Cognitive fatigue due to exercise under normobaric hypoxia is related to hypoxemia during exercise, 2022, Genta Ochi et al

Abstract

We previously found that a 10-min bout of moderate-intensity exercise (50% maximal oxygen uptake) under normobaric and hypoxic conditions (fraction of inspired oxygen [FIO2] = 0.135)
reduced executive performance and neural activity in the left dorsolateral prefrontal cortex (DLPFC).

To examine whether this cognitive fatigue is due to a decrease in SpO2 during exercise, we compared executive performance and related prefrontal activation between two experimental conditions, in which the participants inhaled normobaric hypoxic gas (FIO2= 0.135) hypoxic exercise [HE]) or hypoxic gas adjusted so that SpO2 during exercise remained at the resting level (milder hypoxic exercise [ME]). ME condition showed that reaction time in executive performance decreased (t[13] = 2.228, P < 0.05, d = 0.34, paired t-test) and left DLPFC activity increased (t[13] = -2.376, P < 0.05, d = 0.63, paired t-test) after exercise compared with HE condition.

These results showed that the HE-induced reductions in the left DLPFC activity and executive performance were both suppressed in the ME condition, supporting the hypothesis that exercise-induced cognitive fatigue under hypoxic environment is due to hypoxemia during exercise. This may lead to the development of a method of coping with cognitive fatigue due to exercise that causes hypoxemia.


https://www.nature.com/articles/s41598-022-14146-5

 

I'm interested in this but don't have the brainpower currently to do the 'put it together thoughts' it probably deserves. My gut is that in the past sometimes my cognitive symptoms have seemed like this (and I have enough CO detectors around my home to prove this, particularly in the past). I'm not sure what has occured as I have got worse is that, although B12 injections helped a lot, certainly in the days after vs days before.

I have also definitely always since a teenager had an air thing - windows open overnight even if freezing otherwise wake up with worse issues and feel like I'm suffocating and wake in middle of night. ALso have had symptoms that have very much felt like oxygen issues are involved. But this is far from forensic on what they mean - just really surely showing the level of this group matches another group in a certain hypoxic situation when exercising. Given how variable ME is (and other individuals) I'd need more.

I hate how all of the different 'component bits' get mixed up by those you talk to who think 'sleep' or tiredness or this - the patient knowledge is huge in knowing which bits are due to these factors on top of things that occur during other patterns. I really do think it is a big problem that 'cognitive' is 'lumped'. Even worse when it is neurological anything, like whether you can't wake up vs can't think of words or do 'complex' (you don't realise they are until you get ill enough to realise thinking of an answer to a question you've heard then answering it is huge) cognitive stuff is 'the same'. 'the fog' isn't accurate, and any fogginess doesn't coincide with all the cognitive symptoms as an explanation so it is infuriating reading through things without detail defined.

I also think the effects of exercise are key, and am glad someone is looking into this in this way just for a start (rather than other 'approaches'). Yes exertion of any kind affects cognitive fatigue for me. Physical slightly differently to cognitive (hence the 'defining things better' of what we mean above).

I like the idea there might be a literature on Overtraining syndrome' - not because that is what ME is, but because the lowered resilience of the body from whatever has happened to it means exertion is 'somewhat like' 'overtraining' if you had to find something to 'group it to'. By that I mean your body is 1% so having to do 2% isn't far off an overtraining athlete. We don't know how much of ME is 'cumulative' in those who have had it longer, severities (which tend to mean harder to avoid overexertion when it's noise or light) - and this is pretty key for those many of us who haven't been well supported.

I don't like that horrible punchline I can see on it where some idiot HCPs then think the same approach for a previously healthy OTS maps to ME as if there isn't an underlying cause reducing baseline rather than overexertion of normal body underlying it.