Wednesday, November 2, 2016

Stuff I Learned - Week #9

Your respiratory system relies on feedback from your body
to determine the depth and rate of breathing. This diagram is an example of a
mechanical system that also uses feedback.
In last week's post, I briefly discussed how yogic deep breathing isn't necessarily how you should breathe throughout your day. Did you get a chance to view Leslie Kaminoff's video? I got quite a kick out of his story... largely because I have similar stories! But rather than boring you with tales of runs-gone-awry, this week I'll go into a little more depth on the mechanisms underlying cardiorespiratory control.

An example of a feedback loop
In the earliest days of automotive fuel-injection, the fuel was simply squirted into the combustion chamber. (do you remember before there was fuel-injection; when cars had carburetors?) While there was some rhyme and reason to the amount and timing of the squirt, too much or too little fuel was often injected into the engine. When too little fuel was injected, the engine could be damaged from overheating. When too much fuel was injected, the fuel economy would suffer.

The just right balance of fuel/air mixture (the stoichiometric ratio) is imperative for optimal function, and was often elusive. In the earliest days of fuel injection (like the bad-old-days of carburetion), the amount of fuel that was squirted into the engine was calculated on a best-guess based on outdated information. The actual real-time conditions were not taken into account in calculating future actions, and as a result, most cars didn't get very good fuel economy... nor did they last nearly as long as cars do, now.

It wasn't until the latter part of the 1970's that a major advance in fuel-injection technology became widely available - the Bosch Lambda system. The Lambda system had a sensor in the exhaust pipe that measured the content of the exhaust gases. If there was unburnt oxygen present in the exhaust gases, then the injectors would adjust to squirt more fuel into the combustion chamber in the next cycle. And if there was too little oxygen present in the exhaust gases, then less fuel would be squirted during the next cycle. The Oxygen Sensor was a major advance in fuel-injection technology because it introduced feedback into the equation. With the advent of Lambda feedback, the car could adjust its fuel utilization based on a real-time data stream, rather than relying on information based on guesswork.

The Body
Now, you may be wondering, what does fuel-injection have to do with yogic breathing? As is often the case in my circular approach to explaining things, everything and nothing! What Lambda-sond (what Volvo called their version of the Bosch system) has to do with the human body is feedback. Feedback is an essential component of maintaining dynamic balance in any system.

Your body uses feedback to determine the depth and rate of your breathing. Moment by moment your body is checking and double-checking that the correct amount of oxygen, carbon dioxide and other gases are present in your bloodstream. And like the prior example with automotive fuel-injection, your body uses this information (feedback) to make informed decisions on its next-steps. Feedback is essential in maintaining balance in the body.

In the human body, there are just-right amounts of the various gases that are present in the bloodstream. We do not simply want more, more, more of any given gas in the bloodstream. For example, the oxygen content of blood must remain within a very small window. Too much oxygen in the blood is every bit as problematic as too little oxygen in the blood. (hence the terms antioxidants, oxidative stress, etc). Your body automatically regulates your breathing depth and rate to maintain the optimal chemical balance with these three primary sensors, or sources of information: Central Chemoreceptors, Peripheral Chemoreceptors and Neural Input.

It goes beyond the scope of this blog to fully unpack the nature of these sensors, though since I've mentioned them, I'd better at least describe their roles in brief:

  • Central Chemoreceptors live in the medulla (brain stem), and they sense the carbon dioxide (and other substances) present in the cerebral spinal fluid. An increase in CO2 content signals the body to increase ventilatory depth and/or rate.
  • Peripheral Chemoreceptors are located in the aorta and carotid arteries, and also sense CO2 (and other substances) content . Similarly to the Central Chemoreceptors, an uptick in CO2 concentrations signals the body to increase ventilatory depth and/or rate.
  • The Neural Input senses signals coming from higher brain centers, along with sensory information coming from the muscles and joints. This information is also used by the respiratory control super-computer to determine depth and rate of breathing.

These sensors automatically send appropriate information to the respiratory control centers of the brain stem. The supercomputer of the brainstem then processes the incoming data so that you will breath in the optimal way. If you try to override the wisdom of this system you may feel buzzed for awhile. But it's virtually inevitable that the skewing of your blood's chemistry by inappropriate deep breathing will lead to feeling worse than if you simply left well enough alone (DFWI).

In summary, your body is very wise. You're generally best off to DFWI when it comes to functions like breathing. While Yogic deep breathing is a time-tested practice, trying to practice deep breathing in daily life is not likely to cultivate optimal health. Since none of us are consciously aware of the concentrations of all the gases within the bloodstream, how can we possibly do a better job of consciously controlling the breathing than the subconscious already does?

Yoga practice is a time to witness the presence of something quite magical, and perhaps to consider the miracle that is this breath... this one, right here. Please, take time whenever possible to notice that you are breathing, which is very different than controlling or regulating your breathing.

side note - please don't believe the claims that oil companies are suppressing fuel-efficiency technologies. The fact that our cars are regularly getting 30+ mpg from a gallon of gas is a triumph of engineering!


Julbear S said...

So, let me open a door... or a window (to let some gasses out ;-) Is there a time and place for Ujjayii breathing? If so, when might a person benefit from such pranayama? Just thinking about it brings to mind images of voter suppression. Hmmm. But to use your car analogy, it seems like Ujjayii is akin to a turbo-boost which might be really useful in certain situations.


Julbear S said...

BTW, I can't think of a time I've taught Ujjayii breathing in my yoga classes. I agree with the notion that for most of us, we're already too up-regulated as if turbo-boosted while driving through downtown traffic. If anything, my default is the long complete exhale with a possible pit stop at the end of the exhale.

To correct my own analogy, maybe it would be more accurate to say that I suggest pulling off the side of the road to take in the view of the vast ocean while driving along the coastline.

People and their sportscars - some like it fast. I hear it's a good idea once in awhile to get on the road and let the throttle open. But is it sustainable?

Oh these analogies...

Scott Anderson said...

By the early 00's, one of my root teachers, Dona Holleman, was teaching that Ujjayi breathing may not have a place in MPY (Modern Postural Yoga). It's a very stimulatory technique, and even people that are very tired are often already adrenalized and needing to relax.
I've not gone to quite that extreme with regards to Ujjayi, though I only teach the technique in moderation (<5-minutes at a time), and only when followed by Savasana.
Benefits? At minimum, the deep breathing helps to open up the ribcage, and may also help to increase ventilatory capacity. There is also benefit to strategically up regulating the sympathetic nervous system as a means to affect a long-term down regulation. (a homeopathic approach)
On a more subtle-body level, the mind also seems to have a unique capacity to recognize itself when an upregulated system is quickly down regulated.

Julbear S said...

Many thanks. Downshifting now to 2nd gear!