• Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

Dive response, can it be improved by training?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
Interesting. Raises many new questions also, it's a little light...

One interesting thing is, that if we assume they washed out CO2 through breathing, it's clear that the body also reacts on O2 levels...
 
Yes, I don't know exactly what influence CO2 has but on dry tests when I reach certain O2 levels my pulse reacts predictably, whether or not I am on full or empty lung (full lung would be a much higher CO2 level since it takes much longer to get there).

To test whether DR responds with training would be difficult because you would need to take untrained individuals and see how they respond under apnea, and it is commonly accepted that without some training, most people cannot voluntarily hold their breath long enough to experience bradycardia. So how can you surmise what an individual's native DR is before training? This might be one way--just breathe low O2. I am also very curious as to whether cold water facial immersion is a 1:1 relationship to an individual's DR.

For instance, if training increases DR, would a diver who exhibited weak DR at the beginning of training also exhibit weak response to cold water facial immersion? And then after training that diver would exhibit a strong/fast response to cold water?
 
About bradycadia in beginners... I think most people are able to hold breath until that, because it comes allmost immediately... Do you mean vasoconstriction...?

Look at this beginner fx @ 4:00, doing neutral exhale (you won't understand the talking though )

[ame="http://vimeo.com/6431999"]Ha' det godt med fridykning on Vimeo[/ame]
 
Fascinating that a strong vasoconstriction (pulse 30) was created by low 02, not C02 and that it was trainable, at least for low 02. I get a moderate (for me) vasoconstriction long before my blood 02 level could begin to drop, so something else is also promoting it, c02? something else? It gets much stronger late in the dive when c02 is high and 02 might be beginning to drop.
 
'on dry tests when I reach certain O2 levels my pulse reacts predictably,'
Some medical training teaches that the body cannot detect a change in O2 levels. I'm not sure if that is absolutely correct or not, but anyone who has had the high altitude simulator training knows that it can be very subtle. Maybe we are only aware of the symptoms of low oxygen. Tunnel vision, hearing loss and lack of co-ordination come to mind.
 
One more comment. The CO2 detector is in the blood system, I believe, and an FRC breath hold would allow more CO2 to be stored in the lungs, especially during a static hold.
 
Have you read the posts by Fattah and the guys on apnea training? It sure seems like you can simply from anecdotal evidence. They've embedded some pretty decent peer reviewed articles as well in the thread. Like anything I'm sure the body can respond once it is trained more efficiently. Along those same lines as a evolutionarily terrestrial mammal our genetic and epigenetic window is also a limiting factor.
 
"Have you read the posts by Fattah and the guys on apnea training?"

Where are these? another website?, another thread?


Connor
 
Bill said:
an FRC breath hold would allow more CO2 to be stored in the lungs, especially during a static hold.
Click to expand...

I can't see how smaller lungs could possibly hold more CO2?

cdavis said:
I get a moderate (for me) vasoconstriction long before my blood 02 level could begin to drop, so something else is also promoting it, c02? something else?
Click to expand...

I think many, many factors combine and add to what we call DR: CO2-levels, O2-levels, lung size (exhale, especially below neutral), tactile stimulation on skin (especially below eyes and nose), temperature of water (absolute AND relative to air), stress, work response/work load etc. etc. etc...

One thing I just thought about is this: If you take a beginner under water, and he/she panics a bit, it might delay DR... So DR "training" might also include all the mental aspects, since that is a key feature of a good breathhold... My point is that "training" DR might not only be perceived as a physiological change, but a mental change also... Research into psychology have, time and time again shown, that there's no real distinction between "body" and "mind", it's one system...
 
Last edited:
Re: Re: Dive response, can it be improved by training?



I can't watch the video right now on my phone but I am not sure if that qualifies as what I meant by 'beginner'. Probably less than 1% of the general population could do a 4 minute FRC hold without a certain amount of coaching and training? And do we know what that diver's resting HR is? A drop in pulse during the initial phase of a breathhold is normal but only significant if it drops below the diver's normal resting. I do think, based on ancedotal evidence, that many people exhibit stronger/faster bradycardia with exhale work. For me I see a mild difference when dry, but with cold water there is no real difference and (probably) with gentle DYN.



Yes, all those things--vision, hearing, coordination I think can be agreed on by divers to be symptoms of low O2. In my case I am pretty sure my body is detecting it because when I reach 80-84% O2 sat on a dry static, no matter how many reps I have done, whether full/empty lung--or even if I am doing mild exercise at the time and/or begin to do more intense exercise--I experience strong bradycardia and vasoconstriction. I usually experience some degree of both sooner, and much much sooner with water. If swimming relaxed DYN after about 40-60 secs (I have worn a pulse meter with a plastic bag over it for this test) while O2 is still reading 98% I experience significant DR (30% below resting) With cold water facial immersion within 30 secs (40% below resting). Dry full lung I don't experience any DR at all for the first 2-3 minutes until O2 sat begins to drop below 98-97%. And wet warm water (above mid 60F) static my DR is identical to dry. Dry static I am much more sensitive to warm-up.
 

He he... She doesn't do 4 min. exhale, holy smoke, I think no beginner will ever do... But her puls drops fairly quickly from initial 94 to 57... Her resting heart rate is not importent I think, it's the drop when starting apnea that is, and allthough I share your concern for a bias from different factors, I don't agree it's only significant if below resting HR. A controlled experiment it needed, but it's bradycardia nonetheless (if fx a control groups HR doesn't drop) ... But I can see why you in general want to take resting HR into account, to rule out the heart just returning to resting HR because of general relaxing (and also change in bodyposition)... But the bradycardia as a more or less immediate respons to facial immersion is well established within research i'm quite sure... ( fx http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/2827/636078.pdf?sequence=1 )


growingupninja said:
I do think, based on ancedotal evidence, that many people exhibit stronger/faster bradycardia with exhale work. For me I see a mild difference when dry, but with cold water there is no real difference and (probably) with gentle DYN.
Click to expand...

Interesting. Perhaps cold water just stimulates you maximum, and exhale doesn't/can't add anything... However in general I have yet to meet anyone who doesn't respond a lot to doing exhale apnea... However I don't know about their HR/bradycardia, but I'm 99% sure it drops faster... Exhale seems to be a very effective trigger of DR... Based on my own experience, I would place it above CO2 as a DR trigger... Exhale-feeling is instant! (wich the woman in the video I linked to found out, as she pull out after 1 second, and asked for permission to inhale a little bit more...).

EDIT: Just saw the date on the paper in the link... Damn, not quite new he he
 
Last edited:
Baiyoke, if the HR doesnt drop to below resting it is not medically bradycardia or dive response related... it is just an individual ceasing the mild exertion of taking deep breaths so I think it matters a great deal!

Regarding drop in HR on exhale, I feel like ancedotally people report a fast drop in HR but without watching HR and O2 sat together it would be be hard to say if those self reported drops aren't frequently just the body responding to low O2. For instance dry, with no warm-up, I can see a drop in HR after full exhale on myself within 45- 60 seconds. But by that time my O2 numbers have also started falling. I may not experience a drop in HR for 2-3 minutes, dry, no warm-up on a full lung. But under those conditions on a full lung my O2 sat doesnt start to fall for 2-3 minutes. See? Everyone is very different and I have no doubt that partial exhale triggers something in many people, but without measuring O2 sat it could just be bradycardia from quickly dropping oxygen.

As far as cold water response I think it has been shown to vary a little bit. I would like to k ow though if the magnitude and strength of cold water response correlates directly to an individuals response when diving deep or swimming DYN. If so it would be an easy way to benchmark aspects of training.
 
growingupninja said:
Baiyoke, if the HR doesnt drop to below resting it is not medically bradycardia or dive response related...
Click to expand...

You may be right that it's not bradycardia in a strict medical sense (I don't know - but then there's no bradycardia in the old 1978 paper!) but I'd say it's definetely DR related... However since scientific papers conclude stuf like
In humans, the bradycardic response to diving varies greatly from person to person; the reduction in heart rate generally ranges from 15 to 40%, but a small proportion of healthy individuals can develop bradycardia below 20 beats/min.
Click to expand...
I'd like to think that those experiments were carefully executed in regard to medical definitions... Diving bradycardia: a mechanis... [J Cardiovasc Med (Hagerstown). 2011] - PubMed - NCBI

I just tried a very short full inhale and fairly full exhale to see when it starts: In the latter HR dropped from 47 bpm to 40 (aborted) after 18 seconds (exhale), and in the first HR went slowly up from 46 bpm to 55 until 2:00 then dropped down to 40 (aborted) at 2:30.
 
Last edited:
There is something not being considered in the bradycardia discussion. The amount of blood being pumped is dependent on pulse rate AND stroke volume. Easy to feel stroke volume declining, pulse gets harder to feel in the carotid arteries. My heart rate doesn't drop until the very end of quite long FRC dives in the pool, even though it feels like a substantial amount of blood shift is happening. But pulse gets so soft, I can't find it.

Does anyone have info on how much reduction in blood flow can be attributed to either sourse?

Connor






D
 

re: pulse rate and stroke volume... Interesting, I will try to consider stroke volume. I can see how that is important and looking at the pulse graph from a fingertip meter could be deceiving because the fingertip would be very much affected by vasoconstriction. In tests I have done on myself, vasoconstriction and bradycardia seem to be very much intertwined and while I think perhaps there have been times when vasoconstriction seemed slightly stronger than bradycardia, or at least preceded it in magnitude, I don't seem to get one without the other. Exception being the discovery of post recovery breathing bradycardia--when that happened the peaks and valleys in my graph were very deep. I gotta make time to do more tests and I will try to video some stuff to share.
 

what is your resting HR Baiyoke?
 
Well, normally if doing fitness around 50-52 (otherwise 60), but this morning it was 47, a lifetime low... (I've been doing some intens cardio lately; running or biking very close to max-puls, and just under for 4-6 minutes start to end).
 
Interesting. I know my pulse tends to run at the higher end of what would be normal for my cardio fitness level, and always has. I suspect that divers with a very low resting HR may show less of drop in pulse when in solid dive mode but it seems like numbers commonly end up in the 30's and 40's for divers, regardless of resting HR. As others have mentioned, stroke volume is certainly a consideration.
 
What is yours?

Interestingly Ulf Dextegen writes in the annotations at 9:00 in this video that his puls never drops below 50! I Was a bit surprised by that.

[ame]http://youtu.be/mOT2AbX7zbs?t=8m59s[/ame]
 
Last edited:
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…