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PEM - What do physical and mental exertion have in common?

Discussion in 'General ME/CFS Discussion' started by Marco, Jan 7, 2015.

  1. Marco

    Marco Grrrrrrr!

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    I'm just asking the question - I don't have an answer:)

    Most studies purporting to study PEM use various forms of physical exercise yet we know that mental exertion can also cause PEM. Whether its the same PEM is debateable but I know that I get the same painful and heavy limbs following mental exertion and conversely physical exertion causes cognitive problems as well as the expected physical ones.

    To provoke a reaction (PEM) physical and mental exertion must be producing a signal of some description (an effector?) but which signal would they have in common?

    Vigorous exercise causes microlesions in muscle tissue prompting the production of heat shock proteins that chaperone cellular repair mechanisms. The Lights' work shows increased expression of pathways signalling fatigue and pain following physical exercise.

    With mental exertion we can easily rule out microlesions and its unlikely that pain signalling would be involved (even if subjectively thinking makes your head ache). 'Fatigue signals' are a possibility but its not clear that the same pathways might signal muscle fatigue and neural fatigue.

    Both activities of course require energy but as the interesting Scientific American article below discusses, the brain actually consumes a large amount of energy in its 'resting' state and difficult tasks don't really significantly affect that :

    http://www.scientificamerican.com/article/thinking-hard-calories/

    Both activities may also be perceived as stressful but again from personal experience an enjoyable non physical activity can wipe me out as easily as an unpleasant one.

    As I said I don't have the answer but I think its a question worth asking.
     
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  2. duncan

    duncan Senior Member

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    I think it is a false dichotomy. The brain is an organ. Exert it, and as with any other exertion levied against muscles or organs etc., a toll may be exacted.

    The commonality between mental and physical PEM is exertion, but even that is illusory. Both instances of PEM are physical. Physical dynamics are at play always.
     
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  3. Marco

    Marco Grrrrrrr!

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    @duncan

    Yes indeed but exertion must produce something which leads to the perception of fatigue and triggers the delayed recovery in PEM. What is or are the something(s)?
     
  4. Vic

    Vic

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    I think it's because we think with our bodies. When we do a cognitive tast that is difficult or if we are emotionally involved, we physically tense up certain muscle fibers in our face, shoulders, chest, back, hips. Other than that we pay less attention to our breathing. It becomes shallower and we start to get behind on our O2 intake/CO2 expulsion.
     
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  5. adreno

    adreno PR activist

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    Mental exertion causes energy expenditure and increase in ROS, inflammation and brain lactate.
     
  6. Vic

    Vic

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    Too small. Think bigger. CFS isn't caused by many individual cells functioning at a suboptimal level. There is something else systemic that is causing the widespread cellular dysfunction.
     
  7. Marco

    Marco Grrrrrrr!

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    Good suggestion. But do high levels of oxidative stress cause fatigue. They do appear to in chemotherapy treatment where mitochondrial dysfunction/oxidative stress have been linked with chemo fatigue, chemo fog and neuropathy but its clear that the chemo agent is causing the problem and I'd like to have a clearer idea of how this leads to a perception of fatigue.

    With ME/CFS we don't have a toxin and I also hate to shift the goalposts but what would make oxidative stress a problem (or at least more of a problem) following onset?
     
  8. adreno

    adreno PR activist

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    As I understand it, our energy reserves are low. When we increase activity (physical or mental) energy is shunted towards NADH (ATP) production, and away from NADPH. This will cause ROS and lactate to rise. Now, can high ROS and lactate cause PEM? It seems that many are experiencing relief from PEM with bicarbonate. Rest and antioxidants also seems to help with PEM (as they bring down ROS). There are a few threads going on about this at the moment:

    http://forums.phoenixrising.me/inde...ods-and-can-cfs-people-get-really-well.34385/
    http://forums.phoenixrising.me/inde...a-sam-e-catalase-no-pem-after-exercise.34446/
     
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  9. Marco

    Marco Grrrrrrr!

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    OK but as per the article I posted it seems that mental exertion doesn't add much extra burden to the brain's energy requirements.
     
  10. Mij

    Mij Senior Member

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    I'm not sure either, but when I over exert physically it also drains my mental energy, and vice versa. I experience calf muscle fatigue and weakness when I overuse my brain.
     
  11. MeSci

    MeSci ME/CFS since 1995; activity level 6?

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    Maybe the brain has a very narrow threshold of tolerance? Apparently, scans have shown that we use many more brain areas when thinking than do people without ME. That could mean that we reach a threshold of tolerance more quickly.
     
  12. Vic

    Vic

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    No, oxidative stress does not cause immediate fatigue. Oxidative stress is a long-term damager of cells and mitochondria. It is part of the equation, but is never strong enough to knock you out in itself.

    If that is the case, WHY are the energy reserves low? Why does rest not recover your energy sufficiently in a normal amount of time?

    Question for you: would you describe yourself as barrel-chested?
     
  13. adreno

    adreno PR activist

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    This could be due to mitochondrial dysfunction. But no one knows. However, if you read the threads I linked to, you will get a clearer view of this.
     
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  14. NilaJones

    NilaJones Senior Member

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    I think emotional stress gives me worse PEM than mental effort. Thinking effort is more just either possible or not possible.

    This could be because emotion involves more whole-body stuff? Adrenals, heart, skeletal muscle, gut, etc.?
     
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  15. Marco

    Marco Grrrrrrr!

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    I think that's possibly the same for me or at least the two are pretty equal.
     
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  16. Mij

    Mij Senior Member

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    @Vic not I'm not barrel-chested. Why do you ask?
     
  17. daisybell

    daisybell Senior Member

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    I believe the answer lies deep in the brain/brain stem... In the 'primitive' bit. I don't know what is happening, but it has to be some neurotransmitter or hormone that sends a strong signal which starts the cascade of PEM (to my mind). Otherwise the breadth and disparity of the symptoms don't make sense as a picture.
     
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  18. Vic

    Vic

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    I've been trying to identify postural patterns. It's odd that your calves hurt when sitting. Mine get weaker when I sit a lot. Where else do you feel pain/tightness? Hah, I want to observe you!
     
  19. WillowJ

    WillowJ คภภเє ɠรค๓թєl

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    But that was in healthy people. It's thought that in PWME, it's needed to use many more regions of the brain simultaneously just to perform a cognitive lab test (relatively simple compared to real-life multi-tasking). This would be more like multiplying the base rate?
     
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  20. beaverfury

    beaverfury beaverfury

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    My banged together theory is that we could use our brains all day in 'default network mode' http://en.wikipedia.org/wiki/Default_mode_network, daydreaming or 'mind wandering' mode.

    It's 'mind focused' mode or task positive mode that causes problems for me. http://en.wikipedia.org/wiki/Task-positive_network . There seem to be more energy drain when I am trying to focus or achieve a task.
    And I can't dissociate task driven focus from some form of stress in our brain, however little, which I think kicks off part of our HPA axis which feeds into our whole me/cfs conundrum of dodgy cortisol and cytokine release, (subsequent microglial activation in the brain).

    Complex tasks which I learnt pre-me/cfs/lyme are easy enough to do by old habit. But If I had to learn something complex and new I am absolutely screwed.

    My experience is different here. If I am doing something enjoyable my brain seems to last far longer. (As long as I don't get too excited and stay relatively calm).
     
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