Exhale dry static

[cdavis]

James: the continued drop in 02 reading represents the time it takes for the oxygenated blood to reach the measuring device. What the device measures and what your brain experiances aren't the same unless you have a sensor on your carotid arteries

 

[james_spearo]

James: the continued drop in 02 reading represents the time it takes for the oxygenated blood to reach the measuring device. What the device measures and what your brain experiances aren't the same unless you have a sensor on your carotid arteries

I think there's a little more to it than that, it's not a continual drop its a sharp drop from 70 to 50 within a few seconds of the first inhale. I was speaking with my pool training partner whom is a registered nurse and he called it "post apena" hypoxic something... can't exactly remember, I'll ask him again. Could also be due to vasoconstriction, as it's on my finger.

And @chad, I have been doing full exhale holds. I bend forward a little to push the last bit of air out. No reverse packing as of yet

 

[cdavis]

I'd be interested in what your training buddy has to say. Vasoconstriction will definitely slow down the blood flow out to the finger sensor.

There is something odd about some blackouts and similar things that might relate to "post apnea" hypoxia. I've seen several open water BOs and the physical changes you see as the diver comes around sometimes don't match how long it takes for the oxygenated blood to reach the brain. Its almost as it the body realizes it can relax ( or use its last reserves?) once breathing is resumed.

 

[growingupninja]

They appear to be the bodies reaction to extreme compression of the chest. I agree that they involve more and different muscles than a normal contraction, not sure exactly what all. My first were on my first attempts at deeper diving. Somewhere around 80 ft full lung, my chest went nuts, crazy strong heave, I had do idea what was happening. After my body figured out that chest compression was ok, pressure contractions got less and less, pretty much gone now.

Pressure contractions are talked about so little, that I wonder whether all divers get them.

Marcin, would you define "mild hyperventilation"?

Chad, when I get a pressure contraction, dive is over, I immediately either come up a lot or inhale. Sometimes dry, I can feel just the start of a pressure contraction and can suppress it, not always.

Pressure contractions are very easily overcome when diving with a mask because there's some give in the mask. When switching from mask to noseclip they are usually the limiting factor since the noseclip doesn't have any give. I've been diving/training past 200' for years at this point and I can barely make it to 30M in just a noseclip.

 

[Kray]

i just did a pb of empty lung(exhale all but not force it out after comfortable) static of 3.50 . I used to get about 3 after heavy hyperventilation, but this time after contraction started, I imagined doing 10 dnf stokes which, in the water, usually gets me to almost hypoxic on empty lung. So there's a of mind game involves indeed I think

 

[osksa]

I do dry static on empty lungs too regularly. I wish I knew for sure they helped, but I'm stuck with hoping as most apnea training... And I am far from the exhale champions in this thread. I have done 8 min once on full lungs, but with empty lungs and heavy hyperventilation I seldom reach over 2 min. I think I held 2:30 once. The anxiety and urge to breath is just huge for me. SaO2 in finger at around 70 % after a two minute hold.

Anyway, after doing heavy dry static training, exhale or not, I tend to see the SaO2 drop during the hold and about 30 s after I start to breath. Then it returns to 99-100 %, and stays there for about 20 secons, and then it drops again to 90-95 and stays so for several minutes if I stay still on my back. My urge to breath is very low. I am breathing but very little. Feels like I dont have to breath almost, but I am not forcing anything, just letting breathing be as the body wishes. Anyone else seeing this second drop? Wondering what could be the reason...

 

[MarcinB]

I think it may be due to post-apnea hypoventilation. You're breathing so slow and shallow that O2 in your lungs drops below normal level. It looks like the sensitivity of your chemoreceptors decreases after heavy apnea training.

 

[osksa]

That is the theory I believe in too. But do you know for sure that such an effect exists? Is it common knowledge? Our club medic thinks it is just bad blood circulation in the finger after the breathhold... So that there may well be little oxygen in the finger, but not centrally...

 

[growingupninja]

I agree, I think it is a post apnea condition. After apnea my breathing response is very muted if I am at rest. I have even experienced a few minutes of significant bradycardia with normal relaxed breathing after the initial first breath spike in pulse. Somebody else on DB also mentioned it has happened to them as well.

In general, PO2 sat values of mid nineties are considered perfectly normal for fit and healthy adults at rest, although with a few deep breaths it should rise to 98 or 99.

Sent from my SM-G930T using Tapatalk

 

[MarcinB]

The fact that apnea training can decrease ventilatory response to CO2 is quite well proven. There are one or two studies showing that chemoreceptor sensitivity does not change after single session of static breath hold, however, as far as I remember these studies were done on untrained subjects.

Vasocontriction stops almost immediately when breathing is resumed. It can be clearly seen on pulse oximeter showing perfusion index. In my opinion the SpO2 values you observe are correct. The fact that the urge to breathe is decreased strongly suggests diminished chemoreceptor sensitivity.