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Mammalian Diving Reflex just a Romanticism?

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tylerz

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Jun 19, 2002
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Has there been any research that actually compares the Bradycardia and Vasoconstriction associated with diving, to the Bradycardia and Vasoconstriction associated outside of diving (dry apnea)?

There is much reference to the mammalian diving reflex occuring due to water pressure and water temperatures. However, one can clearly see bradycardia occuring just by holding one's breath dry. I believe, as well, vasoconstriction occurs under these conditions when one stays relaxed (there are ways of hindering vasoconstriction as well). Therefore it would seem the only mammalian diving reflex that occurs mainly due to water, would be blood shifts.

It is quite possible that the water accelerates or increases these (bradycardia and vasoconstriction) symptoms of apnea, but it just seems misleading to associate the symptoms of apnea with water in an educational sense. Of course one can say apnea and the bodies response to it, are strongly related to the bodies evolution and association with diving from a time when that was relevant to our activity. But that does not change the details of its workings.

I wonder if we have not found a simple explanation and therefore focused on the wrong area for the foundational triggers of mammalian diving reflexes. Of course it is very romantic to imply that only those who dive experience mammalian diving reflex, which is probably very misleading.

So this probing and exploration is intended to determine whether this is a truthful statement:

"it just seems misleading to associate the symptoms of apnea with water, from an educational sense"


Cheers,

Tyler
 

efattah

Well-Known Member
Mar 2, 2001
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Perhaps we should identify two or three reflexes:

1. Mammalian apnea reflex = MAR
2. Mammalian immersion reflex = MIR
3. Mammalian [thoracic] negative pressure reflex (occuring when the lungs collapse at depth) = MNPR



Eric Fattah
BC, Canada
 
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donmoore

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I personally do not think it is romanticizing or misleading. I believe the definition is the adaptation to water that our bodies undertake when we are in water, which already means the acceleration or increase over what happens out of the water. It is so significant that it needs definition. You can state that bradycardia and maybe even a little vasoconstriction occurs from holding ones breath on land, but the amount they occur is clearly less than what happens in water. Experienced freedivers heart rates can slow down to 20 beats a minute at depth. This is far slower than they experience when doing dry statics.

Blood shunt is probably also helped by water pressure pushing blood out of the extremities. I believe it has been shown in scientific studies to be very large which would make it not even comparable to what happens in a dry land breathhold.

Most freedivers have practice dry land as well as wet statics. They are fit and in tune to their bodies and can easily notice when their performance increases or decreases. Many have reported significantly better times on land, just by submerging their face in a container of water before they start.

I like how Eric broke it up. Reflex from breathholding, reflex from immersion, and reflex from depth.

Interesting topic,
don
:)
 

donmoore

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Aug 19, 2002
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I’m sorry you asked if there was any research. Here are a few that might have useful information.

Arnold RW (1985) Extremes in human breath-hold, facial immersion bradycardia Undersea Biomed Res

Bejertnaes L, Hange A, Kjekshus J, Soyland E (1984) Cariovascular responses to face immersion and apnea during steady-state muscles exercise. Acta Physiol Scand

Bonneau A Friemel F, Lapierre D (1989) Electrocardiographic aspects of skin diving Eur J Appl Physiol

Butler PJ, Woakes AJ (1987) Heart rate in humans during underwater swimming with and without breath-hold.

Cambell LB, Gooden BA, Horowith JD (1969) Cardiovascular responses to partial and total immersion in man J Physiol (Lond)

Chang LP, Lundgren CEG (1996) Maximal breath-holding time and immediate tissue CO2 storage capacity during exercise and while breatholding through an added resistance J Physiol

There are many more. As you can see the mammalian diving reflex is well studied.
don
:cool:
 

fpernett

Well-Known Member
Nov 7, 2001
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Interesting discussion.
I also believe that bradycardia is induced with breath-holding, and the response is stronger with training. But the immersion and cold water maximize the reflex.
This reflex occurs even in exercise (also dry exercise).
Here is another paper on this subject:

Butler PJ, Woakes AJ. Heart rate in humans during underwater swimming with and without breath-hold. Respir Physiol 1987; 69:387-99

Sterba JA, Lundgren CE. Breath-hold duration in man and the diving response induced by face immersion. Undersea Biomed Res 1988; 15:361-75

Tipton M. The effect of clothing on "diving bradycardia" in man during submersion in cold water. Eur J Appl Physiol Occup Physiol 1989; 59:360-4

Ferrigno M, Grassi B, Ferretti G, et al. Electrocardiogram during deep breath-hold dives by elite divers. Undersea Biomed Res 1991; 18:81-91

Ferrigno M, Ferretti G, Ellis A, et al. Cardiovascular changes during deep breath-hold dives in a pressure chamber. J Appl Physiol 1997; 83:1282-90

Delapille P, Verin E, Tourny Chollet C, Pasquis P. Heart rate variation after breath hold diving with different underwater swimming velocities. J Sports Med Phys Fitness 2002; 42:79-82

Hiebert SM, Burch E. Simulated human diving and heart rate: making the most of the diving response as a laboratory exercise. Adv Physiol Educ 2003; 27:130-45

If we remember the Pavlov experiment, it's possible that when we hold our breath, our body "think" that we are diving and set the diving reflex. Very hard to find out. Maybe all humans beings have this reflex deep in their genoma. In that way it will be a diving reflex.
 
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Paul Kotik

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Oct 21, 2003
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NON ROMANTIC MDR

I'd be interested in seeing the behavior of a system with the physical characteristcs of a human circulatory system, but without any sort of homeostatic mission. For example, as simple electric water pump driving water through a network of flexible tubes. The pump piston drive, let's say, by a belt drive that allows for slippage when the resistance encountered by the piston increases.

It would be interesting to see what would happen if we got this little system happily pumping away, then grdually submerged it to increasing depth. I think that we would observe a) a tendencey for the tubes most distant form the pump to constrict and collapse before those closest to the pump, and b) a reduction in the number of the piston's strokes per minute, as the belt begins to slip.

In other words, perhaps bradycardia and blood shunt are 'dumb' consequences of a physical system rather than 'smart' or adaptive responses of a homeostatic, physiological system.
 

Paul Kotik

FreeDiving Editor
Oct 21, 2003
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NON ROMANTIC MDR

I'd be interested in seeing the behavior of a system with the physical characteristcs of a human circulatory system, but without any sort of homeostatic mission. For example, as simple electric water pump driving water through a network of flexible tubes. The pump piston drive, let's say, by a belt drive that allows for slippage when the resistance encountered by the piston increases.

It would be interesting to see what would happen if we got this little system happily pumping away, then grdually submerged it to increasing depth. I think that we would observe a) a tendencey for the tubes most distant form the pump to constrict and collapse before those closest to the pump, and b) a reduction in the number of the piston's strokes per minute, as the belt begins to slip.

In other words, perhaps bradycardia and blood shunt are 'dumb' consequences of a physical system rather than 'smart' or adaptive responses of a homeostatic, physiological system.
 

tylerz

Well-Known Member
Jun 19, 2002
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Great replies guys!

I have a long quote from one of the articles:
"Severe hypoxemiaduring apnea in humans: influence of cardiovascular responses" - by Peter Lindholm

"The diving response (in some literature referred to as the diving reflex) is a combination of vasoconstriction and bradycardia and has been studied in both humans and other animals. It is mainly elicited by the repiratory arrest per se, but is also influenced by multitude of other factors such as face immersion, hypoxemia, and hypercapnia (Hong 1987; Manley 1990). The basic response pattern is similar regardless of whether apnea is done in dry conditions or the subject immerses the upper part of the face in water during apena (Stromme et al. 1970; Manley 1990)."

This is what I suspected we would find. The key point is that "...mainly elicited by the respiratory arrest...". This is where I find the majority of diving related references (ie freediver references) misleading, since they generally present the opposite. I personally believed the majority of the response was due to apnea. This being supplemented by my "experience" and being a person who has in the past practiced a LOT of dry statics and dry apnea exercise.

So based on these findings, what do you guys think about whether the current impressions/suggestions/statements are misleading? I personally seem to hear a lot of statements saying the opposite to these findings!

Cheers,

Tyler
 

tylerz

Well-Known Member
Jun 19, 2002
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Hopefully, it was clear in my post that I was not just looking for a plethora of "Mammalian Diving Reflex" studies, that confirm the extreme response of bardycardia and vasoconstriction while diving. That is obvious to me and experienced as well. The subject of the thread is maybe misleading (just wanted to get your attention ;))

The content of my post was attempting to specify that I was looking for studies of the DIFFERENCE between wet and dry. Which requires a very strict environment to test. Especially since many people do not find dry apnea very comfortable. Given the wrong people you could have comfort strongly influencing the results of such a study, just as we find occurs in comparing training vs competition.

Just want to clarify that so we do not get a flood of references that make people think the thread is complete and understood, by confirming the existence of mammalian diving reflex.

Cheers,

Tyler
 

tylerz

Well-Known Member
Jun 19, 2002
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Eric - wonderful idea.

Donmoore - I agree with the MDR definition in general. Where you say it is "so significant", I think that is the VERY subjective area I wanted to bring out. My response here is going to be inconsiderate of what I have just previously posted regarding the findings.

I have found that I can reduce my heart-rate from 55-65bpm at rest to around 30bpm without even a max attempt at dry breath-hold (<5min). When my grandfather was in the hospital I decided to amuse them by grabbing the pulse oximeter and breath-holding without a breath-up. They watched as a few seconds later my heart-rate sank from 65 to 43bpm. If I ever had a pulse oximeter present while doing a max breath-hold, I am sure you would see my heart-rate in the 20bpm range. So I would suggest your speculation of water being the strong influence, is misdirected.

In a previous post of mine, in this thread, I state a plausible reason for the lack of experienced freedivers being in tune with the difference between dry and wet. Yes, many of them have done dry statics, but few of them continue to do them regularly to the point that they are just as comfortable doing wet and dry. I have to ensure I have a low temperature in the room, wear no clothes on my upper body, support my knees with cushioning, and prop my head, for best results when doing dry statics.

As another study demonstrated, if the subjects were pestered while doing apnea in water, the bradycardia and vasoconstriction did not occur. I think this supports the idea that they are very dependent on relaxation. Therefore it makes sense that the average person doing dry statics, not being relaxed, is not going to have the same response as floating weightless and cool in water.

So I think it is weighing much more in favor of a combination of apnea and relaxation. Probably also the reason I sense that I can induce vasoconstriction even prior to starting a dry breath-hold.

Hope that clarifies why I would differ in belief to some of your ideas expressed here.

Thanks for your ideas and references so far... yes, I hoped this would be an interesting thread ;)

Frank Pernet - Yes, in general I get the feeling that most people feel apnea responses are the bodies association with aquatic apnea. This would also be interesting to explore whether there are reasonable land benefits to these responses. There is a possibility the body is "thinking" of some other activity that has nothing to do with water. We need Sherlock Holmes. Anyhow, I as well feel the strongest likelihood of the existence of the responses are a "diving reflex". However, little 6 year-old boy on the swings, holding his breath, may also get these reflexes and might be confused if we tell him he was "diving". ;)

Paul Kotik - I also have been speculating on this. I wonder if the reason for not getting vasoconstriction sometimes is directly proportional to the heart-rate and strength. It would seem like if the heart-rate slows down then vasoconstriction can occur more easily due to the longer time (time between heart beats) for the vessels to settle into a tighter constriction. If they have this time, then further pulses of blood would be impeded. Yet if the heart-rate stayed high, then everytime the vessels began constricting, they would be interrupted as blood with enough pressure overcomes the initial constriction forcing the vessels open again. This could explain how there is variance in vasoconstriction, even if what you suggest is correct.


Thanks again guys. Gals?

Tyler
 

cebaztian

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Oct 3, 2003
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THE DIVING RESPONSE

This is what I have learnt:

1) Bradycardia -Drop in pulse
2) Anaerobic metabolism - Cells ability to function without oxygen
3) Vasoconstriction - Bloodvessels shrink. Bloodstream directed away from limbs for the benefit of heart, lungs and brain.
4) Splenic contraction - Releasing red blood cells carrying oxygen
5) CO2 tolerance - After repeated breatholds
6) Higher blood pressure - To "compensate" lower heart rate and less stroke volume.
7) Less stroke volume in heart - To "compensate" vasoconstriction.


But why it happens is a more intresting question...

Sebastian / Sweden
 

fpernett

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Nov 7, 2001
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I understand your point tyler.
The only way to know is to find a culture that "never" had contact with the water, and never had "intimal contact" with other culture that do. And see how they respond to apnea.
There is a post elsewhere, where a freediver said that his HR is around 130 while he's in static apnea. That's in contradiction with the "diving reflex".
I think there are more experiments to do, to find the real answer.
 

donmoore

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Aug 19, 2002
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Tyler,
Interesting discussion and thanks for clarifying. I too am very curious to what happens on my breathhold when attached to an Oxymeter. So much that I order one for me for Christmas. I haven’t told my wife yet – still thinking about the best way to tell her I spend $305 for a gift for myself:confused:

From everything I have heard, and also playing with an oxymeter in the hospital myself just 2 weeks ago when I had a surgery, I don’t think your heart rate will drop into the 20 in a dry static with a resting heart beat of 55 bpm. What I have heard, and have a little experience with, is the rate will drop 10 – 15% in the first minute and after that it will slowly rise to where it will eventually be higher than resting. I bet Eric F. has some good info on this.

Check out MaxDream heart rates in the “What's your static PB?” http://forums.deeperblue.net/showthread.php?postid=312050#post312050 . This is a very interesting subject, because I have a low heart rate, 49 bpm resting when they took my vitals before surgery 2 weeks ago, but my PB is only 6:00. MaxDream is getting into the 7’s with a very fast heart rate.

Let me know what your heart rate is during a hold when you get to take it.
don
 

Ben Gowland

Aplysia gowlandicus
Apr 4, 2002
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Logic and my own freaky experiences

As a scientist and freediver, I'm always very weary of the studies on mammalian diving reflexes for the very reason pointed out above - it only seems to work properly when you are fully relaxed. I have never seen that 'factoid' taken into account in the research that I have read.

1 point to add to the discussions: The differnce between a reflex and a reaction. Alun and I had a discussion about this:

The term reflex should be reserved for an event which triggers a neurological or endocrinological response. If the 'reflex' is not 'controlled' by the body, and is a mere reaction/effect of pressure, then we decided that reaction was a better term. This kind of relates to what Eric F and Paul K were saying:

Apneic reflex seems to be partly a mixture of both nervous reflex and mechanical reaction.

Immersion reflex is certainly a mixture of both.

the reaction to depth seems primarily a 'reaction' - more along the lines of Paul K's 'bags 'n' tubes' concept, than the body ' sensing' depth/pressure.

As a matter of physiology - reference is often found to 'baroreceptors' in the body, but these are not sense true hydrostatic pressure sensors, but sense stretching of certain membranes. The reason this is important is because it should be remembered that the body does not react to absolute pressure (until the pressure gets v. high and membranes start acting differently), but reacts to pressure differentials which is what happens at depth when the lungs compress and there is a slight pressure differential between the body and the thoracic cavity. I ramble on......

Anyway - my own freaky experiences:

On land I can lower my heart rate from resting (~45) down to sub 30 within a few beats and hold it there for 10 secs or so...all by taking advantage of pressure differentials. I'm sure others here will have observed their own HRs decrease when doing the same.

My HR usually goes up when holding my breath on land and then drops after about a minute to ~40. In water a similar response happens, but slightly lower. At depths of less than 20m I have measured my HR down to ~20 bpm (occassionally).
 

tylerz

Well-Known Member
Jun 19, 2002
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Re: Donmoore's post

Haha... Yes there are too many toys one can buy once they get interested in what is behind this diving stuff! ;) I have been wanting to get an oxymeter as well. Keep us posted on results once you get yours!

As far as the rest heart rate dropping by 15% before slowly increasing... I so far have not experienced that. Generally what happens for myself is that my heart rate jumps up probably to 70bpm for the first 30-60secs. This is followed by a gradual decline back to my resting heart-rate, over another 1-2 minute period.

I get contractions, depending on breath-up and body "mood", between 3:00-4:30. Just prior and into the contractions my heart-rate begins to slow down rapidly. I have never followed it to the end but have at least witnessed the continual decline for another 2-3 minutes. This putting the heart-rate to 32bpm. 55-32=24. 24bpm is a drop of 44%. That is 3x what you have heard! I have done one breath-hold to 8+ min and many in 7+min.

At the end it would be interesting to see when/if my heart-rate eventually increases while still performing the static. But my prediction is that for a 7+min static, I probably would see the heart-rate drop to the mid/high 20bpm's around 6-6:30.

I can definately not be sure my body response and workings are similar to the average, but at least it suggests that maybe we have not narrowed it down yet with such variances in individual responses. As you and Frank pointed out about the guy with the crazy BPM doing 7+min statics. I was following that thread off and on as well. Ya I do not know what to say about that guy, other than the body has a way of varying the workings of the body and compensating for the effects of these variations.
 

tylerz

Well-Known Member
Jun 19, 2002
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pressure differentials

Ben,

Great post and differentiations for clarity.

By what means do you influence pressure differentials on land?

On your dives to 20m where you measured low BPM did you swim to 20m or use sled/weight for a "free" ride? I wonder if the fact that the body is exerted at the beginning of a dive, assists a more rapid decrease in heart-rate, or adversely affects it.
 

Bill

Baron of Breathold
Oct 17, 2001
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Tyler
Thanks for the article. I've wondered about that because my variable resting heart rate doesn't seem to affect my statics the way it affects my aerobic ability.
My pulse rate pattern is very close to yours but the pulse doesn't get below 45 except briefly. It is a lot different in the water. I did more than fifty 7s this year. All but one were dry.
Happy Holidays
Bill
 
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