Pranayama is very popular these days, and, I suspect, often wrongly taught. Although many teachers use that famous quote from the Hatha Yoga Pradipika:
"Just as lions, elephants and tigers are controlled by and by, so the breath is controlled by slow degrees, otherwise it kills the practitioner himself",
It seems that they disregard - or their students disregard - this advice almost from the start.
The reason I say this is comparing what I see now to what I was originally taught. Back in the 70s, before walking to Rishikesh, I stayed in an ashram in Haridwar. I am not going to pretend I sat at the feet of enlightened gurus, nor did I have to sit for months at a gate before being admitted, but strolled into what seemed a deserted courtyard. I was eventually approached by a wild-looking man who beckoned me to sit down and show him alternate nostril breathing. This was some kind of test for acceptance into the ashram. He seemed reasonably satisfied with my effort. He then signalled for me to pay attention, and blocking off one nostril started inhaling - or what I assumed was inhaling: the breath was totally silent and lasted what seemed a very long time. He then did Jalandhara Bandha for considerably longer and finally released the throat lock and exhaled, also completely silently. The whole round must have taken over 5 minutes. And so began my first lesson in Pranayama.
Now the yogis, contrary to popular western ideas, are very keen on measuring everything possible. One of those measurements is how far the breath moves to and from the nostrils. They have recorded typical lengths for a range of activities. This can be done by observing when a fine thread of cotton no longer moves when held in front of the nose. The ultimate aim is for the breath to remain within the nostrils; in other words, to become imperceptible. My teacher used another method: every few days he would lick the palm of his hand and hold it close to my nose as I exhaled. One can easily feel the cooling effect of the breath on the hand. It took me some time until his hand was touching the tip of my nose.
The cessation of movement of the breath is called Kumbhaka. This has to be practised very, very gradually. It should be acquired by a gradual diminishing of the distance covered by the movement of the breath in exhalation as well as inhalation. So what exactly is Kumbhaka? Is it just very, very quiet breathing, or is it breath retention? Is there a difference? What do the yoga texts say about it?
The Sutras of Patanjali
2.50 "Exhalation, inhalation, retention, technique, time and number must be very precisely regulated over a lengthy period"
2.51 "The fourth pranayama technique ultimately transcends breath retention after exhaling and inhaling"
The Bhagavad Gita
4.29 "Some others offer the outgoing breath to the incoming breath and the incoming breath to the outgoing breath"
Hatha Yoga Pradipika
2.73 "In the practice of Kevala Pranayama, when it can be performed successfully without Rechaka and Puraka, then it is called Kevala Kumbhaka
This fourth breathing state transcends the first three well-known phases of breath puraka, kumbhaka, and rechaka, and is the sought-after divine state of Kevala Kumbhaka. The sentence depicts the two gross breaths becoming one, as if the breaths neutralize each other, thus they stop. This is the first stage. The two outer gross breaths go away, but are then found and enjoyed within a subtle form. So the two breaths still exist. Then even these are ‘offered into each other.’
This is a tantalizing idea. The breath is transformed from the gross movement to the subtle movement of prana. It is as if it has been refined and refined until its essence - prana - is what remains. Is this the true Kevala Kumbhaka?
Let's keep this real. In my experience, when the breath becomes imperceptible, it actually feels as if it has stopped, but it is a very different sensation to just holding the breath. And of course, it hasn’t stopped. Instead of feeling that panic sensation of forcing breath retention, this produces a deep calm, a stillness in both body and mind. And what about the ‘buried alive’ experiments? Some have been rigorously investigated and it appears that yogis have slowed down their metabolism so they can live on the little air they have been buried with.
This suggests that if Pranayama is to be practised, the breath first and foremost must be refined until it is almost invisible. What is actually happening physiologically during quiet breathing or breath retention?
Is Carbon Dioxide the Answer?
Carbon dioxide is a byproduct of the energy-generating chemical reactions occurring within the cells of the body. CO2 diffuses into the blood and is transported to the lungs where it is eliminated in exhaled air. But carbon dioxide is not just an inert waste product. It is also a vital component in the maintenance of the chemical environment of the body, because it also regulates the pH of blood, as well as other fluids outside and inside each cell of the body. Regulation of acidity and alkalinity within the tissues of the body is extremely important. Blood is slightly alkaline with a pH = 7.4, while the insides of cells are slightly acid with a pH = 6.9. The body’s homeostatic mechanisms ensure that pH is maintained within strict limits.
CO2 is a potent vasodilator, and an increase of in the inspired air is known to cause a number of vascular changes in the brain including increased cerebral blood flow, cerebral blood volume, as well as higher and concentrations in the blood. Carbon dioxide in concentrations of 5-7% produces an increase in cerebral blood flow averaging 75%. Inhalation of high oxygen produces a significant decrease of 13% in cerebral blood flow and no change in cerebral oxygen consumption.
Hypercapnea - increased in the blood - has also been shown to reduce metabolic activity in the brain. If the brain is in a high arousal state (e.g., conversation, thinking), the EEG power spectra show a relative increase in higher frequencies, whereas if the brain is in a low arousal state (e.g., relaxing, drowsy, sleepy, day dreaming) lower frequencies predominate. During hypercapnea, the brain's electrical activity resembles lower arousal states. Overall, CO2 has a suppressive effect on brain activity. The use of CO2 has had a long and varied history. A 1957 article from the American Journal of Psychiatry, remarks upon its "favorable effects in a variety of neuroses and psychosomatic conditions, especially in anxiety states, phobic reactions, certain ill defined tension states, and conditions like spastic colitis and migraine headaches”. They further added “CO2 narcosis therapy may thus be considered an important method of treatment for various types of neuroses and psychosomatic conditions. In many cases it is of therapeutic benefit by itself, but usually it is most effective when integrated with psychotherapy”.
What happens if we do the opposite and decrease CO2 in the blood? When we hyperventilate by breathing very fast, we lose CO2 but we cannot actually absorb excess oxygen. What it does is induce hypocapnea – decreased CO2 in the blood. And this has profound consequences. Contrary to what you might expect, over-breathing leads to vasoconstriction, and thus to potentially serious deficits of oxygen (hypoxia) and glucose (hypoglycemia). It also triggers constriction of other smooth muscles, e.g., in the bronchioles and the gut, thus potentially exacerbating both asthma and irritable bowel syndrome.Another consequence is through the Bohr Effect, whereby haemoglobin’s oxygen binding capacity is inversely related to carbon dioxide concentrations. As concentrations in the blood drop, oxygen is bound tighter to the haemoglobin. Over-breathing paradoxically results in decreased cellular respiration even if the blood may be carrying significant quantities of oxygen.
Putting it into Perspective
The above descriptions illustrate how important CO2 is to brain metabolism. Increasing CO2 in the blood leads to higher cerebral blood flow, higher oxidative metabolism, and lower arousal states. Decreasing CO2 leads to decreased cerebral blood flow, and higher states of arousal.
So what is happening if we breathe very softly as described earlier? Quiet breathing using only the diaphragm to breathe (belly breathing) shifts the CO2/O2 balance slightly in favour of CO2 and induces a mild hypercapnea. Anyone practising quiet breathing will notice a sense of peace and inner calm combined with increased alertness, as a direct consequence of increased levels of CO2.
Apart from quiet breathing there are other ways to increase levels of CO2:
Practising breath retention leads to increased tolerance to , although there are limits. Extreme levels of have an anaesthetic effect and will depress and ultimately abolish the activity of the respiratory control centres. This cessation of breathing will lead to loss of consciousness, which isn’t really the aim in yoga.
Breathing against a resistance
The Buteyko method - used to manage asthma - entails breathing through the nose rather than the mouth, therefore introducing some resistance, using the diaphragm rather than the chest, and breathing very quietly, all of which will be familiar to anyone practicing yoga. Ujjayi Breathing - Ujjayi breathing is a classic breath technique used in meditation, and provides a mild resistance to breathe against.
Alternate nostril breathing. Whatever may be thought of its advantages, it certainly will increase the resistance to breath and produce a slight shift in CD.
It’s no coincidence that many of the breathing techniques of yoga are aimed at increasing levels of CD, leading to conditions very favourable to meditation. The question if Kevala Kumbhaka is true breath retention or very subtle breathing must remain unanswered. Reliable physiological data on the effects of breath retention is not available.
Brian Cooper, PhD
Brian enjoys unmasking the myths and new-age pseudo-science currently plaguing the yoga scene. The reality is often far more interesting than the fantasy.
This article has been taken from the 2nd issue of Amrita Yoga Magazine released in 2016. If you are interested in buying this magazine, you can do so from here!