The Oxygen Advantage

Simple, Scientifically Proven Breathing Techniques to Help You Become Healthier, Slimmer, Faster, and Fitter

By: Patrick McKeown

Published: 2015

Read: 2017


We breathe in oxygen and we breathe out carbon dioxide (CO2).

The reason we feel the need to breathe is mostly because of the rising level of CO2 inside our body and to a lesser degree, the decline in oxygen. CO2 not only plays a central role in the intake of oxygen, it also regulates the uptake of oxygen from red blood cells by our muscles and organs (the Bohr effect).

While CO2 regulates when we breathe and how efficient we are in using our oxygen, the manner in which we breathe in turn determines the level of CO2 present in our blood: for instance, mouth breathing or an excessively high volume or rate of breathing releases too much CO2. This has many adverse effects, including reducing our ability to use oxygen efficiently. 

This book  highlights the importance of proper breathing to ensure that the level of CO2 is sufficient to handle the body’s requirements for oxygen. Maintaining proper breathing patterns is especially challenging when we face increased levels of CO2 and/or lower levels of oxygen (for instance, when we exercise, we have an urge to breathe heavily). Improving our ability to tolerate these higher levels of CO2 and lower levels of oxygen will allow us to better regulate our breathing, avoiding an excess loss of CO2 and allowing CO2 to do its job in helping to meet the body’s need for oxygen.

The book provides a number of useful techniques to pursue these abilities. These techniques include regular, nose and abdominal breathing (to avoid (getting used to) excessive losses of CO2), simulating high altitude training (to improve tolerance to lower levels of oxygen) and various breath-holding techniques (to improve tolerance to higher CO2 and lower levels of oxygen).

Ultimately, this should result in a virtuous cycle of better breathing patterns, increased performance / endurance, increased lactic acid tolerance, and increased oxygen carrying capacity.

Worth Reading:

A good, at times repetitive, reminder on the importance of paying attention to how we breathe. To this point, the book includes helpful and practical breathing exercises.

Perhaps the title should have been “The CO2 Advantage” instead, as it mostly focuses on the central role played by CO2 in the regulation of oxygen intake and uptake.

The book is also helpful in explaining the importance of nose breathing (nitric oxide).

Through a rudimentary explanation of the mechanics of our respiratory system, the book provides helpful tools to understand other breathing and breath-hold techniques (Wim Hof, bhramari breathing, etc.) and to assess whether or not they may be interesting to pursue.

Practical Takeaways:

  • CO2 drives the intake of oxygen:
    • You breathe primarily to eliminate excess CO2 from the body.
  • CO2 drives the uptake of oxygen:
    • The Bohr effect: oxygen is released in the presence of CO2.
  • Exercise lowers oxygen (hypoxia) and increases CO2 (hypercapnia)
    • To maintain performance, train your reaction to hypoxia and hypercapnia.
  • Dealing with higher CO2 (CO2 tolerance):
    • Avoid getting used to low levels of CO2.
      • Yes: regular, nose abdominal breathing. 
      • No: heavy, mouth upper-chest breathing.
    • Get used to high levels of CO2.
      • Breath-hold exercises.
  • Dealing with lower oxygen:
    • Breath holding exercises and simulated altitude training:
      • Increases production of natural EPO, stimulating the maturation of red blood cells in bone marrow.
      • Increases release of red blood cells from the spleen, improving your oxygen carrying capacity.
  • Benefits of nitric oxide:
    • Nose breathing helps to move nitric oxide from the nasal airways to the lower airways and the lungs.
    • Nitric oxide relaxes blood vessels, improving blood flow and lowering blood pressure.

Key Concepts:

CO2 drives the intake of oxygen:

  • Your breathing rate and volume are determined by receptors in the brain that monitor the concentration of CO2, oxygen and the acidity of your blood. 
  • CO2 is an end product of the natural process of breaking down the fats and carbohydrates that we eat.
  • CO2 is returned from the tissues and cells to the lungs via the blood vessels, where any excess of CO2 is exhaled.
  • When levels of CO2 increase above a certain amount, these receptors stimulate breathing in order to get rid of excess CO2.
  • Correct breathing relies on and results in the “right” amount of CO2 being retained in your lungs. 

CO2 drives the uptake of oxygen (and some other things…):

  •  Regulating the delivery of oxygen from the blood to the muscles and organs.
    • Haemoglobin, a red protein responsible for transporting oxygen in the blood, releases oxygen when in the presence of CO2 (known as the Bohr Effect).
      • As seen in exercising muscles, which generate CO2, in turn triggering the release of oxygen from its capillaries.
    • When we over-breathe, too much CO2 is released from the lungs, blood, tissues and cells, causing the haemoglobin to hold on to the oxygen, resulting in reduced oxygen delivery to tissues and organs (hypocapnia).
  • Regulating the dilation of the smooth muscle in the walls of the airways and blood vessels.
    • Blood flow reduces proportionally to a reduction in CO2.
      • For instance, heavy breathing for an extended period of time substantially lowers CO2, which can bring about dizziness due to reduced blood flow to the brain.
  • Regulating blood pH
    • How acidic or alkaline your blood is.
    • Normal pH in the blood is around 7.4.
      • If pH is too acidic, below 6.8, or too alkaline, above  7.8, the result can be fatal.
    • If blood pH is too acidic (for instance, due to the over-consumption of processed foods), this can bring about heavy breathing, lowering CO2, allowing pH to normalize.
    • If blood pH is too alkaline, breathing reduces or regularizes to allow the level of CO2 to build up. 

Exercise lowers oxygen (hypoxia) and increases CO2 (hypercapnia):

  • During strenuous exercise, the consumption of oxygen increases, slightly lowering the concentration of oxygen in the blood.
  • At the same time, increased muscle activity and metabolic rate produce more CO2, causing an increased concentration of CO2 in the blood.

To maintain performance, you need to train your reaction to hypoxia and hypercapnia:

  • The sensitivity of your CO2 receptors (ie, your CO2 tolerance) determines how you deal with hypercapnia.
    • When you have a strong response to CO2, breathing will become intense and heavy, causing CO2 levels to drop, lowering the amount of oxygen delivered to working muscles, resulting in overexertion, breathlessness, etc.
    • Conversely, having a greater CO2 tolerance allows for continued regular breathing, more effective delivery of oxygen to the working muscles, reducing the risk of inflammation, tissue damage and injury.
  • In order to maintain performance, it is essential that your breathing does not react too strongly to increased levels of CO2 (and decreased levels of oxygen).
    • Training helps to condition the body to tolerate changing levels of CO2 and oxygen. 
    • Having an ability to tolerate higher concentrations of CO2 in the blood is correlated with higher levels of endurance.

Increase ability to deal with high CO2: avoid getting used to low levels of CO2:

  • Prolonged unnecessary losses or low levels of CO2 lower your ability to deal with and respond to higher levels of CO2.
  • Avoid big breaths or heavy breathing: take regular moderate breathes.
    • Not necessary to increase the oxygenation of the blood: your blood typically is already saturated.

    • Oxygen saturation, the percentage of oxygen-carrying red blood cells containing oxygen within the blood, typically ranges between 95-99%. 
      • If it is closer to 100%, it perhaps means that oxygen is not sufficiently being deposited out of the blood to where it is needed.
  • Avoid mouth breathing: breathe through your nose.
    • Most of the animal kingdom relies on nasal breathing, allowing them to eat and breathe at the same time. 
    • For humans, the primary benefit of nose breathing is that it helps to move nitric oxide from the nasal airways to the lower airways and the lungs.
      • Nitric oxide flows with the inhaled air into the lungs where it makes the blood vessels in the alveoli expand.
      • This allows a greater volume of blood to flow, resulting in an increase of the amount of oxygen that can be taken up.
      • In the absence of sufficient levels of NO, blood vessels don’t relax and dilate, blood circulation slows and the heart has to pump harder (ie, increase blood pressure) 
      • The production of nitric oxide can be improved by simple humming.
        • As used in certain meditation techniques such a Brahmari breathing.
    • Other benefits of nose breathing include:
      • Warms and humidifies the incoming air flow.
      • Removes germs and bacteria.
    • Mouth breathing is synonymous with emergency, activating the fight-or-flight response.
      • Mouth breathing activates the upper chest, involves larger breaths and may cause reduced oxygen uptake. 
  • Avoid upper chest breathing: breathe deeply into your abdomen using your diaphragm.
    • The respiratory system comprises the parts of the body that deliver oxygen from the atmosphere to your cells and transport the CO2 produced in your tissues back into the atmosphere.

    • When we breathe, air enters the body and flows down the windpipe into the lungs, into small airs sacs called alveoli.

    • The alveoli are surrounded by blood vessels (capillaries), allowing them to transport oxygen into the blood. From the blood stream, oxygen is delivered to muscles, organs and tissues. 

    • A deep breathe means breathing down into the full depth of the lungs, using the main breathing muscle, the diapragm (the muscle separating the chest from the abdomen). 
    • Abdominal breathing, bringing air into the depths of your lungs, is more efficient, because the lungs are wider at the bottom, containing more alveolis, allowing for greater blood flow and oxygen absorption. 

Increase ability to deal with high CO2: breath-hold exercises.

  • Practice breath holding techniques.
    • Increased exposure to high levels of CO2. 
    • Know your BOLT score (see below).

Increase your ability to deal with low oxygen: high altitude and breath-holds.

  • Create air shortage (hypoxia) by breathing less than you feel the need to during physical training.
  • Increases red blood cell count.
    • Blood is made up of oxygen carrying red blood cells, white blood cells and plasma.
    • The reduced availability of oxygen stimulates the kidneys to increase production of EPO.
      • EPO is a naturally occurring hormone that stimulates the bone marrow to release more red blood cells into circulation.
    • Hypoxia also induces the spleen to contract and release more red blood cells into the blood circulation.
      • The spleen is an organ that acts as a blood bank: when the body signals an increased demand for oxygen, the spleen releases stores of red blood cells.
    • The increased amount of red blood cells leads to a higher oxygen carrying capacity of the blood, improving aerobic capacity.

Breath-hold exercises:

Nose unblocking exercise:

  • Small nose breath, in and out.
  • Pinch nose.
  • Hold breath and walk as long as possible. 
  • Resume breathing through nose.
  • Repeat after two minutes.
  • Repeat six times.

Improving your BOLT score:

  • The body oxygen level test (BOLT), the length of time you can comfortably hold your breath (without “pushing it”), measures the match between your body’s breathing volume and metabolic activity.
  • When your breathing volume matches the amount of CO2 produced, it is easier to exercise at a higher intensity level. A score of 30 seconds or higher indicates a reasonable match.

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