Dive reflex not always helpful?

[naiad]

Originally Posted by Budho

It might be also a training specificity. If you train mostly dry static, you might feel discomfort during wet. I've heared friends talking about that. I feel more discomfort doing dry static and it is a bit longer.

I do train mostly dry static, so I am more used to it. I don't feel discomfort during wet static though.

Originally Posted by Ulf

In 25-28 c water the water in the suit will probably soon reach a temp of 30 c or something like that. I would assume that is way to warm to get any decent vasoconstriction. Maybe that could explain the difference in time.

When I did Sebastien Murat’s course he made us do a test to see how strong our DR was. The test went as follows, you start with checking your heart rate, then you do a FRC breath hold (without breath-up or warm-up) with your face in really cold water and check your heart rate when you get contractions. Maybe you could try that to how strong your DR is.
If your heart rate drops about 50 % you have a decent DR and if it drops 70 % you have a really good DR. If I remember correctly, he considered anything less than 50 % pretty crappy.

I usually feel a bit cold even in 25-28c water with a 5mm opencell suit.

I will do the test and post the results.

[Budho]

Originally Posted by naiad

I do train mostly dry static, so I am more used to it. I don't feel discomfort during wet static though.

I usually feel a bit cold even in 25-28c water with a 5mm opencell suit.

I will do the test and post the results.

This is what I am talking about. Water temp., face immersion,...., could have some impact on performance if you re not completely in peace with it. I doubt that diving reflex could be bad for your performance. Try to train more in the water with or without gogles and you'll see if it helps or not.
It is very strange when you try CW without the mask on, only with nose clip. It could be similar.
Aleš

[naiad]

Originally Posted by Ulf

When I did Sebastien Murat’s course he made us do a test to see how strong our DR was. The test went as follows, you start with checking your heart rate, then you do a FRC breath hold (without breath-up or warm-up) with your face in really cold water and check your heart rate when you get contractions. Maybe you could try that to how strong your DR is.
If your heart rate drops about 50 % you have a decent DR and if it drops 70 % you have a really good DR. If I remember correctly, he considered anything less than 50 % pretty crappy.

I gave that a try. There was not always any drop in heart rate, and when there was, it was very slight, not anywhere near 50%.

Maybe that explains it - I don't have any dive reflex, so the cool water only has a negative effect. It may also explain why I find FRC diving so difficult and unpleasant.

My heart rate does sometimes drop significantly during dry statics, and possibly also in wet statics. This is probably due to the pressure of air in my lungs and maybe also being relaxed.

[DeepThought]

Hmm, maybe you can tell us what is your breath-up/warm up routine?

[Budho]

Originally Posted by DeepThought

Hmm, maybe you can tell us what is your breath-up/warm up routine?

Good point!
Ales

[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]

Originally Posted by efattah

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.

Originally Posted by efattah

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]

Originally Posted by naiad

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!

[trux]

Originally Posted by adax

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

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]

Originally Posted by trux

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.

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.

Originally Posted by trux

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]

Originally Posted by 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.

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)