To Breathe or Not to Breathe!

Breathing less than normal can calm the nervous system, decrease appetite and cause more oxygen to be transported to the brain. Breathing more than normal can have some beneficial effects too, however it also can make you feel dizzy, jittery and hungry. It is also better to keep breathing exercises and physical exercises separate until one is firmly established in the physical exercises. Once one no longer needs to focus on alignment and can confidently and safely perform the postures, doing simple or more complex breathing exercises can further deepen the physical practice.


Capnometer Study by Simon Borg-Olivier: Hypoventilation increases CO2 levels in your breath and Hyperventilation decreases CO2

Capnometer Study by Simon Borg-Olivier: Hypoventilation increases CO2 levels in your breath and Hyperventilation decreases CO2


The western yogic world is divided in opinion in many areas, one of which is “how to breathe”. Questions such as the following are often raised:

Should we separate breathing practice (pranayama) from physical practice (asana)?

Is it more beneficial to breathe more than normal or less than normal?

As with many things in life, there is no totally right or wrong answer.  No way of breathing is in itself good or bad.  It is matter of ‘how’ and ‘when’ to breathe in each way.

The facts that we know about breathing are quite compelling.

Medical science has shown for more than a century that the more you breathe (hyperventilate), the less blood goes to the brain and the heart, and the less oxygen can get absorbed in the lungs. Any fit person knows that their fitness reflected in how little they breathe (or pant) after they do exercise. It is then no surprise that the ancient yogic texts state too that the art of pranayama is the art of learning how to breathe less than normal.
When you breathe less than normal (hypoventilate) you begin to accumulate more carbon dioxide. Every physiology textbook explains that carbon dioxide is a very powerful and important substance in the body. Carbon dioxide causes the expansion of the blood vessels to the brain and heart (vasodilation) improving blood flow. It opens the bronchial tubes in the lungs (bronchodilitation), thus improving breathing. It calms the nervous system reducing stress and many other nervous conditions. Carbon dioxide is also the main reason for the Bohr effect, which causes more oxygen to be deposited in your body cells. When oxygen is used in your cells in the metabolism of sugar, you get 19 times as much energy as compared to when you metabolise sugar in the absence of oxygen.

The Bohr effect is a physiological phenomenon, known for more than 100 years, that says that a decrease in blood pH (more acidity, less alkalinity) or an increase in blood CO2 concentration will result in haemoglobin proteins (in red blood cells) releasing their loads of oxygen, and a decrease in carbon dioxide or increase in pH (less acidity, more alkalinity) will result in hemoglobin picking up more oxygen and not allowing it to enter body cells. Since carbon dioxide reacts with water to form carbonic acid, an increase in CO2 results in a decrease in blood pH.

Measuring CO2-levels using an expiratory capnometer

A capnometer is a medical device for measuring the carbon dioxide levels in the body. An expiratory capnometer is a non-invasive device that measures the concentrations carbon dioxide (CO2) during the exhalation. The graph below clearly shows the effect a personal experiment where I did  two four-minute-breathing exercises (pranayamas) and measured my  levels of carbon dioxide in the exhaled breath using an expiratory capnometer. Note that in the results below, with this device you can only measure CO2 when you are exhaling. Note also that CO2 mostly becomes carbonic acid in the body.


Increased levels of CO2 and carbonic acid in the body (up to a point) tend to promote the following effects:
* increased transfer of oxygen via the lungs to the blood (bronchodilitation)
* increased blood flow to the brain and heart (vasodilation)
* increased transfer of oxygen from haemoglobin in the body cells (Bohr effect)
* increased calmness of the nervous system (pH effect on nerves)
* decreased hunger (pH effect on desire for acidic foods)

EXPERIMENT 1: BREATHING EXERCISE 1: 4 x one-minute breaths with 30 seconds inhalation followed by 30 seconds exhalation:

1. Start normal breathing 1 minute (m) [CO2=33] 2. Start 30 seconds (s) inhale then 30s exhale (x 4 breaths) [CO2=46] 3. Resume normal breathing 2m [CO2=36]

RESULTS OF EXPERIMENT 1: The results of this first breathing exercise (Experiment 1) are that CO2 levels increased significantly during the slow breathing and remained higher than at the starting level after natural breathing was resumed. This implies that pH decreased due to the increased levels of carbonic acid both during and after the experiment. As to be expected based on the reported effects of increased levels of CO2 and carbonic acid (see above), subjectively following the experiment I felt very warm, clear in and focused in my head, very relaxed and definitely not hungry.

EXPERIMENT 2: BREATHING EXERCISE 2: 40 short deep abdominal breath, followed by 60 seconds exhalation retention followed but 110 seconds inhalation retention followed by 10 seconds exhalation, then normal breathing:

3. Normal breathing after first exercise 2m [CO2=36] 4. Start 1m rapid breathing (40 breaths/m) [CO2=17] 5. Start 60s hold breath out fully, then 80 hold breath in fully
6. Start 10s exhalation [CO2=48] 7. Resume normal breathing [CO2=37]

RESULTS OF EXPERIMENT 2: In the second breathing exercise (Experiment 2) I did a period of hyperventilation followed by a period of hypoventilation (often called Bhastrika in many yoga traditions). During the period of hyperventilation (about 20 deep, full and quite fast breaths per minute) my CO2 levels fell very sharply to the lowest level in both experiments. My body became cold and tingly. I also became somewhat dizzy. These are typical symptoms of hyperventilation. After the period of hyperventilation I did one 3 minute breath which included nauli kriya (abdominal ‘churning’ using the rectus abdominis and the oblique abdominal muscles) during an exhalation retention of one minute. Holding my breathe out this long seemed very easy since I was not getting the usually present signal to breathe from high levels of CO2 since I had ‘blown off’ my usual CO2 levels in the period of hyperventilation. I subsequently took an inhalation of 30 second, followed by inhalation retentions with bandhas (opposing muscle co-activation around the trunk) for a seemingly easily held period of about 110 seconds, followed by a 10 second exhalation. During that final exhalation my CO2 levels increased to their highest level in both breathing exercises and remained higher than at the starting level after natural breathing was resumed. Therefore it is safe to conclude that my blood and intracellular pH decreased (became more acidic) due to the increased levels of carbonic acid both during and after the experiment. As to be expected based on the reported effects of increased levels of CO2 and carbonic acid (see above), subjectively following the experiment I felt even warmer, very clear and focused in my mind, very relaxed yet energised and completely satiated with no desire to eat for some time after.

In terms of diet, it is interesting to note that with regular practice of this sort myself and others report much less desire for acidic foods (such as high protein foods, grains, animal products, processed foods etc.) in general and seem to be more easily satiated by simpler more alkaline foods such as fruits, salads and vegetables.

It is important to note that the graph alone does not show that blood flow to the brain increases with hypoventilation. It only shows that the two hypoventilation exercises I did increased CO2 levels both during and after the exercise. My experiment also showed that when I did a hyperventilation exercise it decreased CO2 levels. However, in the graphic below, based on an MRI study by Dr Peter Litchfield (see a carbonic acid induced vasodilation (expansion) of the arteries to the brain and the Bohr-effect has been shown to take place in most situations when there is an increase in CO2 and carbonic acid. From this graphic you can see that during normal breathing there is adequate blood flow and oxygenation of the brain, but after on a short period (one minute) of hyperventilation the blood flow and oxygenation of the brain is significantly reduced.

For those interested here is link to a nice page that gives some simple explanations of the effect of CO2 on vasodilation and the Bohr-effect, with some published references, that can help to give the link, and provide the evidence, that I didn’t specifically give in this post, that an increase in CO2 levels can lead to increase oxygen levels in the brain and a general increase in health throughout the body.

Breathing more than normal can be good too

Controlled hyperventilation can have its benefits too, if balanced with a reduction of breathing for a period of time following.  I do about three to five rounds of the following breathing exercise on a daily basis: one minute hyperventilation, followed by one breath for 3 minutes, then finish with about 20 minutes of meditation with minimal breathing. I also know powerful yogis in India who hyperventilate during an entire hour of physical exercise but then sit in meditation for several hours after with hypoventilation to balance the effects on the their bodies.

I only mention this because in my travels I see so many of the people in the yoga and in the exercise world today practicing hyperventilation throughout their entire practice yet they don’t balance it afterwards. Often it is mistakenly thought that slow deep breathing is just 3 seconds in and 3 seconds out, for a full lung of air whilst not doing too much physical activity. This would mean breathing about 50 litres of air per minute (10 X normal). Often these people report they are finishing their yoga practice feeling spaced out, dizzy, exhausted and hungry. This is often how yoga practitioners think they are supposed to be feeling and that the spaced out feeling is the essence of yoga, whereas of course it is much better (and healthier I think ) to generally finish your exercise and/or yoga feeling clear, focused, calm energised and not desperate for food.

Keep it simple until you are established in your asana practice

However, nothing is ever completely right or wrong and definitely depends on individual needs. For example, my 6-year-old son, often does not have an appetite, so I sometimes encourage him to hyperventilate (with breathing games such as ‘from how far can you blow out this candle’) and after that practice he is suddenly hungry again!

It is also better to practice breathing exercises and the physical exercise (posture and movement) separately until one is firmly established in the physical exercise you are doing. Once you no longer need to focus on alignment and can make sure you are not damaging your body, you can begin doing simple and then more complex breathing exercises during your physical exercise. However, when learning a new physical exercise the best way to breathe is with your own natural breathing.

Breathing exercises can also be of benefit to you

It is also important to note that it is  good to exercise the muscles of breathing too, and point that although arguably the main purpose of breathing is to bring more oxygen to the cells, there are many other reasons we breathe and many things we can do with our breathing. These subjects will be discussed in further blogs and videos, but have already been mentioned in previous blogs including this one.

If you want to learn more of this you can join one or our online courses – the ‘Anatomy and Physiology of Yoga’ and the ‘Essentials for Teacher Training: Yoga Fundamentals’ by going to These courses are the public versions of the award-winning RMIT university courses that were written by me and fellow physiotherapist and co-director of Yoga Synergy, Bianca Machliss. They are the culmination of the 30 years of teaching experience.

Thanks to Breath Therapist Roger Price for assistance with the capnometer


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