Harsh vs. gentle CO2 table

[Drowned Fish]

Hi!

Having completed AIDA** and *** av We Freedive in Phuket I find it due time to find what kind of training methods are working for me. For pool training my first priority is buffing my CO2 tolerance, because I've come to realize it sucks as it is (although not exclusively CO2 training).

I like to keep things simple and has set up a CO2 table of ten 25m laps with two breaths in between each lap. For me it's a really harsh table, but I'm able to complete it, and it feels so good afterwards. Doing a static until first contraction and immediately after doing a 75m DYN after this table is ridiculously easy. Low CO2 discomfort, but of course with decent lactic burn.

How do others in here prefer their CO2 tables? Slow-rising and long or rapid-rising and short? Or both? Or something in between?

What are the pros/cons of a steep vs a gentle-sloped table (if there are any practical difference). Only after finishing the 3* I fully realize how many nuances there is of every aspect of freediving. I'm in for a good study before doing the 4* next year.

Ronny

 

[Kars]

Interesting questions.

My short answer is that my main consideration is endurance, can I endure the training for weeks on end, or is it wearing me out and turning my love into a tiresome routine.

I don't mind doing some challenging steep schedule, but I find starting modestly, allowing my mind and body adjust more pleasurable and educational.

Congratulations on your 2 and 3*, I think your broader view and considerations are one of the best fruits you harvested.

Question, is your legburn less, more or equal compared to a normal preparation 75m?
In other words do you experience more, the same or less dive reflex (MDR)?

 

[Drowned Fish]

Endurance is not to be neglected, yeah. I didn't think at that scale. Perhaps differing a bit could do good. Perhaps a three week cycle with one week really steep ones, one week with really really gentle ones to "recover" from the week before and one week steeper, but still not very challenging, to "warm up" for the tough week. I think I'll try something like that and experiment a bit on the larger scale to find what fits my head.

About my leg burn, I can't say very precisely. As I yet haven't begun training seriously because of lack of buddy I have never done more than 50m with regular preparation (and had never felt significant lactic burns before the STA+75m), but I do know that the at the STA+75 the MDR kicked in a short while after beginning the DYN, but I suspect that the onset were earlier than usual because I did the CO2 table 10 minutes before. At 50m DYN I've barely felt the MDR kick in before reaching the 50m mark.

I guess I'll get better perspectives in the coming month or so when I'll be able to set up and (safely) do a real training program.

Thanks on the congratulations. The broader view is definately something that has come as a direct result of the courses, but for me I believe the greatest leap has come from Richard and Sarah at We Freedive because of the way they made me really want to dig deeper in everything. Physiology, technique, passion and everything. Great instructors and fantastic persons.

 

[Rik]

If an CO2 table, or any table, is to steep, it might look like a challenge, but it is also hard on the grey matter. You might risk an "burn-out" especially if you train often.

My experience is that all carbon tables become more interesting if you try to avoid to hyperventilate in between. Even an "light" table can become heavy enough to give improvement, but not so much challenging that you would burn precious willpower.

 

[Drowned Fish]

Rik, that's exactly what I wish to avoid. So I've realized that only doing tough monster tables is no good in the long run. Actually, thinking about it I might as well skip the steeps considering I play UW rugby once or twice a week, which I would consider pretty tough on the CO2.

A light table will - given more laps/time - build the CO2 to whichever level I can stand, but because it's sloping so slowly it might be easier to handle? Tryers gonna try!

Another question; approximately how many breaths is needed per 25m lap to guarantee good oxygen saturation "indefinately"? I suspect that one exhale and inhale might be on the border of negative net balance per lap, but as the Bohr Effect kicks in theoretically might keep the saturation on the safe side. Does that sound reasonable? Of course it depends a lot on technique, lung volume etc etc.

 

[Rik]

I don't have the numbers about how fast you would get normal saturation, although that is one to add to my lists of experiments I would like to do.

While one breath seems to be enough for static, I would not personally expect the same for dynamics, because you would expect to build some oxygen debt, especially when experiencing lactate acid build-up, and you want to be able to keep your diving technique on track.

I would personally go for at least two breaths, but I am curious to hear other opinions.

 

[Drowned Fish]

Oxygen debt is a concern I agree. Because of the practical issues it's more of a theoretical question than a practical. I can't see any benefits of pushing so hard other than to induce the mother of all CO2 headaches.

If your legs (theoretically) can work indefinately in a fully anaerobic state I believe that one breath is way more than enough. After a couple of laps the MDR would have kicked in permanently and in full force, and in that regard the oxygen debt will not be paid until the end of the table because of the vasoconstriction preventing blood flow to your now very lactic legs. And the Boohr Effect will greatly help the CO2 extraction.

A little bit off topic: Maybe - directly opposed to hyperventilation - building up very high levels of CO2 (with optimal oxygen saturation. Should be possible with the "correct" breathing technique) before a record attempt can give good results? Has it been tried? Of course that would require very high CO2 tolerance, but logically the side-effects could be a full-blown MDR even before starting, and a greater effect of the Bohr Effect.

 

[Simos]

Don't think that starting with a high CO2 for record attempts would be a good idea - I'd say the opposite; if you have huge lungs and going for a record attempt, you provably need to start with pretty low CO2..

However without being able to explain it scientifically I think there is a merit in what you are saying if done differently ie doing lots of successive practice holds and building CO2 that way, then getting rid of it just before your max attempt.

 

[trux]

Don't think that starting with a high CO2 for record attempts would be a good idea - I'd say the opposite; if you have huge lungs and going for a record attempt, you provably need to start with pretty low CO2..

No, not really. The higher CO2, the deeper you can push into hypoxia without the risk of a blackout (due to the shifted Bohr effect), hence from the point of view of the maximal performance it would be indeed interesting having high level of CO2 in the blood.

Unfortunately the Bohr effect is a double edge sword - while the shifted effect (due to high CO2 level) helps discharging O2 from hemoglobin even at progresses hypoxia, in the same time you will not manage to saturate hemoglobin if you keep high CO2 before the start of the breath-hold. It means you will start with lower volume of oxygen in the blood (and especially in the venous blood), which will of course penalize the performance. It means you need to find the perfect balance where you manage to saturate the blood as much as possible, while keeping enough of CO2 to keep you conscious when in hypoxia.

 

[Kars]

For my max dives, very slow and light low belly breathing (near 'empty' to 1/2 full is how how I would typify it). A Yogi would say short breathing, indicating the low airspeed not moving a piece of tinfoil hanging close (short distance) from their airways.

The final breath is a bit deeper out, and slowly fully in, followed by some packs.

My Total lungvolume is 6,5L and I weigh about 73KG, 187cm tall.

 

[Simos]

No, not really. The higher CO2, the deeper you can push into hypoxia without the risk of a blackout (due to the shifted Bohr effect), hence from the point of view of the maximal performance it would be indeed interesting having high level of CO2 in the blood.

Unfortunately the Bohr effect is a double edge sword - while the shifted effect (due to high CO2 level) helps discharging O2 from hemoglobin even at progresses hypoxia, in the same time you will not manage to saturate hemoglobin if you keep high CO2 before the start of the breath-hold. It means you will start with lower volume of oxygen in the blood (and especially in the venous blood), which will of course penalize the performance. It means you need to find the perfect balance where you manage to saturate the blood as much as possible, while keeping enough of CO2 to keep you conscious when in hypoxia.

I was referring more to the fact that someone with big lung volume would probably struggle a lot due to lactic if they started loaded with CO2 Trux and also even if having a long static you'd be talking some serious CO2 load at the end - I guess one could train to stand that but still... I know I wouldn't want to start with more CO2 than I had to

Also very true about Bohr effect - you wouldn't benefit from high CO2 in the beginning as far as O2 saturation goes, you are better off raising CO2 during the hold

 

[trux]

I was referring more to the fact that someone with big lung volume would probably struggle a lot due to lactic if they started loaded with CO2 Trux and also even if having a long static you'd be talking some serious CO2 load at the end - I guess one could train to stand that but still...

I'd tell you better struggle with high CO2 than blacking out.

Also very true about Bohr effect - you wouldn't benefit from high CO2 in the beginning as far as O2 saturation goes, you are better off raising CO2 during the hold

It is not at the beginning of the breath-hold, that the low Hb-O2 affinity would matter, but before the breath-hold. However, the rate of CO2 production during the static breathold is proportional to O2 consumption, so you want to keep the CO2 production as low as possible, of course too. Hence it is indeed better to start with high CO2, while keeping the maximal possible O2 saturation as well. Unfortunately one goes against the other, so a compromise is necessary.

 

[Simos]

I'd tell you better struggle with high CO2 than blacking out.

It is not at the beginning of the breath-hold, that the low Hb-O2 affinity would matter, but before the breath-hold. However, the rate of CO2 production during the static breathold is proportional to O2 consumption, so you want to keep the CO2 production as low as possible, of course too. Hence it is indeed better to start with high CO2, while keeping the maximal possible O2 saturation as well. Unfortunately one goes against the other, so a compromise is necessary.

It depends on the profile of CO2 production during the hold but I still seriously doubt that you are better off sacrificing O2 saturation at the start (pre-dive) in order to have lower Hb-O2 affinity during the hold.

This would imply that even if you don't HV you will eventually black out while still have significant O2 that has not been released but while I dont have data at hand, I doubt it would be the case.

I think you'd be overall better off focusing your training to withstand low O2 without blacking out and starting with normal or even lower CO2 levels (more O2 saturation) - by the end of the hold CO2 should be high anyway and the Bohr effect will work to your favour when you need the O2 the most...

Is there any competing at high level that starts with higher CO2 than normal out of curiosity?

By the way - I think CO2 level will make no difference at all to whether you black out or not. Blacking out in most cases is due to how much you are determined to push things - high CO2 or not, it's quite simple: if you push enough you will eventually black out, it's just a question of when

 

[Erki]

Not sure that high CO2 before dive can reduce your pre-dive saturation. At least on the common grapths there is almost complete saturation at 100 mm/Hg of O2 even in the presensce of Bohr efect.

I'm not a top diver, but I do have a clear benefit when starting with moderately high CO2 level.

 

[trux]

By the way - I think CO2 level will make no difference at all to whether you black out or not. Blacking out in most cases is due to how much you are determined to push things - high CO2 or not, it's quite simple: if you push enough you will eventually black out, it's just a question of when

No, Simos, you have it wrong. CO2 has a very deciding influence on the breakpoint of the blackout. With high CO2 it is not only harder to get over the threashold, but physically you will blackout at much deeper hypoxia than with low CO2.

The more CO2 you have from the beginning, the better. Of course, as I wrote, it is difficult to have both high CO2, and high SvO2 (venous O2 saturation) in the same time, so a reasonable compromise needs to be looked for.

Not sure that high CO2 before dive can reduce your pre-dive saturation. At least on the common grapths there is almost complete saturation at 100 mm/Hg of O2 even in the presensce of Bohr efect.

Bohr effect is always present, the curve only shifts left or right. It is true that the saturation of arterial blood (SaO2) differs rather little (~95%-99% at rest), but the same cannot be told about venous blood (which represents 2/3 of the blood volume) - the saturation is strongly dependent on the Hb-O2 affinity.

 

[Simos]

No, Simos, you have it wrong. CO2 has a very deciding influence on the breakpoint of the blackout. With high CO2 it is not only harder to get over the threashold, but physically you will blackout at much deeper hypoxia than with low CO2.

The more CO2 you have from the beginning, the better. Of course, as I wrote, it is difficult to have both high CO2, and high SvO2 (venous O2 saturation) in the same time, so a reasonable compromise needs to be looked for.

Sorry Trux of course you are right; it does make a difference as well as many other factors - I was just half-joking about the fact that whether or not you blackout on an attempt is mainly a question of how much you will push yourself. And if you think about it, blacking out at deeper hypoxia is more dangerous than blacking out at less hypoxia...

The point i was trying to make was that if you are pushing things to the point where you need to start playing with CO2 levels at the start to keep you from blacking out you are probably on thin ice anyway and sooner or later, you will get a blackout regardless.

Of course for competitive freediving at high level pushing to the limit cannot be avoided (or is the point I guess) but for all other types of freediving, I'd question the need to push that hard. At the end of the day, you will get to A number/time...

One advantage I see in training to start with higher CO2 than normal is that at a comp or other situation when you'll probably be stressed and HV from anxiety a bit you might end up with a normal CO2 level anyway

 

[trux]

Sorry Trux of course you are right; it does make a difference as well as many other factors - I was just half-joking about the fact that whether or not you blackout on an attempt is mainly a question of how much you will push yourself.

But even that is not true. With low CO2 you will blackout easily without any struggling at all, without even seing it coming, while with high CO2 it will be significantly harder to come into the unsafe zone.

And if you think about it, blacking out at deeper hypoxia is more dangerous than blacking out at less hypoxia...

Sounds logical, but actually with low CO2 the low hypoxia is as dangerous as the high hypoxia at high CO2. Actually the curve of the progressing hypoxia at low CO2 may be steeper, and you can get farther into anoxia after the BO, than it would be at high CO2.

The point i was trying to make was that if you are pushing things to the point where you need to start playing with CO2 levels at the start to keep you from blacking out you are probably on thin ice anyway and sooner or later, you will get a blackout regardless.

Yes, you can't exclude the BO, but when hyperventilating, the BO is many folds more likely. The problems is also that when a freediver learns a hyperventilating -pattern breath-up, once he finds himself in a stressful situation, the body starts hyperventilating automaitcally (and that can be even several hours long), the body gets rid of significant amount of CO2, and a premature BO is preprogrammed.

The point is rather to find breath-up that maximizes the O2 stores, while preserving CO2 levels as much as possible. It is doubtfull it would be above the normal CO2 level, but if it were possible, it would help maximizing the performance.

 

[Drowned Fish]

This discussion escalated a somewhat beyond my paygrade, but I can understand the points being made. I'm just about as much a beginner in freediving now as I were in engineering a couple of years ago, but I found the theoretical implications of starting with higher CO2 interesting.

I've heard that many high level freedivers are able to induce the MDR even before started. Is that true or a semi-truth? I've "learned" that the most important trigger for MDR is the CO2 levels, something I kind of confirmed yesterday.

I did a dry CO2 table walking casually for 30 seconds, doing one full exhale-inhale, walking 30 seconds etc. Lap 4-6 were the worst with respect to CO2 levels, but then the MDR kicked in. I felt blood surging from my arms and legs, and sounds got somewhat "muffled". After that the CO2 production must have dropped significantly, because the CO2 discomfort dropped to just a bit uncomfortable, and I couldn't detect elevating CO2 levels during the last 7-8 minutes, at which point my legs tired. In a pure unscientific way, I would say that the CO2 production/O2 consumption must have dropped by 50% after the MDR had kicked fully in compared to the beginning. Very interesting. I would really love to find an "easy" way to begin a dive with full O2 saturation and full MRD. I don't know at this point how much O2 I'm wasting before the MDR kicks in, but it's a lot!

 

[Simos]

I am only a beginner too but I did have moderate success (for my own standards) with a series of successive holds leading up to the max attempt. I believe the build up of high CO2 prior to the max attempt was the key.

I think there's mileage in this concept but it is unfortunately very time consuming. If I remember correctly some top freedivers like Herbert was using something similar for his static attempts so it does work at a high level too.

There is of course the 'no warmup' camp too but I think it's the kind of thing that takes a lot of getting used to...

Another thing that might help is cold water and no mask..

 

[Drowned Fish]

[x] Cold water (in Norway)
[x] Fluid goggles
[ ] Buddy for training

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