No dive reflex in warm water?

[FreeRestriction]

I read in a sticky that above 70 degree water your dive reflex wont activate. Is this true? If so how are people diving in warm waters doing any sort of significantly long/deep dives?

 

[growingupninja]

Don't know how others do it but chest compression (from pressure) causes some brachycardia and high CO2 causes some vasoconstriction.. Low O2 also triggers dive reflex. Temperature is just one component. I live in California and most of the year our water is could enough on the surface to trigger a dive reflex just from putting your face in. It is the one nice thing about diving in 52 degree water.

Somebody else with more experience could offer more here but I think for deep touch and go freediving, dive response is only part of it. For hanging out in deep water it gets more crucial.

The untrained 'general population' will experience some degree of DR from cold water; it's in our genes. The other aspects that trigger DR are not typically anything nondivers would ever experience, and it falls into that large area of apnea that is 'not very well studied.'

 

[FreeRestriction]

You must be up in Norcal. Down here in Socal it gets up to the low 70's on the surface. I find myself diving down just to get to cooler water so i dont over heat. Ill go down and break the seal on my wrists and neck to let cool water in. I really need like a 2mm suit for summer. (edit) i see your in LA the water dosent warm up, up there? Ive dove laguna beach in my board shorts in the summer.

Anyways thats good info thanks for the reply.

 

[x_yeti]

Maybe someone can correct me if I'm wrong (Trux maybe?) but the way I understand it:

Peripheral chemoreceptors detect lower levels of arterial oxygen - which causes peripheral vasoconstriction - which leads to bradycardia.

Facial exposure to cold water will further enhance bradycardia.

 

[growingupninja]

You must be up in Norcal. Down here in Socal it gets up to the low 70's on the surface. I find myself diving down just to get to cooler water so i dont over heat. Ill go down and break the seal on my wrists and neck to let cool water in. I really need like a 2mm suit for summer. (edit) i see your in LA the water dosent warm up, up there? Ive dove laguna beach in my board shorts in the summer.

Anyways thats good info thanks for the reply.

I live in LA. It varies but winter temps are below 60. Now it is in the 60's. We will have some days over 70 in the summer; water in the coves may be a little warmer than the bluewater on the outside. I think this year is forecast to be exceptionally warm. I have a good cold water tolerance when swimming but real apnea taxes me since I am not moving so much and if I am spearing I spend a lot of time below the surface in colder water.

 

[FreeRestriction]

I live in LA. It varies but winter temps are below 60. Now it is in the 60's. We will have some days over 70 in the summer; water in the coves may be a little warmer than the bluewater on the outside. I think this year is forecast to be exceptionally warm. I have a good cold water tolerance when swimming but real apnea taxes me since I am not moving so much and if I am spearing I spend a lot of time below the surface in colder water.

Ah i see.. Yeah for me low 60's is ideal although before i had a wetsuit i was diving in high 50's in my board shorts and other then the initial chill i had no feeling of being cold no matter how long we stayed out. Im a freakin human heat pump! Lol.

I hope it dosent warm up TOO much this summer.

Perhaps we should have the sticky corrected as it is now its missleading being it flat out states that above 70 degree water you will not get any dive reflex period. Or atleast i think thats what i read.
(edit) sorry wasnt on this forum my mistake. Still glad i brought up the question though.

 

[trux]

Diving reflex is triggered by a number of causes, some of them mentioned by Growingupninja and X_yeti. First of all, the absolute temperature is not that important, it is rather the difference of the temperature (especially on the face) before the immersion, and during the dive. Then the fact of stopping to breathe alone is already a very strong trigger for the DR which can act alone without the other contributing factors. Then it is also the depth that amplifies the effect. And then, it is primarily hypoxia (low O2) that drives the DR stronger. According to some studies hypercapnia contributes too, but there was another study denying it.

The denial of CO2 as a trigger is a bit surprising, since it contradicts the experience of many freedivers. There was an interesting information from Johan Andersson about it in this thread, but frankly told I have still doubts that hypercapnia has no influence on the vasoconstriction and hence on the DR. Since the time of the discussion I found many studies describing closer the influence of CO2 on periferal vasoconstriction, so there is apparently a conflict in all those claims. I'd like to see a new study looking at this topic closer and more critically.

Then it is also necessary to realize that the facial thermosensors do no work in the same way as a thermometer giving the brain the information about the exact ambiant temperature. They do not tell the brain there is XX degrees outside. They rather react on the loss of heat. And since water is 24 times more thermally conductive than air, as long as the water temperature is lower than your body temperature, the skin and the sensors are cooled faster in water than on air anyway.

In any case, you do not need to be afraid, there will be a diving reflex in warm water anyway, although it may be a little bit weaker than in cold water.

 

[FreeRestriction]

Great info trux and all. thanks for all of your responses.

 

[baiyoke]

In my experience, there's a big difference between a dry static, and the first wet static after beeing in a 32 degree celcius warm pool for 10-20 minutes.

During the past months I have giving instructions to people i such a pool, and when it's finally my turn, I get very relaxed quickly, and have much longer (warmup) breathholds, and much nicer ones, than when doing a dry staic. Of course being in water for 20 minutes might make me calm, and that makes a difference. BUT it FEELS like the body is allready in a different mode, just form being in water, with only a little or no facial immersion.

I BELIEVE that the/my body gets triggered from being submerged... I cannot back up the claim, but I would not be surprised if just the feeling of being in water can triggeer the dive response... After all the brain/mind often walks after the priciples of Classical conditioning (also Pavlovian conditioning or respondent conditioning).

I should add that sometimes I can feel lactic acid and/or blood shunt 10-20 seconds into my first no warmup DYN dive, wich often surprises me. So perhaps DR is easely triggered in me.

Sorry for being so totally unscientific, that's just what I experience.

 

[growingupninja]

And then, it is primarily hypoxia (low O2) that drives the DR stronger. According to some studies hypercapnia contributes too, but there was another study denying it.

The denial of CO2 as a trigger is a bit surprising, since it contradicts the experience of many freedivers. There was an interesting information from Johan Andersson about it in this thread, but frankly told I have still doubts that hypercapnia has no influence on the vasoconstriction and hence on the DR. Since the time of the discussion I found many studies describing closer the influence of CO2 on periferal vasoconstriction, so there is apparently a conflict in all those claims. I'd like to see a new study looking at this topic closer and more critically.

Yes, this surprises me. I always felt that CO2 seems to cause some sort of vasoconstriction. I am basing this off the 'sensation' and also training with my fingertip O2 meter. I will start to see the flattening in the pulse graph (indicates vasoconstriction) a very long time before my O2 is low--usually on a full lung after minute or two of dynamic work, when my O2 sat is still in the mid/low 90's. Vasoconstriction continues to increase gradually until blood O2 sat gets into the low 80's. And then it really kicks in. When I do empty lung work, low eighties is my serious brachycardia/vasoconstriction point as well. However, I must add that when I begin to experience vasoconstriction I am also experiencing contractions.

In regards to studies that show results which counter ancedotal evidence from freedivers, it might have something to do with the dive training. It's been proven that trained divers exhibit more of a dive response than the general population. Perhaps CO2 induced vasoconstriction is part of this.

I would be curious to see if people who do not experience contractions also do not experience vasoconstriction.

 

[growingupninja]

I BELIEVE that the/my body gets triggered from being submerged... I cannot back up the claim, but I would not be surprised if just the feeling of being in water can triggeer the dive response... After all the brain/mind often walks after the priciples of Classical conditioning (also Pavlovian conditioning or respondent conditioning).

I should add that sometimes I can feel lactic acid and/or blood shunt 10-20 seconds into my first no warmup DYN dive, wich often surprises me. So perhaps DR is easely triggered in me.

Sorry for being so totally unscientific, that's just what I experience.

I think if you are trained, certain aspects of dive response can be triggered mentally. You are a diver, so when you get in the water you consciously/subconsciously go into dive mode.

I have a mentally relaxed 'happy place' I like to go to before commencing a long, slow, deep dive. I don't dive with a watch or pulse meter, but on dry land using a pulse meter I noticed that when I go my diving happy place, my pulse drops and will go slightly lower than my normal resting pulse rate. Dives that start from the happy place are always my most relaxed, pleasant dives and also dives during which I feel like I experience my strongest brachycardia. People have been trained to control their pulse to some degree using biofeedback loops, I have no doubt that divers end up training themselves as well based on what 'works' for them over many hundreds of dives.

 

[growingupninja]

I read in a sticky that above 70 degree water your dive reflex wont activate. Is this true? If so how are people diving in warm waters doing any sort of significantly long/deep dives?

By the way, if you want to play around with this you can fill a bowl full of icewater, stick your face in and see what happens to your pulse (you may need a partner to read it for you), and don't try any sort of max while you are alone as you could drown if you pass out. But it is a very interesting experiment. After about 45 seconds, my pulse is usually low 30's. My dive mask cuts the decrease in half, and the response also gets reduced in proportion to the warmth of the water.

 

[FreeRestriction]

By the way, if you want to play around with this you can fill a bowl full of icewater, stick your face in and see what happens to your pulse (you may need a partner to read it for you), and don't try any sort of max while you are alone as you could drown if you pass out. But it is a very interesting experiment. After about 45 seconds, my pulse is usually low 30's. My dive mask cuts the decrease in half, and the response also gets reduced in proportion to the warmth of the water.

Interesting i might have to try this out.