An insulin based model to explain changes and interactions in human breath-holding

[HydroApprentice]

Has anyone access to this? Sounds like an interesting read [emoji4]

http://www.sciencedirect.com/science/article/pii/S0306987715000870

Abstract

Until now oxygen was thought to be the leading factor of hypoxic conditions. Whereas now it appears that insulin is the key regulator of hypoxic conditions. Insulin seems to regulate the redox state of the organism and to determine the breakpoint of human breath-holding. This new hypoxia–insulin hypotheses might have major clinical relevance. Besides the clinical relevance, this hypothesis could explain, for the first time, why the training of the diaphragm, among other factors, results in an increase in breath-holding performance.

Elite freedivers/apnea divers are able to reach static breath-holding times to over 6 min. Untrained persons exhibit an unpleasant feeling after more or less a minute. Breath-holding is stopped at the breakpoint. The partial oxygen pressure as well as the carbon dioxide pressure failed to directly influence the breakpoint in earlier studies. The factors that contribute to the breakpoint are still under debate.

Under hypoxic conditions the organism needs more glucose, because it changes from the oxygen consuming pentose phosphate (36ATP/glucose molecule) to the anaerobic glycolytic pathway (2ATP/glucose molecule). Hence insulin, as it promotes the absorption of glucose, is set in the center of interest regarding hypoxic conditions. This paper provides an insulin based model that could explain the changes and interactions in human breath-holding. The correlation between hypoxia and reactive oxygen species (ROS) and their influence on the sympathetic nerve system and hypoxia-inducible factor 1 alpha (HIF-1α) is dealt with. It reviews as well the direct interrelation of HIF-1α and insulin. The depression of insulin secretion through the vagus nerve activation via inspiration is discussed. Furthermore the paper describes the action of insulin on the carotid bodies and the diaphragm and therefore a possible role in respiration pattern.

 

[MarcinB]

PM me if you are interested.

 

[HydroApprentice]

Thanks, the issue has been successfully resolved [emoji16]

 

[growingupninja]

Interesting. When i am in full blown ketosis (insulin levels very, very low) the comfort stage of breathhold is noticeably higher than normal. But unfortunately comfort does not equal O2 conservation; for dry static i burn O2 at an accelerated rate and bradycardia/vasoconstriction arrive later during ketosis, when I measured with pulse oxy monitor.

 

[Azrael3000]

while I do not fully understand the paper, it seems this is only a hypothesis, no experiments or validation. @MarcinB what is your opinion on it?

 

[HydroApprentice]

It's pretty convoluted, and I also don't really see any added value for our discussions. But I think it could be worthwhile to have a look through the list of references.

 

[MarcinB]

I haven't read it yet. I'll post my comments when I'm done with it.

 

[MarcinB]

I've finally read this review. The author hypothesizes that almost everything that happens during breath hold is related to insulin (activation of chemoreceptors, diaphragm contractions, samba etc.). In my opinion the paper is way too speculative and the quoted studies do not adequately support the hypothesis that insulin plays a key role during breath-hold. Nevertheless some ideas are interesting e.g. involvement of insulin in body adaptation to hypoxia induced by training. There might be something in it, but in my opinion it's too early to tell that insulin is an important factor in freediving physiology. It seems that there are no studies yet where insulin was investigated in the context of breath holding (at least such study was not cited in this review).

 

[growingupninja]

There is actually a very strong interplay between EPO and insulin which has not been studied. There are a few rat studies related to ketogenic diet, insulin, and EPO supplementation, but it does seem a little speculative to attribute everything to one hormone.

 

[HydroApprentice]

Yeah, I'm also asking myself whether this is relevant for the time frames we're talking about. I'd assume that such a basic hormonal feedback system including the blood sugar regulation can't be "unbalanced" for a couple of breath holds within minutes.
But that's only gut-feeling, really, and I base this statement on absolutely nothing.

 

[Kray]

Thanks MarcinB for the paper. I didn't really understand it. What I get from the first reading is diaphragmatic contraction increases insulin level which helps burning sugar in blood increasing apnea time.

Insulin triggered my interest because last week I took a couple of blood sugar tests for fun. It read about 97 for 2 days which is unusually high for non-diabetes in the morning before food, although 2 hours after eat it stayed the same. I tried to think what could have caused the high sugar level reminding me of the habit of drinking 2-3 cups of coffee a day while off training. Google say that coffee can impair insulin sensitivity. After quitting coffee for 4 days, I got 83. So in my case, coffee must have something to do with insulin level/blood sugar. I will keep monitoring it.

But I'm still not sure if it's is good or bad. I know for a fact that, for me, drinking coffee before rec dive is okay, but performance dive is absolute no no. While I was training, I had coffee right after diving session. Next mornings, I was doing fine, even able to set a few PBs on 3 mins dives with clear head. I didn't know coffee effect can last that long. Maybe with the right amount and the right time of intake it can help keeping blood sugar high to burn on hypoxic event.