Dive reflex not always helpful?

[naiad]

I do a 2:00-3:00 breathe-up of deep breaths. For dry statics, on a good day I do warm-ups of 4:30, 5:00 then go for a max, about 5:30. In the pool I am more likely to do 3:30, 4:00 and then somewhere between 4:00 and 4:30.

I have tried just about every breathe-up and warm-up routine I have heard of, and nothing else works well for me. Shorter warm-up statics have little effect. Longer warm-ups are too tiring. A shorter breathe-up results in a strong urge to breathe and giving up early. A longer one has no positive effect.

 

[trux]

Here are two reasons:

1. Oxygen absorption through your skin
- Your skin absorbs a lot of oxygen, up to 8% of your body's requirement. Underwater this is not the case.

Not sure if you are exact here, Eric. As far as I could find, oxygen absorption at humans is usually estimated to lower levels. Diverse sources give values between 1% to 5% (for example here), usually rather at the lower end. 8% seems to be a lot, but I guess at some individuals under special circumstances it might be still possible. The values given in diverse documents also usually speak about the intake under normal conditions, and I do not exclude that the percentage may grow under hypoxia, or in apnea.

On the other hand, the body also gets rid of some CO2 in the same way - I did not find any values, but guess they may be similar to those of O2. And of course, vasoconstriction reducing the blood flow through the skin would reduce both the O2 intake, and the CO2 elimination through the skin.

There are indeed individuals who breath more than others through the skin - their skin is then often wet even at moderate temperatures, and not from sweating (for example persons referred in the document "The Osmotic Passage of Water and Gases through the Human Skin" eliminated through skin breathing 18g of water per hour)

In the same time, the claim that is not possible under water in not necessarily exact either (at least without a wetsuit). Although the full text of the above mentioned article is not available online, from the abstract and from other sources it is clear that gas and liquid exchange through the skin continue also under water. I am not sure about the levels - did not find any numbers anywhere, but there are diverse factors acting in both ways, so although I guess the levels would be lower than on air, I do not know if dramatically or not (Negative effects: lower oxygen percentage in water than in air; vasoconstriction, use of wetsuit, ... Positive effects: liquid osmosis; depth increases the partial osmotic pressure gradient of O2; high solubility of CO2 in water,...)

However, at Naiad it may be quite an amplified case: I found a document called An experimental study of oxygen absorption in some damselfly naiads. The full text is again not available, but from the title and the brief description it is apparent that damselfly naiads absorb oxygen through the skin much more intensively that humans, and that's the case even under water. So if Naiad is of a similar construction as damselfly naiads, it is no wonder she can hold her breath 6 minutes on the air, but not as long underwater - underwater she either has a 5mm wetsuit which prevents the gas exchange, or is too cold, having hence intensive vasoconstriction of skin capillaries, stopping the gas exchange in similar way as the wetsuit.

Now seriously: I think there are multiple factors playing role in Naiad's case (most already mentioned in this thread), but think that the skin respiration is not the principal one. From her description it is apparent that it is not the diving reflex in water that is not helpful, but rather the complete lack of it. One thing seems to be clear though: once the DR starts kicking in strongly, she will probably break some records She probably needs to spend more time with some real diving, than training dry on the bed - I guess it could help with improving the DR.

2. CO2 storage
- Under conditions of vasoconstriction & cold, your CO2 storage capacity is reduced.

I am not quite sure about this either. Better told, I believe there is indeed some reduction of CO2 storage with vasoconstriction, but maybe not that important. I'd be interested in seeing some documents talking about it closer. The vasoconstriction does not reduce the volume of blood in circulation importantly - it rather shifts it into the core, so the blood as CO2 buffer plays no big role. Possibly, the blood shift even improves the ratio of blood volume to the CO2 producing cells in the core. On the other hand, CO2 may be also stored in cells and liquids all over the body, so by limiting the delivery of the excess CO2 to the inactive parts may indeed play some negative role (especially at static apnea where the muscles produce little waste and could take some more off from the core if the vasoconstriction did not throttle it).

That told, I am not sure what the outcome exactly is, and would love to see some results of some serious research, but so far did not find anything specific.

 

[trux]

I do a 2:00-3:00 breathe-up of deep breaths. ...

Naiad, are you sure you do not hyperventilate? Breathing deeply for 2-3 min could easily drop your CO2 quite importantly, and that would explain the lack of diving reflex you described. It is true that without the hyperventilation, the difficult phase is much longer and harder, so it may push you to quit the breath-hold before you really need, but the consumption is normally much lower with a good DR (helped by high CO2) and hence the time much longer.

From your descriptions I have the impression that you achieve the long times rather thanks to hyperventilation (that also may give a hint for the relatively frequent BO's and sambas you experienced) than due to a good and strong diving reflex. I would suggest trying to train much more under relatively high initial CO2 level and with empty lungs - it sure is much more inconvenient, but should bring you to better results (and safer).

 

[adax]

AIDA warns! "training dry on the bed" can cause serious injuries! rofl

 

[trux]

AIDA warns! "training dry on the bed" can cause serious injuries! rofl

That's why freedivers use lubricants. Though that's entirely another topic - there are plenty of threads here on DB, better suited for that discussion

 

[naiad]

However, at Naiad it may be quite an amplified case: I found a document called An experimental study of oxygen absorption in some damselfly naiads. The full text is again not available, but from the title and the brief description it is apparent that damselfly naiads absorb oxygen through the skin much more intensively that humans, and that's the case even under water. So if Naiad is of a similar construction as damselfly naiads, it is no wonder she can hold her breath 6 minutes on the air, but not as long underwater - underwater she either has a 5mm wetsuit which prevents the gas exchange, or is too cold, having hence intensive vasoconstriction of skin capillaries, stopping the gas exchange in similar way as the wetsuit.

Now seriously: I think there are multiple factors playing role in Naiad's case (most already mentioned in this thread), but think that the skin respiration is not the principal one. From her description it is apparent that it is not the diving reflex in water that is not helpful, but rather the complete lack of it. One thing seems to be clear though: once the DR starts kicking in strongly, she will probably break some records She probably needs to spend more time with some real diving, than training dry on the bed - I guess it could help with improving the DR.

rofl rofl rofl
It may be the lack of dive reflex. Even with no breathe-up at all, and therefore no possibility of hyperventilation, my heart rate does not decrease significantly.

Naiad, are you sure you do not hyperventilate? Breathing deeply for 2-3 min could easily drop your CO2 quite importantly, and that would explain the lack of diving reflex you described. It is true that without the hyperventilation, the difficult phase is much longer and harder, so it may push you to quit the breath-hold before you really need, but the consumption is normally much lower with a good DR (helped by high CO2) and hence the time much longer.

From your descriptions I have the impression that you achieve the long times rather thanks to hyperventilation (that also may give a hint for the relatively frequent BO's and sambas you experienced) than due to a good and strong diving reflex. I would suggest trying to train much more under relatively high initial CO2 level and with empty lungs - it sure is much more inconvenient, but should bring you to better results (and safer).

The drop in heart rate is the same with or without the breathe-up, so I don't think it is to blame for the lack of DR. From my experience, a long struggle phase does not increase my total apnea time, and the stress increases O2 consumption, decreasing the time I can safely do. I have tried CO2 training, and while it increases my CO2 tolerance and therefore improves my performance, it does not seem to produce any DR.

I have tried empty lung training, but it feels awful, and still does not produce any DR. I am also very reluctant to do it in the pool, because of the risk of blacking out and breathing in water.

Maybe I am an unusual case - I simply don't have any significant dive reflex. One thing that does improve my performance is to do repeated statics or dynamics with short intervals in between. Maybe some sort of 'dive reflex' is triggered by apnea itself, whether dry or in water.

 

[trux]

Lucia, if you want to improve your diving response, you may want to read through the posts of Seb Murat or his articles available on the web (some links are listed here: murat @ APNEA.cz ). Actually couple of the things you are trying to avoid (i.e. stress, cold, high CO2,...) play important positive role in triggering proper DR. They sure do not make the breath-hold too easy or comfortable, but they do increase the diving response. I think it is important not only trying once or couple of times under such conditions (cold extremities, moderate stress, low breath-up,...) before rejecting that method and telling it does not work for you. At the beginning it may hinder your performance and force you to abandon the breath-holds prematurely, but with insisting little bit and repeating it in that way, the effect may be important.

 

[Waterysmile]

Lucia, I'm aiming to get back down to Richmond so if I can help in any way, then ask - I have wondered about switching to statics for a while.

 

[naiad]

Lucia, if you want to improve your diving response, you may want to read through the posts of Seb Murat or his articles available on the web (some links are listed here: murat @ APNEA.cz ). Actually couple of the things you are trying to avoid (i.e. stress, cold, high CO2,...) play important positive role in triggering proper DR. They sure do not make the breath-hold too easy or comfortable, but they do increase the diving response. I think it is important not only trying once or couple of times under such conditions (cold extremities, moderate stress, low breath-up,...) before rejecting that method and telling it does not work for you. At the beginning it may hinder your performance and force you to abandon the breath-holds prematurely, but with insisting little bit and repeating it in that way, the effect may be important.

Interesting, thanks for the link. I think stress does sometimes improve my performance - some of my best statics (dry and pool) and dynamics have been done when I am under stress, and others have been when I am totally relaxed, so maybe both can be helpful.

I have tried many, many statics and dynamics (literally hundreds) in cold conditions, and there has been no improvement in my response. The low breath-up is also something I have tried many times, and gave up on it because there was no progress.

Andrew, see you soon at Richmond, I will be doing statics again too.

 

[Ulf]

One thing that has been very helpful for me to improve my DR and vasoconstriction is diving in water temps of about 15-18 C. This really kicks in the vasoconstriction especially the lower temps in that range.
For me, pool temps does not seem to influence the vasoconstriction a lot and considering that the body reacts mainly to temperature differences and that those temps are actually higher than room temperature that makes sense. Maybe this could be changed by doing a lot of max attempts in the pool. Teaching the body that pool water means looong breath holds.
I think cold that is uncomfortable is detrimental to performance. I mean shivering or freezing.

(my 2 ore)

 

[Ulf]

BTW naiad, I should mention that most of the divers at the course that I saw do the test didn’t get a 50 % drop in heart rate. More like 30 % or less so what ever you got I don’t think you’re far away from the average diver…

 

[naiad]

That's a relief, then I am not that much worse than average!

One thing that has been very helpful for me to improve my DR and vasoconstriction is diving in water temps of about 15-18 C. This really kicks in the vasoconstriction especially the lower temps in that range.
For me, pool temps does not seem to influence the vasoconstriction a lot and considering that the body reacts mainly to temperature differences and that those temps are actually higher than room temperature that makes sense. Maybe this could be changed by doing a lot of max attempts in the pool. Teaching the body that pool water means looong breath holds.
I think cold that is uncomfortable is detrimental to performance. I mean shivering or freezing.

For me, anything less than 30C causes shivering and a drop in performance. The shivering starts a few minutes after getting in the water. My best pool statics and dynamics have been done when I am not cold at all. The cool water does cause vasoconstriction, but it also causes shivering and increases O2 consumption. If I could find a way round this problem, it would be a major breakthrough.

 

[DeepThought]

Lucia, I asked for your breath-up suspecting the same reasoning Trux mentioned in his post. I think that hyperventilation might be getting the better of you.

It may be the lack of dive reflex. Even with no breathe-up at all, and therefore no possibility of hyperventilation, my heart rate does not decrease significantly.

From my experience, a long struggle phase does not increase my total apnea time, and the stress increases O2 consumption, decreasing the time I can safely do. I have tried CO2 training, and while it increases my CO2 tolerance and therefore improves my performance, it does not seem to produce any DR.
The drop in heart rate is the same with or without the breathe-up, so I don't think it is to blame for the lack of DR.

This means that your DR is undeveloped now, it doesn't mean that once you increase your CO2 tolerance and train your DR it won't be stronger.

Maybe I am an unusual case - I simply don't have any significant dive reflex.

No, I think that as long as you hyperventilate and work AGAINST your DR, and well, everything apnea-science & elite freedivers' experience tells us (that CO2 keeps you conscious and potentiates the DR) I don't think your claims to be an exception can be validated. (not that I think that one should accept our current knowledge base as a fact).
If you had a better CO2 tolerance then your struggle phase was easier. Maybe even easier than the one you experience now. I can assure you hypercapnic apnea can be just as fun or more, if you can handle it.
Getting that CO2 tolerance can be painful though, but working properly/hard enough can show results sometimes in a few days.
Another issue to think about is safety.

Getting cold as fast as you do does sound like an exception though. I remember it was discussed in another thread before to no avail, but I just thought of something - do you think that maybe shivering, or actually feeling cold could actually be a trained response of yours? were you always that extremely sensitive to cold water? maybe a leftover response from when you were anemic?
Have you tried training your mind to accept the feeling of cold water? to even try and enjoy it?
Being in a warm country my cold water tolerance is quite bad, but from the little experience I have I find that my mental state can affect how long I can last in cold water.

 

[naiad]

I think the shivering and feeling cold could partly be a trained response. Certainly the shivering sets in long before there could be any drop in core temperature. This morning, I had to go outside in heavy rain. I stayed out for only a few seconds, but as soon as I was back indoors, I started shivering.

I don't mind cold water outdoors as much as indoors. This is probably because it is easier to get warm in hot weather or when doing outdoor work than in an indoor pool.

I have always liked outdoor and water-related activities, so I usually approach these activities with a positive attitude, but the cold gets the better of me. Moving around keeps me warm, but as soon as I stop moving, I am unable to maintain a normal body temperature.

I don't remember always being that sensitive to the cold, which is surprising because I used to be much thinner than I am now. It started long before I started freediving, but I don't remember exactly when.

 

[BennyB]

Eat a couple more pies Lucia, that'll help!

 

[naiad]

I wish I could gain a bit of weight! rofl

About the breath-up, I think there has been a misunderstanding. I do not always do the breath-up/hyperventilation when training. In fact, I used to always train dynamic with no breath-up, and sometimes still do. Despite training a lot in this way, my performance was never very good.

 

[naiad]

One of the problems is that when I get into cold water, I get an immediate and very strong urge to breathe in. If my face is in the water, I can resist it, but it is excruciating. I can't remember any other freedivers describing this problem, but it must exist, because apparently one of the dangers of falling into cold water is that someone may lose control of their breathing and drown, even if they are a strong swimmer.

 

[atomichaggis]

One of the problems is that when I get into cold water, I get an immediate and very strong urge to breathe in. If my face is in the water, I can resist it, but it is excruciating. I can't remember any other freedivers describing this problem, but it must exist, because apparently one of the dangers of falling into cold water is that someone may lose control of their breathing and drown, even if they are a strong swimmer.

Involuntary Gasping is what happens to anyone immersed in very cold water.
I went into the fjord for a dip minus the suit in spring when the water was just above its coldest and I had to fight so hard not to inhale water, I was lucky that I had the snorkel in My gob before My head went in. Its at it worst immediately then becomes a bit more manageable as Your body adapts to it but i think there will be temperatures where You have no control whatsoever.

My Uncle who was a strong swimmer drowned in the river Clyde when it was partially frozen over. I think the cold water probably had the final say.

My cousin fell into the river Ouse a few years back in winter and He gasped uncontrollably and quite violently and He was only in up to his chest. He was lucky enough to land on a sloped bank wich held His weight. He didn't even have enough control to get Himself out and had to hauled out by a friend.

 

[naiad]

Then that is an important safety consideration for diving and other watersports.

What a useless reflex, I don't know how it could possibly be good in any situation to gasp when falling into cold water.

 

[atomichaggis]

It is rarely good to fall into really cold water.