Breath Control and Blood Pressure

[berkeman]

When I free dive (skin dive without a scuba air tank), I've noticed that by the time I get out of the water after about an hour (abalone diving or just recreational free diving), I feel like Jello and my blood pressure (BP) feels very low. I feel extremely relaxed and warm and happy. And after a target shooting session at the range, I feel the same way.

Both activities involve breath control. In free diving, I hyperventilate a bit (not too much), and then I hold my breath for about a minute under water. Then I recover for about a minute on the surface to re-oxygenate, and do it again. At the shooting range, I take a deep breath, let about half of it out, and then stay at that diaphragm setting for the next few seconds as I squeeze the shot off. You are trying to minimize all muscle movements during that time.

After both activities I feel a very noticeable relaxed state, and I'm pretty sure my BP is down quite a bit. I'd like to figure out how to translate this into my everyday life, since there are times at my EE work where it is very stressful and I can feel my adrenile level climb and I'm sure my BP is spiking.

Does anyone have references to breath control and BP? The effect seems so significant from my personal experiences. I've done a bit of searching online, but I think I probably am not using the right search terms. Thanks folks.

https://freediveinternational.com/wp-content/uploads/2015/06/freediving-dahab.jpg

 

[Bystander]

https://en.wikipedia.org/wiki/Yoga_as_exercise

 

[BillTre]

I am have no doubt that a lot of this can involve long hours of training at breathing control or focusing your inner stuff.
However, I am more interested in the biology I think would be underlying things like this.
The diving part of your story reminded me of the diving response, when you hold your breath and wet your face, your body's oxygen supply system changes as if it were going to deal with prolonged submersion. It is for my purposes, a model physiological response. It produces some kind of low energy use metabolic state, take it easy kind of state, where you are relaxed and calm (as you should be if you are going to conserve energy).

The most noticeable effects are on the cardiovascular system, which displays peripheral vasoconstriction, slowed heart rate, redirection of blood to the vital organs to conserve oxygen, release of red blood cells stored in the spleen, and, in humans, heart rhythm irregularities.[2] Although aquatic animals have evolved profound physiological adaptations to conserve oxygen during submersion, the apnea and its duration, bradycardia, vasoconstriction, and redistribution of cardiac output occur also in terrestrial animals as a neural response, but the effects are more profound in natural divers.

This is something conserved among mammals. It is probably the result of a autonomic nervous system state.

The triggers for the diving response are:

chilling and wetting the nostrils and face while breath-holding

In more detail:

When the face is submerged and water fills the nostrils, sensory receptors sensitive to wetness within the nasal cavity and other areas of the face supplied by the fifth (V) cranial nerve (the trigeminal nerve) relay the information to the brain.[1] The tenth (X) cranial nerve, (the vagus nerve) – part of the autonomic nervous system – then produces bradycardia and other neural pathways elicit peripheral vasoconstriction, restricting blood from limbs and all organs to preserve blood and oxygen for the heart and the brain (and lungs), concentrating flow in a heart–brain circuit and allowing the animal to conserve oxygen.

Specific sensory triggers water on face and in nostrils.
Signals go from nerves innervating the face (Trigeminal (V) nerve), to the hindbrain (central processing site for metabolic controls), then out the Vagus (X) nerve to the autonomic nervous system (involving lots of peripheral ganglia).
I would hypothesize that effects of the autonomic nervous system were responsible for a lot of your experience.

I would think of the diving response as a model of in what manner can a different functional autonomic state be invoked.
Breath holding is also involved as a trigger of the diving response, which ties in with the shooting situation:

In humans, the diving reflex is not induced when limbs are introduced to cold water. Mild bradycardia is caused by subjects holding their breath without submerging the face in water.[8][9] When breathing with the face submerged, the diving response increases proportionally to decreasing water temperature.[7] However, the greatest bradycardia effect is induced when the subject is holding breath with the face wetted.[8] Apnea with nostril and facial cooling are triggers of this reflex.

I would expect that new triggers could be learned and the strength of old ones to be malleable, allowing one to find different ways of reaching equivalent final autonomic states.

In a tense situation, maybe holding your breath and splashing some cold water on your face/nostrils will invoke some of the diving response for you.

 

[Rive]

Does anyone have references to breath control and BP? The effect seems so significant from my personal experiences. I've done a bit of searching online, but I think I probably am not using the right search terms

I think it'll be 'breath holding CO2 vasodilator' or something like that.

Ps.: I have no relevant knowledge: I have just picked up the google challenge again...

 

[atyy]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505554/
Breathing control center neurons that promote arousal in mice.
Yackle K, Schwarz LA, Kam K, Sorokin JM, Huguenard JR, Feldman JL, Luo L, Krasnow MA.
Science. 2017 Mar 31;355(6332):1411-1415. doi: 10.1126/science.aai7984. Epub 2017 Mar 30.

"Although breathing is commonly viewed as a simple autonomous function that sustains life, it has long been known to influence higher order behavior and thinking (1). Slow controlled breathing is used by practitioners of pranayama yoga and other forms of meditation to promote mental calming and contemplative states, and it is used clinically to suppress excessive arousal and stress such as certain types of panic attacks (2,3). While the effect of breathing on behavior and mental state could easily be indirect, there could also be more direct connections and impact of the breathing center on higher order brain function (4), as demonstrated here. ...

We propose ... This respiratory corollary signal would thus serve to coordinate the animal’s state of arousal with the breathing pattern, leaving the animal calm and relaxed when breathing is slow and regular, but promoting (or maintaining) arousal when breathing is rapid or disturbed."

 

[Fervent Freyja]

Couldn't find anything that the Navy has offically published, but Box Breathing is a technique endorsed by the Navy SEALS.

 

[Fra]

Any technique that increases your parasymphatetic tone and reduces your symphatetic tone (which is why it means to relax in terms of ANS) would typically reduce HR and reduce blood pressure by various other mechanisms likes vasodliation.

As for the physiology in yoga techniques i think this is complex. Some have suggested that deep breathing (high amplitude breathing) may stimulate the baroreceptors to increase the vagus tone, as for nose breathing as opposed to mouth breatthing i recall having seem some theories that the vibration in nostrils stimulate the vagus nerve. And due to a biological left/right assymmetry of the innervation of the vagus nerve on the heart, left vs right nostril blocking technique has different effects. right vagus nerve mainly innervates the SA node, and thus reduces heart rate. But left vagus innervates the AV node more, and thus left vagus electrical stimulation is a possible alternative to medication against some arrythmias caused by increased autonomy of other pacemakercells. Here right vagus stimualtion would simlpy cause bradychardia rather than merely reducing arrythmia.

Other than this simply focusing on harmonic and calm breathing may be a cognitive "trick" to make your brain getting a pause from stressful thoughts. Ie. instead of just "stop thinking about stressful things", an easier way is to try to focus on something trivial, such as breathing. Just like the magicians tricks to make you not see, is to make you look at something else :)

There is no question this has some good physiological grounds but it seems a complex system, with more than one mechanism involved. Its both cognitive mechanism and physiological/biological mechanisms working together.

/Fredrik

 

[Fra]

Other than this simply focusing on harmonic and calm breathing may be a cognitive "trick" to make your brain getting a pause from stressful thoughts. Ie. instead of just "stop thinking about stressful things", an easier way is to try to focus on something trivial, such as breathing. Just like the magicians tricks to make you not see, is to make you look at something else :)

As for focusing on trivial things. Another thing i consistently find relaxing is soldering :) IF you have 20 projects going on in your head normally, and if you end up in a situation where you like have to solder some conenctors. Just focusing on ONE wire at a time, is as good as yoga to me ;) Its like a perfect excuse to clear it from the 20 projects and just do one wire at a time.

/Fredrik

 

[Tom.G]

Just focusing on ONE wire at a time, is as good as yoga to me ;) Its like a perfect excuse to clear it from the 20 projects and just do one wire at a time.

Also known as "Taking a Break."
Edit: or "Decompressing."

 

[James Briggs]

You might want to talk to the RESPeRATE people. The have a machine that measures your breathing rate because when you lower it your blood pressure drops.

 

[berkeman]

You might want to talk to the RESPeRATE people. The have a machine that measures your breathing rate because when you lower it your blood pressure drops.

Interesting, thanks for the link. I'm pretty good at counting respirations (especially my own), so I'll skip paying the $200-$300. It could be useful for some folks, I would think.

 

[skeptic2]

I have a blood pressure monitor at home and have discovered that hyperventilating lowers both my blood pressure and my pulse. It seems that if the blood is more oxygenated, the heart has to work less hard to oxygenate the organs. And conversely, holding my breath raises both my blood pressure and heart rate.

 

[Tom.G]

Interesting.
Just checked pulse and O₂ saturation.
sitting quietly: 68, 97%
hyperventilate: 84, 99% (pulse up 24%)
holding breath: 94, 94% (pulse up 38%)

 

[J Boogie]

My friend who just got into free diving said the current wisdom is against hyperventilating prior to diving because this increases heart rate and BP as per above data. Best physiological state for prolonged underwater state is relaxed as possible.

 

[skeptic2]

I just finished checking my bp and pulse and here are the results.
BP Pulse
sitting quietly 133/72 87
hyperventilating 121/62 93
holding breath 127/83 85

Obviously results vary.

 

[berkeman]

When I free dive (skin dive without a scuba air tank), I've noticed that by the time I get out of the water after about an hour (abalone diving or just recreational free diving), I feel like Jello and my blood pressure (BP) feels very low. I feel extremely relaxed and warm and happy. And after a target shooting session at the range, I feel the same way.

Both activities involve breath control. In free diving, I hyperventilate a bit (not too much), and then I hold my breath for about a minute under water. Then I recover for about a minute on the surface to re-oxygenate, and do it again.

My friend who just got into free diving said the current wisdom is against hyperventilating prior to diving because this increases heart rate and BP as per above data. Best physiological state for prolonged underwater state is relaxed as possible.

I guess I should have been more precise. My breathing when free diving is not so much hyperventilation before doing the surface dive. When I get back to the surface, there are of course a couple very deep and long breaths, followed by relaxed deep slow breathing. Then the last couple of breaths are deeper than normal, but still slow and methodical. That seems to do the best job of re-oxygenating me, while maintaing as relaxed a state as I can. I apologize if my use of the word "hyperventilate" implied a hurried, non-relaxed breathing pattern.

I'd be very interested in seeing what your friend is learning about free diving breathing patterns that are recommended now. It's been decades since I learned (right when the movie "Jaws" was released -- good timing berkeman!)

 

[Fra]

Interesting.
Just checked pulse and O₂ saturation.
sitting quietly: 68, 97%
hyperventilate: 84, 99% (pulse up 24%)
holding breath: 94, 94% (pulse up 38%)

Just a note on your measurements that look supicious. Your SpO2 values doesn't make sense (unless you have a problem with your lungs, for example patients with largely reduced lung capacity due to cancer etc, get really low SpO2 values and need to get supplements from pure oxygen, to keep the levels from reaching critical levels).

Normal range is >95%, i suspect maybe something went wrong during your measurement. If the finger blood perfusion is poor (if that is where you put the sensor), it can also be difficult to get an accurate reading at all. So maybe variations in peripheral circulation can explain your strange data.

/Fredrik

 

[Tom.G]

Normal range is >95%, i suspect maybe something went wrong during your measurement.

Perhaps my post was unclear. The parenthetical statements were to indicate the percentage change in pulse rate, not the SpO₂ values. The lowest SpO₂ value was 94%, when hypoventilating. Maybe could have driven it a little lower but it was getting uncomfortable.

Or am I misunderstanding your comment?

 

[Fra]

Perhaps my post was unclear. The parenthetical statements were to indicate the percentage change in pulse rate, not the SpO₂ values. The lowest SpO₂ value was 94%, when hypoventilating. Maybe could have driven it a little lower but it was getting uncomfortable.

Or am I misunderstanding your comment?

Ah now i see. Yes i totally misread your post. Sorry.

When you wrote 68, 97% i read it as SpO2 = 68.97% (which would have been odd anyway to note two decimals), but now i see i mixed up decimal symbol with column separation :)

/Fredrik