The Science


Section 1: The Science

Chapter 1: How we have come to fall under the Spell of The Oxygen Illusion

Our atmosphere has an abundance of oxygen. The air contains 21% O2, but we breathe only 5% of it. The rest we breathe out. In addition, the cells only make use of only 1/4 of the oxygen we breathe. Oxygen is obviously never a problem. We always have more than enough. Learn more about what really is the problem.

Chapter 2: Oxygen Uptake in Rest and Exercise – You might be surprised

The subject of oxygen metabolism during exercise is maybe the most studied aspect of exercise physiology. But still, so much is misunderstood and misinterpreted because of The Oxygen Illusion. Here you will learn the truth. And how to use this truth to increase the speed of your recovery.

Chapter 3: The Lactic Acid Illusion – Are your ready to recover from it?

Lactic Threshold corresponds to exhaustion in exercise so Lactic Acid has a negative association in exercise physiology. But this is an illusion. Even though The Lactic Acid Illusion was cleared up decades ago, it still persists. Lactic Acid is not the nemesis of your exercise tolerance. It is actually protective. It makes you able to exercise more because it helps to lower the metabolic acid. But did you know CO2 has the same role? It protects against the metabolic acidosis induced by exercise. This might be difficult to understand, so please read on to learn the truth about it here.

Chapter 4: The Secret to Increasing Blood Flow – The Foundation of Recovery

There is one element in our physiology that connects all other elements of our physiology. Blood Circulation. And there is one way to increase blood circulation and simultaneously decreasing the metabolic demand. Learn how RecoveryBreathing increases blood flow and speed of recovery.

Chapter 5: Your Most Abundant Antioxidant – Its Not What You Think

It free. Its everywhere. Always available. It protects and strenghtens all other antioxidants. And you have complete control of it by using breathing. This might surprise you. It is CO2. Learn more about how CO2 acts as an antioxidant here.

Chapter 6: Inflammation and How it can be Avoided

Inflammation is one of the culprits of exercise-induced muscle damage and DOMS. But inflammation is not just inflammation. There are many types. Learn which types of inflammation you get from exercise and how these are relieved and avoided by using RecoveryBreathing.

Chapter 7: Pain Reduction With Recovery Breathing

There are many theories about how and why we get muscle soreness after exercise. But there is no doubt about one thing when it comes to muscle soreness: it hurts and it hurts the most during day 2 and 3. Here you will learn how reducing your breathing rate to such levels as achieved by RecoveryBreathing actually makes you able to immediately reduce the pain drastically.

Note: The graph are based on the real science but do ot show the exact numbers. They are made to portray the relative relationships between factors associated with RecoveryBreathing.

RecoveryBreathing elements

The real voyage of discovery consists not in seeking new lands but seeing with new eyes. – Marcel Proust

Chapter 1: How we have come to fall under the Spell of The Oxygen Illusion

We must take a closer look at the physiology of breathing before we can begin to grasp what we can use the breath for.

The first step toward knowledge is unlearning what you thought you knew.

Let us first of all note that the breathing function from breath to breath is not about oxygen. Yes, you read that right. Breath is not primarily about oxygen. It is first and foremost about carbon dioxide (CO2). Oxygen is important, without it we will surely die, but it is not as important as we have thought.

We have grown into the misconception that oxygen is the most important thing we have. A life-giving, life-enhancing, unconditionally positive molecule. We have been led to believe that the more we have of it the better. It is not that simple. We have actually been led astray. But this only becomes obvious when someone points it out.

If oxygen where the reason for breathing we would breathe once every two or three minutes!

Our atmosphere has an abundance of oxygen. The air contains 21 % O2, but we breathe only 5 % of it. The rest (16 %) we breathe out. In addition, the cells only make use of 1/4 of the oxygen we breathe. That means we only use 1,25 % of the oxygen we have available in the air we breath. The rest is stored safely within the red bloodcells. We have more than enough of it at any time.

Even when we go to high altitudes with half the oxygen available in the atmosphere, all it takes is a few weeks of adaption and the cells has more than enough oxygen available again. The adaption that happens is an increase in capillary blood flow. So even when there is less oxygen in the air, there is more oxygen availbale to the cells.  (Beall 2007)

Oxygen is obviously not as important as we might think. It is the delivery of oxygen that is important.

Oxygen supplementation is still in use both in medicine, in sport and in recovery. In some situations it saves lives. But it is also used in situations where it actually harmful. And the detrimental effects of oxygen has been difficult to see because of The Spell of The Oxygen Illusion; the mindset that believes more oxygen is better for all people.

We need to look closely at what really happens in a hyperoxic situation (high oxygen levels in the blood).

What we will see is that the bloodvessels contract and there is actually less nutrients delivered to the cells. And we will see that the oxygen push out the CO2 which makes the oxygen actually get stuck on the bloodcells and wont be of much use to the mitochondria. The tissues experience hypoxia (low oxygen levels) even though the blood is hyperoxic. More on that later. (Iscoe 2011)

It has also been suggested by several scientists that we need to change our view on oxygen and the function of the circulatory system. Because life appeard in an environment which was hypoxic and hypercapnic (high CO2 levels), and because the environment in the mitochondria within our cells is pretty much the same as it was 2 billion years ago when life appeared, it is actually better for our organism to keep oxygen levels low. Recovery Breathng makes full use of these principles. (Massabuau 2003, Hsia 2014)

Oxygen saturation in the blood is 96-98 % regardless if your breathing is fast or slow, deep or shallow. However, the amount of CO2 in the blood significantly changes if you modify your breathing pattern just a tiny bit. Within just a few minutes of hyperventilation, the CO2 level will be so low that you probably will faint (O2 level is still 98 %). On the other hand, if you breathe with just a little slower breathing rate,  the level of CO2 can increase significantly (while the O2 level goes down to 96 %, still within normal range). Oxygen saturation can be measured with a simple pulse oximeter. It is easy and fun to do the experiments at home.

Breath-by-breath co2 concentration Breath-by-breath O2 saturation

Similarly, when you hold your breath, it is the increase in CO2 that prompts the first need to breathe again. For most people, this need comes after 30-40 seconds, for others just five seconds. Even though we sense the feeling of breathlessness, there is  still more than enough oxygen available. It takes about one minute before the oxygen level begins to decrease slowly. The physiological need for oxygen does not appear until oxygen saturation is way down at 65 %, and this takes several minutes. (Laurino 2012)

Oxygen saturation in breath-hold

We can now begin to realize that oxygen is a destructive molecule. The more oxygen you consume in your body, the faster the cells are broken down. This is called oxidative stress. Oxygen is the reason why metal rusts or apples rot. It is also concideren one of main reasons we age. Therefore, we need antioxidants.

We usually think of oxygen as the source of vitality and life energy, but it is in fact a destructive molecule that has a positive effect only in very limited quantities. It is the antioxidants which is the true source of vitality as they protect us from the damaging effects of oxidative stress, and CO2 is perhaps the most important and most readily available antioxidant since we can control it with your breath.


But let ‘s look closely at what CO2 actually does in the body.

CO2 is not a waste product as many have been led to believe. It is in fact one of our most important parahormones to perform many tasks on its way from the mitochondria, where it is produced, through the bloodstream to the lungs. Since we can raise and lower the CO2 with simple breathing techniques we can get a whole new understanding, both practical and theoretical, of how breathing works in restitution when we realize that CO2 is not a waste product.

batman Co2 enough

Personally, I have not experienced DOMS since I discovered this principle. And I’ve done everything I can to experience it. Everything from heavy squats, trekking at high altitude in the mountains, sprint intervals up hills, martial arts intensives, etc. With proper use of breath the soreness evaporates during day 2, where it usually reaches its peak.

It is interesting to note that the oxygen uptake is dependent on the fact that we have enough CO2 in the blood. During hyperventilation, eg. a panic attack, the CO2 concentration in the blood decreases. Once the blood has low CO2, the O2 molecules are stuck on the blood cells. Although we have an abundance of oxygen in the blood, nothing reaches the muscle tissue or brain cells. The oxygen only keeps revolving around and around in the body like a carousel without any benefit and the result is dyspnea.

It is only when we faint,  and the breathing slows down again, or if we breathe in a bag so that we can breathe the CO2 back into the blood, that we can regain our breath because the oxygen jumps off the blood cells and can be used by the brain and muscles again.

In conclusion, the CO2 is necessary to get the benefit of the oxygen we breathe. Without CO2 in the blood, the O2 can not reach the cells. The more CO2 in the blood, the easier the O2 molecules jump off the cells where they are needed. This is called the Bohr effect.



Chapter 2: Oxygen uptake in rest and exercise – You might be surprised

The picture below illustrates several very interesting principles. Firstly, that  the oxygen level in the mitochondria is only one fourth of what is actually provided in the air. Secondly, that by ( anaerobic ) exercise the oxygen level in the blood increases, whereas in the cells where the oxygen is actually needed, it actually drops to almost nothing! (Richardson 2006)

Oxygen availability in rest and exercise

This means that no matter how much or how deeply you breathe, oxygen does not necessarily reach the cells. This is the reason why the cells retrieve energy from a process that creates acid instead. This has many unpleasant side effects, including our old friend – the DOMS.

An important reason why oxygen does not come out to the cells is the Bohr effect.

Hyperventilation, which naturally occurs during exercise (or ie. stress), removes CO2. Although the CO2 level rises in the veins (which transport blood away from the cells ), it drops in the arteries (which carry blood to the cells). And it is in the arteries we need the CO2. With too little CO2 in the arteries, the O2 becomes stuck on the blood cells. Oxygen instead runs around and around as a carousel without being used. (Sun 2001)

CO2 concentration during exercise O2 concentration during exercise

These are important hints that CO2 is not a waste product, but something that is vital and important to keep in mind. CO2 is the key to oxygen utilization. And therefore the key to increase the lactic threshold. It is also the key to effective elimination of metabolic acidosis and repair of muscle damage after exercise. And best of all, it’s free, always available, and you can control it yourself with your breath!


Chapter 3: The Lactic Acid Illusion – Are you ready to recover from it?

Here’s an interesting fact: the higher the CO2 (carbon dioxide ) tolerance, the higher exercise tolerance and endurance. The reason is that the higher CO2 levels in the blood, the more metabolic acidosis you can tolerate.

High CO2 gives higher lactate threshold

Researchers suggest using CO2 measurements to seek out the most promising athletic talents. They have seen that those with the highest CO2 in the blood also have the highest lactic acid threshold. (Bussotti 2008)

At the moment, there is still too few people who knows about the opportunity to increase the CO2 in the body via the breath.

Once this is known, even talents with low CO2 tolerance can easily be trained to make the most out of their talents . In addition, there is all the restorative properties that breathing exercise provide: the reduction of oxidative stress, increased blood circulation, increased production of new blood vessels, high blood levels, etc. All of this in addition to a greater tolerance to metabolic acidosis and a quicker recovery from acidosis after exercise.

The amount of CO2 is related to lactic acid. The more CO2 you have in your body, the less lactic acid you have.

Before we continue talking about lactic acid and exercise, this is important to understand: lactic acid is not a limiting factor of your exercise and not the main contributor of the burning sensation of acidosis. Lactic acid is in reality a buffer and protector from metabolic acidosis. The acidosis comes from other molecular processes. But lactic acid is still a good indicator of how much acidosis we have in the muscles since it increases linearly to the real metabolic acidosis. (Robergs 2004)

With proper use of breath after exercise, the CO2 can increase in a matter of minutes and lower lactic acid directly. (Avest 2010)

In addition, CO2 is a buffer against acidosis and makes the muscles last longer before reaching the lactate threshold. This has been demonstrated by divers who have developed a high tolerance for CO2. So even though we know that it is not the lactic acid that is the problem, we can still rest assured that by removing lactic acid we are actually lowering the metabolic acidosis.

CO2 is contained in the blood within a chemical equilibrium together with bicarbonate ( baking soda ) and carbon dioxide.

CO2 + H2O – > HCO3 – + H + – > H2CO3

These three molecules constitute the body’s pH buffer system. The larger the buffer we have, the greater tolerance to pH changes our bodies can tolerate. This includes a greater tolerance for exercise and metabolic acidosis, but also a greater tolerance for an unhealthy lifestyle which generally provides a more acidic pH in the blood.

How CO2 relates to lactate


Chapter 4: The Secret to Increasing Blood Flow – The Foundation of Recovery

For efficient recovery, increased blood circulation is essential. As a natural defense mechanism, the body’s blood vessels expand when we hold our breath (CO2 increase) so that oxygen and glucose can continue to distribute to the cells in the tissue and the brain. And of course, if we hyperventilate (CO2 decrease) the opposite happens, the blood vessels contract and the nutrient exchange is halted. (Gilbert 2005)

There are at least 3 different mechanisms by which CO2 increases local blood flow through our tissues (Varlaro 2007).

•CO2 increases the elasticity of arterioles and metarterioles, leading to vasodilation.

•CO2 relaxes smooth muscle fiber cells of the precapillary sphincters which increases the blood flow through the capillary beds.

•CO2 can enhance erythrocyes deformability which is an important ability for the blood cells to pass through the small capillaries and deliver oxygen to tissue far from the arterioles.

With the right breathing technique, CO2 is increased and blood circulation is increased everywhere in the body in just a few minutes. RecoveryBreathing is such a technique. You will discover that your body gets warmer and that heat flows out to the arms, legs, neck, face, and wherever blood circulation is increased.

Vasodilation means that the blood vessels expand. This is particularly important in the smallest blood vessels, the arterioles and metarterioles. These blood vessels control the blood flow through the capillaries, which are so thin that they only have room for one blood cell at a time. If the arterioles and metarterioles contract, blood flow through the capillary bed is severely limited and less oxygen and nutrients are delivered to the affected cells.

Especially circulation to the smallest nerve fibers are affected if blood flow through the capillaries are shut down. Over time this condition will make people more prone to chronic pain (neuropathic). This breathing exercise is valuable in recovery after training, but it might also be good to know about in any situation where the body needs to be repaired or need help to relieve pain and tension. Simply because blood flow is increased in the smallest blood vessels throughout all the tissues in our body from the smallest to the biggest. (Kolka 2013)

The key is to use your breathing to increase the CO2 in the cells, tissues and blood. To achieve this, the way is to breathe more slowly to preserve most of the CO2 in the body. Preferably 2-3 times a minute. It sounds complicated but is actually quite easy with the proper technique.


CO2 increases the level of NO in blood

CO2 augments the blood circulation because it widens the circumference of the blood vessels. CO2 does this by itself, but it also has a direct relation to NO (nitric oxide), which is the main vasodilator (expands the blood vessels) in the body. The more CO2 we have in the blood, the more NO is secreted by the blood vessel cells. (Fathi 2011)

NO allows the smooth muscle cells found in blood vessel, connective tissue and intestines, to relax, but it also has many other important functions in the body. This includes purifying the blood vessels from plaque, regulation of blood pressure, stimulation of the brain and extermination of  bacteria. The discovery of NO ‘s role in the body resulted in the Nobel Prize for Medicine in 1998. (Press release 1998)

Increased CO2 gives increased NO


Chapter 5: Your Most Abundant Antioxidant – Its Not What You Think

Oxidative stress is one of the major problems with exercise. And one major element in the DOMS process. The “stress” happens when the oxidation from spending oxygen goes beyond what the natural antioxidant defense can take care of. Thats when the oxidants start to damage the DNA, mitochondria and cell walls, and becomes a contributing factor to inflammation.

In addition to all the other positive effects of CO2 in the blood circulation, lactic acid neutralization, etc., the CO2 is also an antioxidant. And since CO2 is the direct result of oxygen metabolism, the CO2 is an effective antioxidant right where the oxidation occurs. In the heat of the moment. Its your friendly neighborhood superhero antioxidant! (Vesela and Wilhelm 2002, Kogan 1997, Kogan 1996, Croinin 2005.)

CO2 is a very small molecule that diffuses right through the mitochondrial wall, through the cell wall, through the tissue, and out into the blood. This happens by diffusion, i.e. that CO2 moves from one area with a lot of CO2 to an area with little CO2. If we take away too much CO2 from the blood, the CO2 in the cells will diffuse too rapidly into the blood so they do not get much work done as antioxidants.

However, if we retain as much CO2 in the blood as possible, the CO2 levels in cells will remain high so that they can make a greater effort as an antioxidant, instantly when the oxygen performs its destructive deed!



Chapter 6: Inflammation and How it can be Avoided

There are many studies looking at the relationship between CO2 and inflammation. Several studies in mice show that an increase in CO2 in the blood (hypercapnia) will reduce gene expression of inflammatory factors. This means that inflammation in the body is decreased.

It does not mean that inflammatory response is suppressed, as it is with COX-2 inhibitors and corticosteroids. It means that the body simply does not need to produce as much inflammation because of the protective mechanisms initiated by increased CO2. (Cummins 2010, Takeshita 2003)

In addition, several studies have confirmed that hypercapnia makes the neutrophils and macrophages (immune cells) secrete less cytokines (inflammatory factors). (Laffey and Kavanagh 1999,Curley 2011)

Therefore, by using the breath to increase the CO2 we get a strong anti-inflammatory effect, which is a particularly useful effect for us between workouts. Not least because the elite athletes are the major consumers of anti-inflammatory drugs such as aspirin and ibux.

Inflammatory markers in normocapnia vs hypercapnia


Chapter 7: Pain Reduction With Recovery Breathing

Many scientific studies shows how different forms of meditation influence pain sensations. The researchers often concludes that mindfulness meditation is the form that alleviates pain the most. The interesting thing about one study was that the scientists also looked at the frequency of breath. It turns out that mindfulness was also the meditation form where participants had the most slow breathing pattern. The breathing slowed down from 16 breaths per minute to 10 breaths per minute. Surprisingly, the scientists discuss whether it’s the breathing rate that gives the pain relief, and not necessarily the meditation technique by itself. (Grant and Rainville 2009)

This is a correlation, not a causation. But it is an interesting and an important factor that points towards the peripheral (meaning: not brain) physiological mechanisms for the pain reduction we experience when we breathe only 3 times a minute.

Heat tolerance Respiration Rate in Meditation

Scientists have also observed that when the CO2 levels in the body are low, eg. as a result of hyperventilation, the sensitivity of the nerves increase. Glutamatergic activity in the synapses (related to pain) is increased and the GABA -A activity (related to pain attenuation) is decreased. (Curley 2010, Fukuda 2006)

It’s simply easier to experience pain when there is less CO2 in the body. But the good news is that you can control the CO2 levels with simple breathing techniques, and instead you can get an analgesic effect. Just by using your breath!



By Chapter

The Oxygen Illusion

Beall 2007. Two routes to functional adaptation: Tibetan and Andean high-altitude natives 

Iscoe 2011. Supplementary oxygen for nonhypoxemic patients: O2 much of a good thing?

Massabuau 2003. Primitive, and protective, our cellular oxygenation status?

Hsia 2013. Evolution of Air Breathing: Oxygen Homeostasis and the Transitions from Water to Land and Sky

Laurino 2012. Mind-body relationships in elite apnea divers during breath holding: a study of autonomic responses to acute hypoxemia

Oxygen Availability in Rest and Exercise

Richardson 2006. Human skeletal muscle intracellular oxygenation: the impact of ambient oxygen availability

Sun 2001. Carbon dioxide pressure-concentration relationship in arterial and mixed venous blood during exercise 

The Lactic Acid Illusion

Bussotti 2008. End-tidal pressure of CO2 and exercise performance in healthy subjects.

Robergs 2004. Biochemistry of exercise-induced metabolic acidosis 

Avest 2010. Elevated lactate during psychogenic hyperventilation 

Blood circulation

Gilbert 2005. Better Chemistry Through Breathing: The Story of Carbon Dioxide and How It Can Go Wrong

Varlaro 2007. Carboxytherapy: effects on microcirculation and its use in the treatment of severe lymphedema

Kolka 2013. Treating Diabetes with Exercise – Focus on the Microvasculature

Fathi 2011. Carbon dioxide influence on nitric oxide production in endothelial cells and astrocytes: Cellular mechanisms

Press release 1998. The Nobel Prize in Physiology or Medicine 1998


Vesela and Wilhelm 2002. The Role of Carbon Dioxide in Free Radical Reactions of the Organism 

Kogan 1997. Carbon dioxide–a universal inhibitor of the generation of active oxygen forms by cells (deciphering one enigma of evolution) 

Kogan 1996. Ability of carbon dioxide to inhibit generation of superoxide anion radical in cells and its biomedical role

Croinin 2005. Bench-to-bedside review: Permissive hypercapnia


Cummins 2010. NF-κB Links CO2 Sensing to Innate Immunity and Inflammation in Mammalian Cells

Takeshita 2003 Hypercapnic Acidosis Attenuates Endotoxin-Induced Nuclear Factor-B Activation 

Laffey and Kavanagh 1999. Carbon dioxide and the critically ill—too little of a good thing?

Curley 2011. Can ‘permissive’ hypercapnia modulate the severity of sepsis-induced ALI/ARDS?

Coakley 2002. Ambient pCO2 modulates intracellular pH, intracellular oxidant generation, and interleukin-8 secretion in human neutrophils

Wang 2010. Elevated CO2 selectively inhibits interleukin-6 and tumor necrosis factor expression and decreases phagocytosis in the macrophage

Pain Reduction

Grant and Rainville 2009. Pain sensitivity and analgesic effects of mindful states in Zen meditators: a cross-sectional study

Curley 2010. Bench-to-bedside review: Carbon dioxide

Fukuda 2006 Moderate hypercapnia-induced anesthetic effects and endogenous opioids.

9 thoughts on “The Science

  1. I really like what you are doing with this. There’s a lot of good, solid information. However, the manner in which you transitioned between explanations was a bit hard to follow. If you could transition between, explain your jumps, I could follow more easily. (This my way of asking you to because what you’re talking is seriously cool, I have a science background to understand, but can’t make all your slight subject hops. Also if you explain the between parts, I bet people without a science background could understand too, if that’s what you are going for.)

  2. Thanks a lot for your feedback! Yes, I know Im writing a bit too sciency and unconnected. I am not an exercice phyiologist and have spent a lot of time getting a grip on the science that can confirm the results from this breathing practice. I was impatient to make it available to more people. Thats probably why it jumps from one topic to another. The science background is pretty much finished now and I keep writing to make it more available for non-sciency people also, so there will be some changes. This topic and information deserves all the attention it can get. From all the people that can “get it”.

    Im grateful for your feedback and very happy that you like the information! I hope you have many good experiences with the practice.


  3. Hello Marius,
    I was wondering, should I keep the ratio of breathing 1-1-2 so instead of 5-5-10 I go 10-10-20? I don’t feel the warm of of my muscles otherwise. I’ve been practicing box breathing and other breathing exercises for a while now. I was wondering if that ratio can just translate easily like that.
    Great article and Thank you so much for publishing it!

    • Hello! Thank you for your question 🙂
      I believe the whole point is the relaxed pause after exhalation. So if you are able to keep the pause for longer than 10 seconds, just go for it. As long as it is relaxed. And as long you are able to keep a steady pace for 10-20 minutes without the need to take deep breaths inbetween. I would rather go for a ratio like this: 5-5-20. If you do longer (or deeper) inhalations you might cancel out the CO2 increase we are looking for. Just focus on the pause, and keep it for as long as it is comfortable and dont create any muscular tension. But anyway you do it is fine! If you get the warm feeling of increased bloodflow, you probably feel the effects of increased CO2 levels. Thats the whole point 🙂
      Good luck! And dont hesitate to ask you have any more questions.


  4. Some of these ratios I’ve read on here are a bit confusing as the ratios I’ve always been given were structured differently. So take a box, you have 4 numbers.

    #,#,#,# representing inhalation, hold, exhalation, hold….. respectively

    Using that framework you’re recommending something like this?: 5,5,10,10?

    • Hello Matt.

      Thank you for your question 🙂 If you take your box-example, the breathing practice I recommend here is: 5,0,5,10. Only hold after exhalation. This way is the quickest to increase CO2 levels in the blood, which is the main target here 🙂

      Best regards,

  5. Hello,

    I’m really happy to have found someone interested in this topic and who did such a great job with reading and explaining this part of the science of the breath. Thank you;
    I would like to translate your article in french and use bits of it for my training method for athletes. I already have found all this infos here and there but I think your article gives a global perspective .
    Can I do that ?


    • Thank you 🙂 Feel free to use anything you want from my site. It would be nice if you credit my work if you use a lot of it, but its not a demand. I am not actively teaching, nor do I feel any ownership of this knowledge, so do what ever you want with it. I am only happy the knowledge spreads since it is so useful, especially for athletes 🙂

      Best regards,

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