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The Conversation: VO₂max: the gold standard for measuring fitness explained

Discussion in 'Other health news and research' started by Ravn, Jan 27, 2019.

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  1. Ravn

    Ravn Senior Member (Voting Rights)

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    Mostly an article by sports scientists exhorting us all – well, maybe not us specifically – to exercise more. However, the article mentions an interesting working hypothesis (no published papers on this that I could find, not looking very hard though). Bolding mine.

    https://theconversation.com/vo-max-the-gold-standard-for-measuring-fitness-explained-109486

    If we assume for a moment the hypothesis is correct, how would that fit in with 2-day CPET results where PwME typically have near normal VO2max on day 1 but significantly lowered VO2max on day 2? Surely we don't have a significant amount of blood going awol overnight?
     
    Ravn, Jan 27, 2019
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  2. ScottTriGuy

    ScottTriGuy Senior Member (Voting Rights)

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    Maybe it is the transportation that is weakened by day 2 of CPET?
     
    ScottTriGuy, Jan 27, 2019
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  3. Jonathan Edwards

    Jonathan Edwards Senior Member (Voting Rights)

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    The hypothesis looks wrong to me.
     
    Jonathan Edwards, Jan 27, 2019
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  4. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Seems wrong to me, there is an association with blood volume, but it is not the only association.

    It is intriguing though as my major PEM symptoms are circulation related.

    The performance drop on the 2 day CPET in ME patients is primarily lower power at the ventilatory threshold, rather than a drop in VO2... The reason why some patients cannot reach their prior VO2max is due to leg fatigue - the legs simply are not putting out the same power at the same level of neural drive (which is directly related to effort perception) anyone who has done the test will know this. The reason why some patients are able to match their prior VO2peak is because they didn't actually reach VO2max on the first day.
     
    Last edited: Jan 27, 2019
    Snow Leopard, Jan 27, 2019
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  5. Hutan

    Hutan Moderator Staff Member

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    From
    https://us.humankinetics.com/blogs/excerpt/dehydration-and-its-effects-on-performance

    So, dehydration lowers VO2max. It's interesting, given how people with ME have said they feel better with saline infusions and (I think) medications for orthostatic intolerance that increase blood volume.

    Could it be that, after exertion, fluid that should be in the circulation system is pooling elsewhere e.g. in the lower legs and abdomen?
     
    Hutan, Jan 27, 2019
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  6. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    There have been some further questions and answers by one of the authors that some may find interesting.

    The conclusion is that while haematological factors are central to VO2Max, blood volume might not always be the rate limiting factor.

    One of the authors suggested that peripheral factors can be relevant in untrained participants (where training specifically relates to the muscles used in the test) and some testing conditions, VO2Peak can be limited (below VO2Max) by the volume of working muscle and limited peripheral blood flow.
    https://www.ncbi.nlm.nih.gov/pubmed/26614395
     
    Snow Leopard, Jan 29, 2019
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