Some physiological effects of Pranayama

Pranayama

Pranayama is a practice of controlling and modifying your breath. Since this is a deviation from "natural" uncontrolled breathing, it has effects on the gases in the blood and also on pressure inside the lungs and abdominal area. In this post, we briefly describe these effects.

These notes were written in the course of taking a class from Andrey Tkachenko. I highly recommend his Pranayama and meditation classes (https://tkachenkoyoga.com/) to everybody who is interested in these topics (and speaks Russian).

CO2 effects

Oxygen from respiration diffuses into the blood and binds to hemoglobin in red blood cells. Oxyhemoglobin transports oxygen to cells, where it undergoes the Krebs cycle, producing new molecules (like ATP) to store energy and generating CO2. Most of the energy produced is utilized to restore the electric polarization of cell membranes and synthesize proteins. This polarization is crucial for neuron signaling, hormone balance, and muscle contraction. CO2 dissolves in blood, forming carbonic acid. Reactions occur, producing H+ ions. The higher the CO2 levels, the more H+ ions are present, resulting in a lower pH. The normal pH range is 7.37-7.45. A lower pH indicates acidic fluid, while a higher pH indicates basic fluid. The body regulates pH by adjusting breathing, which alters CO2 levels in the blood.

Changes in CO2 levels have various effects. Decreased CO2 (increased pH) stabilizes oxyhemoglobin, inhibiting oxygen delivery to cells. Increased CO2 facilitates oxygen delivery to cells and relaxes blood vessel walls, enhancing blood flow to organs and reducing the workload on the heart. Conversely, decreased CO2 causes blood vessels to constrict, increasing blood pressure and necessitating a faster heart rate.

An increase in CO2 above normal levels is hypercapnia, while a decrease is hypocapnia. Hypercapnia enhances oxygen delivery to organs and increases blood flow, but it triggers a reflex to breathe faster. Training is necessary to tolerate hypercapnia and induce hypoxia (decrease of oxygen delivery to the cells). One can reach 80% of oxygen safely, but lower levels are dangerous. Hypoxia has many many positive affects and reaching it constitutes the essence of pranayama and modern practices like Wim Hoff and holotropic breathing.

Hyper and hypo ventilation

To understand how one reaches hypoxia, we need to understand the effects of modulations of natural breathing. Let's define the following variables: v = volume of air in liters per breath, N = number of breath cycles per minute. This defines the volume of air going through the lungs in one minute V = v * N. The relationship of actual V compared to normal breathing defines hyperventilation and hypoventilation.

In the normal state v = 0.5. Very deep inhalation adds 2.5, very deep exhalation adds 1.5 (these values, as well as other parameters in the examples below are average and can vary depending on a person and person's experience). Lets consider a sample of popular practices:

1. Normal state: v = 0.5 N = 15 V_NORM = 7.5

2. Full yogic breath: v = 4.5 N = 3 V_F = 13.5

3. Kapalabhati v = 0.5 N = 60 V_K = 30

4. Abdominal bhastrika v = 1.5 N = 60 V_AB = 90

5. Chest bhastrika v = 2.5 N = 60 V_CB = 130

6. Full bhastrika v = 4.5. N = 60 V_FB = 270

7. Wim Hoff v = 4.5 N = 20 V_WH=90

8. Vi Samavritti 1:3:2:1 with 1 being 10 sec; N = 0.86, v = 4.5. V_S = 3.87

9. Viloma with 5 steps (19 intervals) each 5 sec; N = 0.63, v = 4.5. V_V=2.8

If V is smaller than V_NORM, hypoventilation occurs, while if V > V_NORM, hyperventilation occurs. Practices 2-7 result in hyperventilation, while 8 and 9 result in hypoventilation.

Hyperventilation and hypoventilation affect O2 and CO2 levels differently. Hyperventilation increases CO2 elimination (O2 is already close to max and in general varies much less than CO2) and narrows blood vessels (due to decreased CO2), leading to hypocapnia, which stabilizes oxyhemoglobin and thus hinders oxygen delivery to tissues (and also often leading to increased heart rate). The lowed levels of CO2 full the breathing center (it associate the need to inhale with higher levels of CO2) and that it why it is easier to retain breath after hyperventilation practices. The same mechanism explains why it is harder to hold breath after exhalation then after inhalation (after exhalation, the CO2 level is lower and it takes breathing center shorter period of time to start acting). Quite often, in pranayama, one does some hyperventilation practice before holding the breath on exhale or inhale. In some sense, hyperventilation in pranayama is done only to make hypercapnia more accessible.

Hypoventilation increases CO2, leading to hypercapnia. In an untrained person, it triggers the breathing center to command inhalation, and this prevents a person from hypoxia (hypoxia is when O2 is lower than 90%) so that the level of O2 almost does not drop. This means that an untrained person after hypoventilation will tend to be in a normal O2 state and hypercapnia.

Relaxation techniques can train the body to tolerate hypercapnia, fight the imperative to breathe, and reach deep hypoxia, beneficial for enhancing many physiological functions. For example, if you do vi-samavritti in proportion 7:28:14:7 (in seconds). Thus, the working state of pranayama combines hypercapnia and hypoxia. It is hypoxia actually that brings all the wonder results of modulating the breath. But one has to go through hypercapnia first and be able to tolerate it and reach hypoxia. Controlled hypercapnia has benefits by itself: one can fight asthma (which manifests due to the lack of CO2 and consequent inability to deliver O2) or make yourself warm.

Pressure effects

The pressure deviations are considered compared to the "neutral" state. One can reach this state by first gently inhaling and then gently unforced exhalation and pausing in this state with the open throat and mouth and all diaphragms relaxed. The pressure in the lungs will be equal to the atmospheric pressure.

Once you increase the pressure in a particular area, this will push out all liquids from there and vice versa. And the decreased pressure will attract fluids there. Using different breathing techniques, one can move blood and other fluids in the body.

Inhalation is performed by moving the abdominal diaphragm down (increasing the pressure in the abdomen) and expanding the rib muscles to decrease the pressure in the chest and let the air in. The particular effects of various breathing practices and stomach manipulations depend on many variables: the scale of movements of the ribs, the scale of movement of the stomach, and the use of bandhas. For example, if one inhales and expands the ribs a lot, the diaphragm will move less. If one uses mula bandha, this restricts the movement of the abdomen down and generally increases the pressure in the abdomen.

During the exhalation one pushes the ribs in to increase the pressure in the chest and push the air down. The diaphragm returns to neutral but we typically push the stomach in, so both pressures grow.

If one restricts the inhalation (Ujjayi breath and Kaki mudra), this makes the decrease of the chest pressure even more pronounced. If the restriction is strong, the abdominal pressure will also decrease! If one restricts exhalation, the pressure in both volumes will significantly increase. So many practitioners use restriction only on inhalation.

Uddiyana is reached by creating low pressure in the chest so that one can pull the diaphragm in, which decreases the pressure in the stomach. The pressure falls strongly in both volumes. That is why this bandha brings lots of blood into them. This can be used if one feels pressure in their head or stiffness in the legs and performs Uddiyana to reduce them. A similar, but weaker effect is reached through breath retention on exhalation.

When we do stomach bhastrika, the chest pressure falls (as always on inhale) and we push the stomach forward, so the pressure there also increases. In exhalation, the chest pressure increases and, since we push the stomach in, its pressure is also elevated.

With the chest bhastrika, the stomach pressure does not change much, but since the diaphragm still moves, the pressure slightly increases on inhalation and falls on exhalation.

In the following table, I present just the common patterns. I use 0 for the neutral state, + and - for increased and decreased pressure, respectively.

	Chest pressure	Abdomen pressure
Inhalation	-	+
Exhalation	+	-
Restricted inhalation	-	-
Restricted exhalation	+	+
Uddiyana	-	-
Breath retention in inhalation (open throat straight back)	0	0
Breath retention on inhalation (closed throat sunk posture	+	+
Breath retention on exhalation	-	-
Inhalation in chest bhastrika	-	+
Exhalation in chest bhastrika	+	+
Inhalation in stomach bhastrika	-	+
Exhalation in stomach bhastrika	+	+
Inhalation in full bhastrika	-	+
Exhalation in full bhastrika	+	+

Positive effects of transient hypercapnia and hypoxia

Hypercapnia and hypoxia are reached through slowing the air intake (by controlling the breathing rate, closing the vocal cords, and breathing only through the nose) and, naturally, through full breath retention. Such transient practices train the body (while prolonged states are harmful). In fact, pretty much any training involves controlled transient stress. This hypercapnic/hypoxic and breath retention lead to:

• Increased delivery of O2 to organs and brains

• Increased production of the growth hormone

• Increased glucose tolerance

• Mitachondria training/selection process (the weak ones die, the strong ones become stronger and they even create large clusters, thus making the system of generating energy from oxygen more efficient). When mitachondria has mutations, they fix themselves by cutting out the damaged parts from their circular DNA. In stable conditions or when the physical activity is low, such cells with smaller DNA multiply faster then the ones with better DNA. If we stress mitachondria, the weak ones parish faster. It is hard to stress mitachondria in brain using physical activity, but the intermittent hypoxia accomplishes this.

• Creation of more red cells by spleen

• Stronger immune system and faster healing (due to increased formation of capillaries delivering everything that is needed)

• Slower cognitive decline (due to better cerebral flow)

• Learning how to effect your energy level and emotional states.

So in order to reach these effects, one needs to practice being in hyperpnia and hypoxia. One can practice with the following sequence: start with hyperventilation (use practices 1-7 listed above) to make hypercapnia tolerable. Next one inhibits breathing by retention of breath (on exhale and next on inhale). Next one can do some cyclic breathing (practices 8 and 9).