The name “Bohr” usually evokes one of the fathers of quantum mechanics, the famous Danish physicist Niels Bohr, who among other things enunciated the so-called complementarity principle, emphasizing the presence of dual aspects in our way of interacting and observing reality. Few know, however, that Niels’ father, Christian, was a physiologist, and that in 1904 he discovered an important effect underlying the physiology of breathing, which today bears his name, highlighting a somewhat paradoxical relationship between lung ventilation and oxygenation of the organism.
Practitioners of respiratory techniques certainly have an interest in knowing the Bohr effect, and other effects related to it, but I realized that it is rarely the case, even among experts, which gave me the stimulus to write this note. Let me start by saying that I am not a physiologist. What I am going to expose is therefore to be taken into consideration only in indicative terms, as an invitation to deepen the decidedly complex theme of human respiration.
More than thirty years ago, I approached a practice known today with the term of rebirthing, which uses intense breathing, without pauses, similar to the circular breathing of Yoga, of which we find traces in texts such as the Bhagavad Gita and the Vigyana Bhairava Tantra, and in traditions such as the Sufi. It is only a partial similarity, however, as the yogic circular breathing (little known also among Yoga practitioners) is an active procedure, perfectly balanced and controlled, both for the duration and uniformity of the breath and for the management of the (explosive) passage between the two respiratory acts, with the air passing only through the nose, using the Ujjayi technique, while the breathing used in rebirthing (also called “circular”) usually takes place in an irregular and rather unbalanced way, without a predetermined rhythm, mainly through the mouth and with an attitude of the practitioner which is predominantly passive, which can lead to a possible lowering of his natural energy defenses, therefore also opening to possible negative “subtle” influences (of course, this is not a problem if the environment in which you practice is “energetically clean,” but how many operators are able to guarantee this?).
Regardless of these important differences (in any case, this is not the topic of my article), both the very well-structured circular breathing of Yoga, and the decidedly much more chaotic breathing of rebirthing, promote a condition called hyperventilation, during which the practitioner greatly increases the frequency and intensity of her/his respiratory acts, while keeping the body at rest. More precisely, the term “hyperventilation” refers to a condition where you breathe more than necessary, taking into account the metabolic demands of the moment. This triggers a whole series of physical symptoms, which can occur for a more or less long time, including, just to name a few: stiffness and muscle contractions (tetany, myoclonus), intense tingling, altered sensitivity of the limbs (paraesthesia), portions of the body perceivable as swollen, dilated, or compressed (dysesthesia), cardiac arrhythmias, to which are added effects on the cognitive level, for example, states of vertigo, dizziness, mental confusion, sometimes anguish and panic, or short voids of consciousness, but also deep energetic and emotional releases, conditions of increased lucidity, well-being, expanded consciousness, extracorporeal states, etc.
There would be much to say about all these phenomena, their degree of permanence and their modulation based on the practitioner’s psychophysical state and experience. Here I open only a brief parenthesis to observe that everything we perceive with clarity is usually attributed to phenomena that take place at the physical (“dense”) level. But it’s not always like this. Many of the phenomena we perceive occur between the “dense” and the “subtle” and it is not always easy to distinguish which perceptions come from which level. The breath, among other things, constitutes one of the most “subtle” forms of energetic mobilization that we are able to control with our soma. In this sense, physiological breathing constitutes a sort of “last frontier” which is still easily perceivable and accessible through our ordinary senses, beyond which dimensions of an extraphysical nature (the existence of which I will take here for granted), the domain of manifestation of our more “subtle” consciential (para-material) vehicles. For example, if we perceive an intense vibration propagating up and down through the body, this could originate from alterations of the nervous and/or circulatory system, but could also find its origin in energy variations taking place in the so-called etheric double, the connection matrix between the physical body and the rest of our “holosomatic machine.” In other words, respiratory techniques, especially if practiced with full presence and awareness, allow not only to act on our biology (in particular on the brain and nervous system), but also on the interface between the physical and the extraphysical, on those consciential energies (indicated by the term of prana in Yoga) which are at the foundation of our manifestation.
Taking into account the above, it is certainly important to know what happens at the physical level when we act through certain techniques, here of a respiratory kind, not only to better understand the reasons behind these procedures, and then correctly interpret the phenomena we experience, but also to better demarcate the perceptions of physical origin from those of extraphysical origin. Now, when years ago I practiced rebirthing for the first time, and in the following years also other techniques of intensified breathing, such as the aforementioned circular breathing of Yoga, or the kapalabhati pranayama, the explanation I gave myself, and which I often received, is that many of the physical phenomena that I could experience in the course of the practice were the result of a process of hyperoxygenation. This idea was also comforted by the observation that at the end of a cycle of breathing it was possible to experience a natural and prolonged suspension of breathing, that is, an absence of the need to breathe that could last for several minutes. Why did this happen? The answer I gave myself at that time (and which I naively gave myself for a long time) is that circular breathing, with its intensity, was able to load the whole organism deeply with oxygen, well beyond what could be obtained with natural breathing, from which followed the possibility of then suspending the breath for a long time without fatigue.
Nothing is more wrong. In fact, already with the natural breath, our blood and our organs are oxygenated in an almost maximal way. This is because the proper functioning of our body requires the percentage of oxygen-saturated red blood cells to be between 95% and 99%. This saturation takes place by means of hemoglobin, the red-colored metalloprotein contained in the blood cells and responsible, in fact, for the transport and distribution of molecular oxygen to the tissues that need it (oxygen is collected in the pulmonary alveoli and carried by the arterial flow). It is important to specify that the amount of dissolved oxygen in the blood plasma represents only about 2% of the total oxygen contained in our blood, which for more than 98% is transported by hemoglobin. This is precisely the role of hemoglobin: to increase the ability of the blood liquid to carry oxygen by almost a factor of 100. Therefore, breathing more intensely does not allow us to significantly increase the overall oxygenation rate of our blood, as this rate is mainly determined by the saturation of red blood cells, which is already close to 100% in standard breathing conditions.
But there is more. The perceived need to breathe is not determined by a drop in the level of oxygen in the blood, as you would intuitively expect, but mostly by the level of carbon dioxide. The level of oxygen, and other factors such as the emotional state of a person, certainly come into play, but it is the level of carbon dioxide that mostly controls respiratory dynamics. Recall that breathing, at the physical level, essentially promotes exchange between two important gases: oxygen and carbon dioxide. The first is introduced into the body through inhalation and is transported by the circulatory system to every cell in the body, then exchanging it with the second, which is a waste of the cellular metabolic activity, which is eliminated through exhalation. Now, as I said, the brain’s respiratory center regulates the respiratory rhythm on the basis of numerous mechanisms, but the most important is chemical in nature and has to do with measuring the rate of carbon dioxide in the blood. The more the intensity and frequency of breathing increases, the greater the elimination of carbon dioxide from the blood. This “decarbonization” will ensure that the respiratory center, by detecting a reduced presence of carbon dioxide in the blood, will not go towards promoting those muscular and/or diaphragmatic contractions that we usually perceive when we feel “air hunger,” ending up triggering the breathing.
This explains why hyperventilation is very dangerous to practice before a dive. In fact, by delaying the attainment of that carbon dioxide threshold that informs the central nervous system of the need to breathe, it also delays our perception of this need, so much so that a freediver may find herself/himself in the condition in which, without knowing it, her/his oxygen level has fallen below that break-point which leads to the so-called hypoxic syncope, that is, to a (momentary) loss of consciousness due to a lack of oxygen in the brain. This is usually fatal if it occurs when the freediver is still underwater. On the other hand, in case of prolonged suspension of breath after a circular breathing cycle, if the practitioner is comfortably seated or lying down, the possible occurrence of a blackout will not represent any danger. In fact, our breathing is carried out even without the need for conscious control, therefore, in case of fainting, it will resume its course completely automatically.
Let me come now to the key point of my note on the physiology of breathing. What happens when we hyperventilate? We have just seen that the level of carbon dioxide in the blood drops significantly and that the oxygenation rate, on the other hand, does not increase significantly. In addition to this, something quite surprising happens: hyperventilation, instead of producing a cellular hyperoxygenation condition (as I mistakenly thought years ago), it produces its exact opposite, a condition of hypoxemia (decrease of available oxygen), and this for the reasons I’m going to illustrate. First of all, a massive removal of the carbon dioxide dissolved in the blood produces its alkalization, i.e., the blood pH increases, a condition called respiratory alkalosis. Carbon dioxide being a vasodilator, a reduction in its concentration (called hypocapnia) produces vasoconstriction, therefore a reduction in the flow of blood to the various tissues, including the brain tissues, which partly explains the confusional states, dizziness, and other symptoms which I mentioned. Respiratory alkalosis also causes an alteration of the electrolytic balance of the blood. Without going into details, this leads to a temporary reduction in the concentration of calcium (hypocalcaemia) and since calcium has a determining role in the transmission of the impulses of the nervous system, this produces greater excitability of neurons and muscle fibers, hence those symptoms such as: tingling, paraesthesia, muscle stiffness, spasms, myoclonus, etc.
But that’s not all. On top of that, there is the so-called Bohr effect, which I mentioned at the beginning of the article. What Christian Bohr (and colleagues) discovered at the beginning of the last century is that the efficiency of oxygen release by blood cells varies according to its pH. In other words, it is one thing to have the blood loaded with oxygen and another thing is to make it available to the organs and tissues of the body. As we have seen, the first effect of hyperventilation is that of vasoconstriction induced by the increase in pH (alkalosis). But a second, no less important effect (the one discovered by Bohr) is that the increase of the pH of blood inhibits the release of oxygen by hemoglobin. The blood may then well be loaded with oxygen but will release it to the various organs with extreme difficulty. The usefulness of this effect is easy to understand. When we exercise, there is a greater demand for oxygen at the cellular level. This same activity will produce metabolic waste, such as increased production of carbon dioxide (and lactic acid), which by acidifying the blood will increase the release of oxygen by hemoglobin. In the situation of a person practicing a hyperventilation breathing technique, however, there is no increased production of substances capable of altering the pH of the blood, which therefore will remain alkaline; hence, hemoglobin will have difficulty releasing its oxygen, which will only be minimally transferred to the different tissues.
Moral of the story, when you breathe with greater intensity and frequency, without this being the result of an increased physical activity (hyperventilation), exactly the opposite occurs of what once, naively, I thought happened: there is a decrease instead of an increase of the oxygen actually available in the blood and a concomitant reduction of blood flow, due to the effect of vasoconstriction, therefore a lower oxygenation in general of the different tissues, including the brain. In other words, when you practice “increased breathing” as in the circular breathing of Yoga, you obtain a temporary state of hypoxia, that is, hypo-oxygenation, which among other things will lead to a general lowering of the brain activity.
At this point, I should talk about a whole series of other phenomena induced by the chemical variations of the blood, such as the release of certain neurotransmitters that favor the production of particular mediators, which in turn act at different levels in the brain, allowing the release of endorphins, that is, of “endogenous opioids” with numerous functions, such as pain control, stress management, sponsorship of states of well-being, of euphoria, etc. But the point I wanted to make with this note of mine is another. On the one hand, I simply wanted to correct an insidious, and apparently widespread, error, which consists in thinking that by breathing more you can easily “get drunk with oxygen,” when exactly the opposite happens (see also, on that subject, the work of the Ukrainian doctor Konstantin Pavlovich Buteyko). On the other hand, I wanted to bring attention to an aspect that is important to understand and to deepen, for those who use pranayama to facilitate access to “augmented” states of consciousness.
Simplifying the discussion, we can say that to access non-ordinary states of consciousness it is necessary to activate a non-ordinary mental activity, and to do so a natural strategy consists in lowering the volume of the ordinary mental activity, promoted by the electrochemical processes of our physical brain; an activity in which we often find ourselves deeply identified. In other words, we need as much as possible to put our brain to rest, while at the same we have to try not to put also our mind to rest (whose activity is then supported by processes taking place in more “subtle” paracerebral structures). Now, to temporarily reduce our brain activity, by using breathing, there are essentially two ways to do so: that of hypoxia and that of hypercapnia. To promote hypoxia (obviously only a temporary one), as we have seen, it is necessary, paradoxically, to increase our lung ventilation. To obtain hypercapnia, which corresponds instead to an increase in carbon dioxide concentrations, pulmonary ventilation must be reduced as much as possible, i.e., we have to promote a state of hypoventilation, which will thus promote a narcoleptic state (leading again to a reduction in the brain activity).
To this end, in Yoga there are breathing techniques that include periods of prolonged suspension of breath, between the phases of inhalation and exhalation. For example, in the so-called samavritti pranayama, the practitioner obtains (among other things) a slowdown of brain functions by producing two apnea phases of equal duration at the inhalation and exhalation phases (hence the alternative name of square breathing, often given to this pranayama): a retention phase between inhale and exhale and a suspension phase between exhale and inhale. The whole procedure increases its effectiveness to the extent that the practitioner, with experience, is able to extend the duration of these phases. It should be noted that hypercapnia being produced in a gradual way, cerebral hypoactivity is promoted without danger for the neurophysiology of the brain.
Concluding this excursus of mine, I stressed that when we breathe naturally our body is already oxygenated in an almost optimal way (in the absence of physical or mental disorders, of course) and our blood maintains a carbon dioxide rate below the toxicity threshold, whose variations allow us to better regulate oxygen absorption according to metabolic needs. When, on the other hand, we artificially promote a departure from this natural respiratory condition, we can easily promote a temporary and partial inhibition of our brain processes, which can thus favor access to cognitive functions associated with our more “subtle” vehicles of manifestation. Some of the breathing techniques of Yoga exploit this possibility inherent in our physiology to their advantage (of course, they are not limited to this). In the case of circular breathing, hyperventilation induces a state of hypoxia, while in the case of square breathing, hypoventilation promotes a state of hypercapnia. In both cases, our monkey brain partially goes to sleep and for a few moments, we can distance ourselves from its great hypnotic power, while at the same time we can try (which is not easy) not to lose our mental lucidity.
I end with a warning. Breathing is a very complex process. It certainly is with regard to its biochemical aspects, still not fully understood today. For example, if it is true that hyperventilation produces hypoxia, it is also true that a phase of prolonged suspension of breathing, following a cycle of hyperventilation, is apparently capable of producing deep oxygenation of our tissues. This can be verified by carrying out the largest possible number of push-ups immediately after a hyperventilating cycle, remaining in apnea during their execution (only breathing if strictly necessary). We can then observe that we are able to perform a far greater number of push-ups than usual. But the complexity of our respiratory processes is also due to their action on the more “subtle” levels of our anatomy and physiology. Therefore, altering our natural breathing, in the context of very intense practices that are protracted over time, is something that must be done only in full knowledge of the facts, otherwise, we run the risk of creating deep imbalances, not only physical but also energetic, emotional and mental. A powerful tool like breathing must be explored with great prudence, discernment, and awareness, and initially always with the help of more experienced practitioners. In other words: cum grain salis!
For the Italian version of this story, go to: Sul “paradosso” dell’iperventilazione