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Predicting post-exertional malaise in Gulf War Illness based on acute exercise responses (Boruch et al., 2021)

Discussion in 'Health News and Research unrelated to ME/CFS' started by Nightsong, Jun 14, 2021.

  1. Nightsong

    Nightsong Established Member (Voting Rights)

    Aims: Post-exertional malaise (PEM) is poorly understood in Gulf War Illness (GWI). Exercise challenges have emerged as stimuli to study PEM; however, little attention has been paid to unique cardiorespiratory and perceptual responses during exercise. This study tested whether select exercise parameters explained variability in PEM responses.

    Main methods: Visual analog scale (0-100) versions of the Kansas questionnaire were used for daily symptom measurements one week before and one week after 30-min of cycling at 70% heart rate reserve in 43 Veterans with GWI and 31 Veteran controls (CON). Cardiopulmonary exercise testing (CPET) methods were used to measure oxygen (VO2), carbon dioxide (VCO2), ventilation (VE), heart rate, work rate, and leg muscle pain. Symptom changes and CPET parameters were compared between groups with independent samples t-tests. Linear regression (GLM) with VE/V CO2, cumulative work, leg muscle pain, and self-reported physical function treated as independent variables and peak symptom response as the dependent variable tested whether exercise responses predicted PEM.

    Key findings: Compared to CON, Veterans with GWI had greater ventilatory equivalent for oxygen (VE/VO2), peak leg muscle pain, fatigue, and lower VCO2, VO2, power, and cumulative work during exercise (p < 0.05), and greater peak symptom responses (GWI = 38.90 ± 29.06, CON = 17.84 ± 28.26, g = 0.70, p < 0.01). The final GLM did not explain significant variance in PEM (Pooled R2 = 0.15, Adjusted R2 = 0.03, p = 0.34).

    Significance: The PEM response was not related to the selected combination of cardiorespiratory and perceptual responses to exercise.

    Kitty, Sean, Yessica and 6 others like this.
  2. cassava7

    cassava7 Senior Member (Voting Rights)

    This seems to be the second study on PEM in GWI from this group at the University of Wisconsin-Madison; the first one was published in 2019.

    However, both studies involved a single CPET and the authors do not mention the 2-day CPET protocol for ME/CFS in this paper, whether in the introduction or in their discussion of the results.

    ETA: deleted the paper/attachment.
    Last edited: Jun 15, 2021
  3. Hutan

    Hutan Moderator Staff Member

    New Zealand
    Yes, it's strange. You would think, if you were aware of the term 'post-exertional malaise' and the use of 2-day CPET results to study it in ME/CFS, that that is what you would be wanting to replicate in GWI. Perhaps the aim was to get a conclusion that sounds a lot like 'PEM is not related to any measurable aspect of exercise'. All of the 12 authors are affiliated to either, or both, the
    • William S. Middleton Memorial Veterans Hospital, Madison, WI, United States of America, or,
    • War Related Illness and Injury Study Center, Department of Veterans Affairs New Jersey Health Care System, East Orange, NJ, United States of America.
    From the abstract, it's a bit hard to tell, but it does seem that the GWI people did record greater symptom changes following exercise - it's just that the symptom changes weren't related to the exercise parameters measured. It would be good to see 2-day CPET tests in all the illnesses that look like ME/CFS - GWI, ME/CFS-like forms of Long Covid, Q-fever fatigue syndrome, post-Ebola fatigue syndrome, post-treatment Lyme. I can't recall seeing any of those.?
    Michelle, cassava7, Kitty and 6 others like this.
  4. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

    Simply put, this means that the level of cardiovascular fitness was not related to PEM in this group of patients.
    Michelle, FMMM1, Kitty and 5 others like this.
  5. Sean

    Sean Senior Member (Voting Rights)

    So neither physical deconditioning nor pathological interoception have any explanatory power for GWI?
  6. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

    That is what the evidence in this study suggests.
    Michelle, FMMM1, Kitty and 4 others like this.

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