Contractions in cold water.

[wladius]

Today, I went diving with couple of friends into a flooded quarry. Water was quite cold -- 11-12°C on the surface, 6°C on the plate at 28 meters.

I usually have quite bad feelings before the contractions start and my first contractions are very subtle and soft, but this time, while I was going down slowly, thinking I felt fine (besides feeling cold as f**k) and had plenty of time left, first contractions came out of nowhere and hit me like a train. I was so surprised I almost forgot to equalize. And I don't think I did anything unusual in my breath-up - slow triangular breathing, then 3 purge breaths - same as many times before.

Is it normal? Can cold increase/rush contractions?

 

[Penyu]

Very interesting you should ask that question. I have had the same experience a couple of days ago in a cold alpine lake (10° C on the surface). Now, I am pretty much a beginner and haven't got much experience to compare with - also, my contractions do start rather early (1:30 - 2:00) when doing static in a pool - but I was surprised that contractions started more or less immediately. I have just opened a threat on the question if these were due to the cold or maybe purely psychological, i.e. lack of open water experience and hence less than optimal relaxation. Curious to hear what other's experiences are.

 

[growingupninja]

Cold can absolutely affect the strength of contractions because the receptors on your face are triggered most strongly by cold water, although beyond a certain point (about 49F for me) colder water does not elict stronger response.

 

[MarcinB]

Ninja, although I have never experimented with really cold water, from my experience I can tell that the onset of contractions is related only to CO2 and that facial cooling does not affect it. Of course facial cooling on its own causes bradycardia and vasoconstriction. However, it is a separate reflex and in my opinion it is unlikely that it can induce contractions since it is activated within seconds after immersing the face when CO2/O2 level is normal.

During diving in cold water the face is usually already cooled before the first dive, moreover, a mask is usually worn by the diver so the effect of facial cooling is rather limited. Although I have also experienced much sooner onset of contractions while diving in cold water I would rather say that it's related to the fact that it's much harder to relax while you are cold.

 

[wladius]

When I try to hold my breath without stretching and relaxation, the unpleasant feeling comes soon. First just general discomfort, then the burning sensation in the throat and chest, and then the contractions start, first couple of contractions are very soft, almost as if I did them consciously, then they get strong.

This was something different. I was falling down and besides the cold sensation all around the body (which I was quite enjoying actually) I felt really well. I thought I had plenty of time. But the first contraction came like a punch to the chest (it might have happened around 20-22 meters) It was really surprising and I almost panicked.

I just wanted to know, if something similar happened to anyone else and if one can get over it.

 

[baiyoke]

Ninja, although I have never experimented with really cold water, from my experience I can tell that the onset of contractions is related only to CO2 and that facial cooling does not affect it. Of course facial cooling on its own causes bradycardia and vasoconstriction. However, it is a separate reflex and in my opinion it is unlikely that it can induce contractions since it is activated within seconds after immersing the face when CO2/O2 level is normal.

During diving in cold water the face is usually already cooled before the first dive, moreover, a mask is usually worn by the diver so the effect of facial cooling is rather limited. Although I have also experienced much sooner onset of contractions while diving in cold water I would rather say that it's related to the fact that it's much harder to relax while you are cold.

I honestly don't think we should treat the DR and its components as absolutes, as separete things, or as a merely physical or mental thing. It is much more likely that many known and unknown factors all contribute in different way to different parts of the DR, and some being conditioned or influenced by others. Since doctors can't really explain well what the DR consist of we should probably be very cautious about saying what causes what.

For me - the way I perceive DR - taking everything I've heard and read and felt about it tells me it's a very, very complex system of many more or less related factors, and that the mental factor is something that particularly make things relative. In time we might not be so holistic about it that we call it DR as an entity of

Saying that onset of contractions is only related to CO2 "from your experience" is of course valid as a personal experience... However cold water does powerful things to us, and it is in my view more than likely that it can trigger faster contractions for some people (for me fx), perhaps due to tensing up body or mind or both. Tension is another thing that can both rush contractions and make them strong from onset. Also exhale breathhold can create contractions considerably faster compared to full inhale, despite quite similar levels of CO2. Perhaps because of the mental aspect of not having air and the added stress, perhaps because of a more direct volume trigger... Sebastian Murat has also advocated for stress as a trigger of early and strong DR. So in my view tension (physical and mental), cold water, lung volume and probably many more things can intervene and change the time of onset and power of contractions.

Also on a more anecdotal level it is said amongst people training in cold water that it is much harder to dive really deep, and when returning to the tropics for a compitition it is much, much easier to get deep. Of course some of the reason has to do with neoprene thickness etc. but it also seems that the feeling of coldness and darkness makes it much harder to relax. But granted this does not tell us directly how that changes contraction onset and power.

Wladius perhaps you can shed some light on this topic yourself by doing reapeted statics in two different bowls of water - one lukewarm and one full of icecubes.

Theres the possibility also that the contractions are caused by other factors in the quarry than cold water, but try it out

Sometimes the cold-induced stress can turn into a very pleasant feeling suddenly, like a strong pleasant DR

 

[Penyu]

I honestly don't think we should treat the DR and its components as absolutes, as separete things, or as a merely physical or mental thing. It is much more likely that many known and unknown factors all contribute in different way to different parts of the DR, and some being conditioned or influenced by others. Since doctors can't really explain well what the DR consist of we should probably be very cautious about saying what causes what.

I think you are absolutely right with regards to the complexity of factors contributing to DR. From what I konw contractions are one sign of the onset of DR, brachycardia being the most reliable sign. For me both seem to coincide, at least when testing this lying on the sofa. I wonder though if contractions always indicate DR or if they can start independently. That would mean that the observerd early onset of contractions in cold water (due to physical or psychogical factors, or both) do not indicate an early beginning of the body conserving O2.

 

[MarcinB]

Since doctors can't really explain well what the DR consist of we should probably be very cautious about saying what causes what.

Actually this mater was a subject of a large number of studies on both humans and animals and we know quite a lot about DR and its components (of course there is still much to discover). This is one of the reasons why freediving records improve so fast. In depth knowledge of physiology really helps in this sport.

However cold water does powerful things to us, and it is in my view more than likely that it can trigger faster contractions for some people (for me fx), perhaps due to tensing up body or mind or both. Tension is another thing that can both rush contractions and make them strong from onset. Also exhale breathhold can create contractions considerably faster compared to full inhale, despite quite similar levels of CO2.

All the factors you mention above (cold, anxiety, tensed muscles) cause higher rate of CO2 production. I don't claim that there are no factors other than CO2 that affect the onset of contractions. Nevertheless, in my opinion CO2 is the most important one. If you hyperventilate contractions start later, and the more you hyperventilate the later they come. If you hold your breath on empty lungs they come much earlier because blood CO2 level rises more quickly (it's not true that CO2 level is the same as on full lungs).

Wladius perhaps you can shed some light on this topic yourself by doing reapeted statics in two different bowls of water - one lukewarm and one full of icecubes.

I did such experiment on myself as well as on about 40 students. Water temperature was ~15C. I did not observe earlier contractions during breath hold with face immersion compared to dry apnea.

 

[MarcinB]

But the first contraction came like a punch to the chest (it might have happened around 20-22 meters) It was really surprising and I almost panicked.

This was most likely so called pressure contraction. They can appear when considerable negative pressure develops in lungs. In cold water its much harder to relax so the chest is more tense and negative pressure is greater. I sometimes experience this type of contractions when I push too hard with reverse packing. In some divers (even the elite ones) they suddenly appear for the unknown reasons and can even make deep diving impossible.

 

[growingupninja]

Personally, bradycardia and vasoconstriction always go hand in hand with contractions. I may experience very mild vasoconstriction as evidenced by the EKG graph on my fingertip oxymeter before contractions when doing dry holds and on some cold water facial immersion. But never in thousands of monitored holds did I have contractions WITHOUT some degree of bradycardia or vasoconstriction, and I typically noticed a strong correlation between strength of contractions and amount of physiologically measurable DR.

Agreed, dive response and it's triggers are highly personal but for me cold water triggers contractions much sooner. I would not discount stress although our ocean is between 58 and 63f for at least 9 months per year at the surface so cold water is 'home' for me, although i am always wearing a mask. I begin to experience strong contractions within 45 secs of 50F facial immersion. Mask delays and supresses it to some degree. Dry hold or warm, non flowing water hold I may not experience contractions (or measurable DR or blood O2 drop) for a few minutes, and what I consider to be strong contractions frequently do not start until even later. I do not believe my cold water response is tied to CO2/elevated HR because when dry training low intensity hypoxic cardio, pulse and CO2 production is significantly higher than with cold water facial immersion but time to first contraction may be comparable or even longer.

 

[growingupninja]

Marcin-- 15C would be around 60F. From my own experience 60F is getting towards the upper end of my temperature only trigger, and the cold water only response was always deadened if I had dove or trained that morning.

Some literature I read claimed that water below around 55F would raise HR or not trigger HR because of pain from the cold but that was absolutely not the case with me.

 

[baiyoke]

If you hold your breath on empty lungs they come much earlier because blood CO2 level rises more quickly (it's not true that CO2 level is the same as on full lungs).

Why would blood co2 rise more quickly? Is it something you know? Or is it something you speculate? How would you explain the mechanism behind it be?

 

[growingupninja]

In my experience and the experience of guys who regularly dive FRC, CO2 production is less on exhale because the body shifts into dive mode sooner.

Also contractions come sooner on an exhale hold because blood O2 drops much faster. In myself the two are closely linked. I do get contractions from elevated CO2 but they are always milder than contractions related to low/falling O2, and the CO2 contractions are easily trainable. O2 contractions not as much.

 

[MarcinB]

Why would blood co2 rise more quickly?

If the same amount of CO2 per unit of time diffuses into lower volume of air in the lungs its level in the alveolar air and, therefore, also in the arterial blood rises more quickly. Of course this is true provided that the rate of CO2 production remains constant. However, I can't find any reason why it would be different during static breath hold on full lungs compared to empty ones. FRC diving is, however, a different story because in this case blood shift plays an important role as well.

 

[baiyoke]

If the same amount of CO2 per unit of time diffuses into lower volume of air in the lungs its level in the alveolar air and, therefore, also in the arterial blood rises more quickly. Of course this is true provided that the rate of CO2 production remains constant. However, I can't find any reason why it would be different during static breath hold on full lungs compared to empty ones. FRC diving is, however, a different story because in this case blood shift plays an important role as well.

So you are speculating. That does not even make sense even if based on your assumptions.

This is a good example of why we should be cautious about stating "facts" when talking DR and things that is not well understood. There is a thousand ways it is possible for the body to complicate the process.

Please don't state"facts" if they are assumptions. It makes it so much harder to find answers in these kind if of open discussions...

 

[baiyoke]

And btw:

During diving in cold water the face is usually already cooled before the first dive, moreover, a mask is usually worn by the diver so the effect of facial cooling is rather limited. Although I have also experienced much sooner onset of contractions while diving in cold water I would rather say that it's related to the fact that it's much harder to relax while you are cold.

This is pure speculation!

I did such experiment on myself as well as on about 40 students. Water temperature was ~15C. I did not observe earlier contractions during breath hold with face immersion compared to dry apnea.

You cannot infer anything from this about cold and contractions since you are measuring the difference between DRY apnea and wet apnea. If you want to be serious about your experiment, you need to stop making conclussions on one thing, from experiments about a totally different thing. You should keep as many factors as possible constant. The above is not telling us much because of at least two fundamentally important principles:
1) You need to control all or most other factors than what you want to assess. In the above quote you have absolutely no control about factors related to water. I relation to cold water contractions there's no experiment really and not much to infer.
2) Correlation does not imply causation. Dont jump to conclussions. Even if you did a proper experiment with warm and cold water, and even if there was no difference, you still don't know exactly why from just a single experiment.

Some very knowledgeable people on the board have previously stated some very different things compared to what you think about co2 on exhale.

Now please, I'm open for discussion, but stop putting false "facts" (hidden vague assumptions) out at that rate and so self-confident, because it is very confusing for everyone. Thanks

 

[MarcinB]

That does not even make sense even if based on your assumptions.

You claim that what I wrote doesn't make sense without giving any argument in favour of your opinion. Is this what you call a valuable contribution to discussion? Even the most knowledgeable people on the board often have to make some assumptions while discussing freediving physiology. Simple because you cannot measure many significant variables easily or at all. My assumptions are not wishful thinking, they are based on the fourteen years of my experience in the field of human physiology. I've only stated my opinion and I didn't say that anybody has to take it as an absolute truth. I can be wrong, Ninja can be wrong or even both of us can be wrong. Discussion is about exchanging opinions and arguments. You say you're open for discussion but you doesn't sound like you were.

 

[growingupninja]

I haven't done any cold water facial experiments in a couple years, i will try to do something and video the pulse oxymeter.

Dive response is highly individual.

 

[MarcinB]

Baiyoke, below is the quotation from the study by Andersson and Schagatay Eur J Appl Physiol (1998) 77: 19-24. I hope this convinces you that my statement about empty lung breath hold (static not diving) makes some sense.

"The shorter breath-holding time and easy-going phase at 60% of prone VC may be explained by a faster build-up of CO2 in the alveoli at the small lung volume, leading to a more rapidly rising arterial CO2 tension, triggering breathing movements at an earlier point."

 

[baiyoke]

Well I most certainly welcome something like that. Unfortunately I don't have access to the text, and it is not clear from the quote what it means that it "may be explained by"... If it's an ad hoc hypothesis overall, or if they know part of it; that co2 build-up faster in alveoli, and if so if they know it has an effect on the arterial CO2 tension.

Now I'm not someone who knows a lot about this stuff. But that doesn't mean I can't see when conclussions are being rushed, or understand that there can be two (or more) contradicting assumptions.

There's an assumption in your previous post relating to the quote also that the lungs can act as storagetank for offloading blod co2. This is of course true in the sense that does so, but it is relevant to look at how much co2 is stored in the lungs. Another thing; the reason it dosen't makes sense is, that it is not explained why faster build-up of CO2 in the alveoli at the small lung volume, will lead to a more rapidly rising arterial CO2 tension. But of course I would guess it is because less co2 can offload into lungs wich would make sense IF the lungs could hold a lot of co2. But take a look at these quotes from two other DB member:

Blood CO2 is always lower on an exhale STATIC (not dive) because the ratio of gas:blood is lower. Since hemoglobin can both attach O2 and CO2 then the blood has both O2 storage and CO2 buffering, whereas the lungs have strongly unequal O2 storage and CO2 storage.

and

I did not have time until now to have a look at this thread, but see there are too many wrong assumptions and claims made there, so for the future visitors I think it may be worth of clearing up at least some of them.

CO2 is lower during exhale because:
1) You start with less O2, hence you produce less CO2 (CO2 is a metabolic product of oxygenation)
2) The DR is stronger, the metabolism lower, and muscles work in anaerobic mode earlier (hence not producing CO2)
3) As Eric wrote, the ratio of the two stores lungs and blood is much lower on exhale, and because the buffer capacity of lungs is very limited, it has a great impact. Very roughly on inhale the lungs contain around half of the O2 available, while the blood contains the rest. In the same time, the lungs even at a very progressed apnea contain just a few % of the overall CO2 that is in the body. 70-80% of CO2 is in the form of bicarbonate in the red blood cells, 5-10% is dissolved in the plasma, and 5-10% is bound to hemoglobin as carbamino compounds. So while the full lungs contain around half of the O2, they can only buffer a tiny fraction of the total CO2. It means that when you decrease the lung/blood ratio by exhaling, the buffering capacity does not change much, while the production is limited (due to lower available O2 and lower metabolism). Hence the CO2 level will be lower.

Strong DR is not depending on the CO2. According to studies, CO2 does not seem to be a major DR contributor.

These parts are particularly interesting

"the blood has both O2 storage and CO2 buffering, whereas the lungs have strongly unequal O2 storage and CO2 storage."/Efattah

"So while the full lungs contain around half of the O2, they can only buffer a tiny fraction of the total CO2. It means that when you decrease the lung/blood ratio by exhaling, the buffering capacity does not change much, while the production is limited (due to lower available O2 and lower metabolism). Hence the CO2 level will be lower."/Trux

So unless you think that it is the lungs level of co2 that is the point of interest - and I remember that you don't - it seems that co2 levels can not explain the faster urge to breathe.

Another thing: Do we really know where the body measure co2-levels in relation to DR? Perhaps we do, but perhaps the picture is complex. As Growingupninja also added, O2 levels can be a trigger too, something other people have experienced.

I have some more points, I'll write again later.

Btw I think it's great you experiment and have an orientation towards papers and research, but in relation to freediving there really seems to be more unknowns than knowns, and there no need to rush conclussions