Diving response or survival response? Is a freediver fitter?

[perow1]

First of all i want to give some background to my real question. Maybe this is a general accpted theory clinical, but it struck me when i was watching a tv-show featuring critical situations. A young man had been stuck under the snow for nearly twenty minutes without air. For a long time I have been thinking in terms that the diving response(DR) is really a survival response(SR) Evolutionary it seems more plausible that human beeings have a SR rtather than a DR. Despite the fact that I stand behind the "aquatic ape hypothesis" to some extent it seem to be a simpler explanation that the response we are talking about and are trying to train is a result from natural selection originating from the fact that humans with their large brains and wits tend to subject themselves to various situations that result in disaster.

A human beeing must be able to cope with situations where they cannot save themselves by other means than blacking out and saving crucial oxygen. To me it seems unlikely that humans have evolved under such extreme situations enabling us to go past 100m CWT and 200m NLT and STA +10 mins. I agree that we most likely are descendants from some sort of aquatic apes, but never the kind of apes that expose themselves to depts past 30m. We may have evolved to stay in the "wet environment" but the response is really a way to cope with accidents when they occur.

No matter what you think of my background speculation I have a question to which i wish to hear your thoughts.

When I first heard about the young man that had been buried under the snow for twenty minutes, my ego kicked in. The thought that I as a freediver with the ability to hold my breath past six minutes would cope with oxygen deprivation much better than the average person, then I started to think.

Wouldn´t it be likely that I or any other freediver would stay concious for a longer time and spend more oxygen than an ordinary person? The ordinary person may blackout and go into the natural extreme version of the SR-mode erlier than a freediver who is trained to use the early part of the SR/DR in their sport and to stay concious and produce results. On the other hand would a freediver be trained to exist under low oxygen conditions and have a greater buffer system than an untrained person. My question to you all is really;
Is a freediver more or less fit to survive a disater? Probably more, but wouldn´t it be bad to delay the blackout?

[cebaztian]

Less I would say, especially in a REALY extreme situation, as in your first situation.
But...
Where it takes a 2-3 minute breathold to deal with a situation - the freedivers survive - other lesser creatures (:-) panic and die.

Sebastian

[Alison]

I was in a situation like that last Christmas, I was trapped underwater by a boat that had hit me in the chest, breaking my ribs and sternum, I was under the water with empty lungs for perhaps a minute realisticly but it felt a lot longer. I dont know about a survival instinct but I was totally panicing, I often think about this and can only assume that I survived that by being a freediving type and having the associated fittness that goes with it I kept concious.

[efattah]

- I believe that it is a survival response rather than a dive response
- I believe that a freediver would survive longer or have a better chance at survival in such a situation. The longer you delay the blackout, the better, and best of all the freediver is able to black-out with full lungs, drastically increasing survival time. Blacking out with empty lungs reduces your survival time, and inhaling water or snow or anything else will drastically reduce your survival time.

Alison, amazing that you were under water for that long being crushed, with empty lungs. I don't remember you mentioning that in your earlier versions of the disaster story. Inspirational!

[Alison]

I only ever mentioned it once Eric, I dont really like talking about it though its in my mind most of the time. My recollection of the whole thing is vauge except that bit. I dont think it was any form of response, just that my body delt with the situation at that moment for whatever reasons, I like to think that diving had something to do with it but I certainly didnt keep my head

[Ricochet]

In my opinion a black out is not a protection mechanism to save oxigen. Its just a step in the process of losing your body functions towards death.
We don't have sambas to save O2, do we?

[aydin]

Of course you are right Ricochet,rather than saving we loose O2 when the samba occurs.

[Ricochet]

The Samba thingy wasn't ment to be serious
I just wanted to illustrate that blackouts and sambas are alike and that blackouts are not there to save us oxigen, but that they are there because we lack of it.

[aydin]

Yes Ricochet,in the samba the little contractions of our muscles uses not saves O2,in the blackout this process get worsen of course.I just wanted to explain this phenomenon.

[DrLindholm]

Well, the diving response is triggered by apnea per se, i.e you dont need water. It is "conserved" through the evoulutionary tree, in fact if you take fish out of water it will have a "diving response" , so it is more of a survival response to asphyxia and apnea but it is conveniently called the diving response in humans. For some reason it is stimulated by cold water in the face during apnea, which have been used to support the aquatic ape theory, but that theory is based on many other facts and whether it is true or not is probably not dependent on a diving response. Diving mammals have a more pronounced diving respons that they seem to be able to control depending on their diving strategy (i.e short dives no respons, long dives or when in danger a strong response).
In most humans (non-freedivers ) the diving response is probably mostly something important before you are born, as a survival response if there is any problems before you start breathing air.

However it is very interesting for a freediver and there are some evidence that it is possible to train your diving response, which is what most of the readers on this list do frequently...

Peter

[ADR]

DrLindholm, what do you feel are the most effective ways to train the diving response?

thanks

[DrLindholm]

There are no clear scientific evidence to what is the best method of training your diving response. It has been shown to improve both with resting and exercising apnea training.

Peter

[ADR]

I have been surfing your website, thanks for making the materials available to us.

regards

[ADR]

...I forgot to ask, is it accurate to read the Pulsatile Value (PIr) from a pulse oximeter as an indicator of vasoconstriction/vasodilation (when using a fingertip sensor)? I posted a thread on this a week or so ago but did not get a response from anyone?

I have noticed that during hyperventilation the PIr value is high, possibly due to vasodilation and during the struggle phase of apnea it drops to very low values(possibly due to vasoconstriction) The unit provides HR so Bradycardia can be measured and I was just wondering if the PIr value actually also shows relative Vasoconstriction

[efattah]

During my own experiments with oximeters, the fingertip perfusion value would always decrease during the static, to very low levels at the end, and then it would jump drastically high right after I would start breathing. It may be a worthwhile method to measure the hypoxic-response (note that I avoid the term dive response...)