFS and Long COVID Demonstrate Similar Bioenergetic Impairment & Recovery Failure on 2-Day Cardiopulmonary Exercise Testing, 2026, Davenport et al.
Davenport, Todd E.; Stevens, Staci R.; Stevens, Jared; Van Ness, J. Mark
Abstract
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is common in people with Long COVID, including post-exertional malaise (PEM).
The overlapping observation of PEM in pre- and post-COVID forms of ME/CFS suggests the potential for shared bioenergetic impairments, but this has not yet been demonstrated.
Two cardiopulmonary exercise tests (CPET) administered 24 h apart can elucidate the metabolic underpinnings of each disease.
This retrospective study examined physiological responses during two-day CPET in people with ME/CFS (63 females/21 males), Long COVID (52 females/27 males), and matched non-disabled control participants (51 females/20 males).
Data were analyzed within sexes using repeated measures analysis of variance.
All participants met maximal effort criteria.
There were significant reductions in oxygen consumption (VO₂) and workload at the ventilatory anaerobic threshold (VAT) in both patient groups compared to non-disabled controls, with larger effect sizes at VAT than at peak exertion.
Performance decrements were observed in both sexes.
Females exhibited more pronounced abnormalities and significant group by test effects.
No significant differences were observed between patient groups.
Severe disability based on impaired VO₂ was prevalent in both patient groups.
Hemodynamic and ventilatory measures were within normal ranges.
ME/CFS and Long COVID both involve a functionally significant bioenergetic failure complicated by inadequate post-exertional recovery, which is similar between the conditions and unexplained by hemodynamic and ventilatory changes.
Findings support the utility of two-day CPET as an objective measure functional impairment in ME/CFS.
Future studies may integrate mechanistic biomarkers with two-day CPET as trial endpoints and to establish likely responses to treatments for PEM.
Web | DOI | PDF | Clinical & Translational Metabolism | Open Access
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Jonathan Edwards
Senior Member (Voting Rights)
I don't really understand why Davenport did not present these findings as part of the AfME Webinar. (Maybe he did and I missed it.)
They were different in the preprint (fig 2 vs fig 3), so that looks like a publishing error.
On the web page https://link.springer.com/article/10.1007/s12018-026-09326-0/figures/3 comes up blank for me. Either that's part of the error or they're aware and in the process of fixing.
On the web page https://link.springer.com/article/10.1007/s12018-026-09326-0/figures/3 comes up blank for me. Either that's part of the error or they're aware and in the process of fixing.
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Eddie
Senior Member (Voting Rights)
I wonder if there reviewers saw the male VAT graphs because they aren't included in this paper at all. Maybe an earlier preprint had the graphs mixed up.
The male VAT graph that is missing is the one which does not support this claim:
While the ME/CFS group had lower workload at VAT to begin with, there was no decrease between the two tests. There was a decrease in the controls. They never discuss why healthy controls workload would decrease between the two days. They mention the fact that prior studies have found this but fail to mention that the males in this study directly contradict that finding.
Sorry to bang on about this but it seems like the authors must have known this finding is in opposition to what they claim but decided not to discuss it (it being missing from the graphs also doesn't help).
The male VAT graph that is missing is the one which does not support this claim:
While the ME/CFS group had lower workload at VAT to begin with, there was no decrease between the two tests. There was a decrease in the controls. They never discuss why healthy controls workload would decrease between the two days. They mention the fact that prior studies have found this but fail to mention that the males in this study directly contradict that finding.
Sorry to bang on about this but it seems like the authors must have known this finding is in opposition to what they claim but decided not to discuss it (it being missing from the graphs also doesn't help).