physiological reactions while holding your breath

[upp3rd0g]

Hi all,

I am new to the site. Allthough I am into recreational scubadiving I arrived on this forum for another reason.

I am trying to find out what happens in the human body when you hold your breath.

Could anybody point me to some scientific/medical explanations on the internet? Or possibly give some keywords which help me in exploring this topic further?

I ask this question here as I assume that freedivers know this topic very well.

Cheers.

Marco

 

[efattah]

This is a complicated question. It is answered across dozens of posts in this forum, and in papers as well. But there is no definitive list of these posts or papers.

 

[upp3rd0g]

Thank you for your reply. Would you be able to give some keywords or example posts? I am new to this topic so I am having a hard time finding these posts.

 

[efattah]

Basic stuff when holding your breath:
- Heart rate rises initially, then drops gradually throughout (bradycardia)
- Blood vessels in the arms and legs constrict (vasoconstriction), to pool blood for brain/heart, where it is needed
- CO2 levels increase, which trigger defense mechanisms
- CO2 eventually causes involuntary abdominal contractions (usually just termed contractions), which increase blood flow to the brain
- Elevated CO2 levels cause oxygen to be more easily released from the blood (Bohr effect)
- When arterial blood oxygen saturation (SaO2) drops below around 30% (in elite divers), a blackout occurs (BO for short, or 'samba' which means hypoxic seizure)
- If exercising while holding breath (i.e. swimming), then the vasoconstriction in the arms and legs forces anaerobic metabolism to occur there = build up of lactic acid, and causes myoglobin in the muscles to release oxygen

For motionless breath holding, the time you can hold your breath for is determined by:
1. Psychological resistance to the urge to breathe
2. Total oxygen storage capacity (= lung volume + blood volume + hemoglobin concentration in blood)
3. Oxygen consumption rate ( = metabolic rate), determined by body temperature, fitness level, vasoconstriction level, and relaxation level; also requires an empty stomach for lowest metabolic rate
4. Resistance to low oxygen levels (better resistance to low oxygen = longer breath hold)

I hope that helps.

 

[trux]

If you want to study the physiology of breath-hold diving more seriously, then besides browsing this forum, you can have a look at some scientific studies. I have assembled collection of some 600 documents related to the physiology of breath-hold diving here:

documents medical @ APNEA.cz

You can often read about the physilogical reactions Eric described under the term "diving response", and also "diving reflex" or "mammalian reflex", "immersion reflex" etc.

 

[upp3rd0g]

Ok, now I am overwhelmed with input. Exactly what I was asking for.

I will now start reading up on the subject.

One last question for you experts (which may sound weird):

Would you be able to think of a medical explanation why my urine starts flowing when I am holding my breath up to 10 - 15 seconds after the gasping reflex starts.

Background: I am suffering from paruresis which means I cannot always pee when I want to. For more information please see this link:

FAQ Page 23

So I learned this magical trick called breath-holding (which helped me out of uncomfortable situations many times) but it seems nobody can explain why it works. That is why I ended up here...

 

[efattah]

Apnea stimulates the vagus nerve. When the vagus nerve is excited, the body's elimination is stimulated.

Apnea also creates vasoconstriction, which causes fluid to pool in the core, which makes the kidney's sense overhydration -- and stimulates urination.

 

[trux]

There may be different reasons for the paruresis - from purely psychological to some physical obstacles like for example an enlarged prostate. So besides what Eric wrote, the breath-hold induced vasoconstriction can also help draining the prostate of blood and reducing so its volume, and facilitating the urination. Or it can be also the mental effect of concentrating on something else than the actual peeing, while generally relaxing. In other words, the effects of breath-hold are multiple.

 

[upp3rd0g]

I am so excited by the information given here! On a paruresis forum there is this returning discussion going on what makes the breathholding work. I would love to understand its principles so I can better teach others how to do it!

Would you guys be able to comment on the following?

A common idea on the working of breathholding is that you induce hypoxia which results in an unknown physiological process starting to "reroute" oxygen to important organs and taking away the oxygen from the inner sphincter (which is controlled by the autonomous nervous system). All this resulting in the flow of urine.

Another thing that came to mind... freedivers don't wet themselves right? So how come the mechanisms explained here don't affect freedivers?

@Trux

You are completely right, paruresis is a social fobia so its psychological. Many people affected by paruresis went to a urologist to confirm there was nothing physical wrong. Distraction techniques are also tools which can sometimes be useful.

Did I already express how happy I am having found this forum with the experts on the topic of breathholding? I hope the fact my questions are off-topic to freediving are not of any concern to anybody.

I will now start reading up on the vagus nerve and all the magic it can do. I also plan to search this forum to find out if you guys have any tricks how to deal with the annoying (but apparently essential) gasping for air feeling.

 

[trux]

Yes, besides the vagus nerve that innervates abdomen organs including the bladder, have a look at the symphatetic nervous system too. Besides others, it is also responsible for urinary output. And during apnea, the symphatetic system is being activated, so it is likely another factor contributing to easier urination.

So, currently I see all these factors that may help with the paruresis:
- mind distraction
- relaxation, muscular decontraction
- vagus nerve stimulation
- symphatetic nervous system activation
- vasoconstriction draining the prostate
- vasoconstriction causing kidneys sensing overhydration (as Eric explained)

EDIT: apnea also causes the release of diverse stress hormons, where possibly some of them may contribute to the stimulation of the urination reflex too

Not sure what percentage of freedivers piss on themselves. Even if diverse factors contribute to easier urinating or the urge to do it, you still do have control of it. It does not happen to me, but I know that some freedivers and spearfishers do urinate when in water, and you will find plenty of threads here on DB discussing it.

 

[Kars]

LOL, urinating in water, well in my experience it's pretty common. Diving in cold water it's nice to have some warmth But in the pool I try to have an empty blather before I get in, in order to avoid discomfort or urinating. When I do it's not visible because I did not eat for many hours and did drink a lot of water, so it's colourless.

I have an idea to induce a faster reaction, try doing an exhale breath-hold.
Also moving produces a lot of CO2, so when you walk to the toilet start your breath-hold in advance
In regard to comfort, you can relax parts of your body while your walking, and mentally sort go into an trance like detached observation mode, noting all the funny changes that happen, while keeping your body and mind relaxed. A little smile will help to relax the numerous face muscles.

I don't know where you live in the Netherlands, but if you want to come over to my area and share a training with me in central Brabant, just Personal Mail me. Tonight I'll be in the pool in Oisterwijk from 20:00 - 22:00. Next Sunday I'll be there from 11:30 - 14:00.

Nice to know another possible medical reason to learn freediving
We already got nice ones such as - overcoming asthma, depression and stress.

Love, Courage and Water,

Kars

 

[trux]

Just a word of caution: when holding your breath, you always risk a blackout. The risk of blackout increases when urinating - it can result in drop of pressure and a vasovagal syncope. More precisely it is called micturition syncope. It happened to me a few weeks ago (without holding my breath, just waking up too abruptly deep in the night and being at the toilet). When I woke up a few minutes later on the ground I had a bleeding nose, a deep cut in a lip, and two teeth broken :blackeye

 

[upp3rd0g]

I have an idea to induce a faster reaction, try doing an exhale breath-hold.
Also moving produces a lot of CO2, so when you walk to the toilet start your breath-hold in advance

Good tips, that is exactly what I do!

Let me explain a little further what I do and how I do it and why I do it.

It starts with the realization I need to pee and a difficult toiliet situation is about to come. When I have decided I will use breathholding I do this:

1) be relaxed, breath in and out normally, do not physically strain myself
2) exhale 75% approximately
3) start holding breath
4) wait for contractions to start
5) sit through the annoying feeling of gasping for air for 10 - 15 more seconds
6) slowly start peeing
7) at this point you really want to inhale, if you do that possibly the urine stream may stop, if so, repeat stap 1 - 7
8) use Vasvalva manoeuvre to put extra pressure on the bladder so I can maintain my urine flow

Step 1 - 3 can already start outside the toilet.

So with step 1 - 6 I can always induce my urine-flow. There is no specific need for a threadfull situation, or an urge to pee, or whatever. It just works in all cases.

A problem arises in step 7 where the inhalation and/or exhalation of breath many times affects the urineflow. It seems I interrupt specific physiological processes, but I don't understand exactly what I interrupt.

There are many people who confirmed they managed (after some practice) to learn the trick of breathholding. It is to them, just like it is to me, a lifesaver.

There are also several persons who cannot get it to work, which makes some people say: breathholding is a trick which does not work for everybody. You are either lucky or unlucky if you get it to work or not. What do the experts here think of this statement?

Does anybody have any specific tips how I may improve step 1 - 7 in a way it:

a) is less annoying
b) the effects kicks in quicker

Does anybody have any tips how to teach this to somebody who claims he cannot do it?