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Courtney-Cohen Claims Regarding Breath Holding Time, CO2 and the Buteyko Method

It is not the first time, when someone asked about the study by Rosalba Courtney and Marc Cohen  “Investigating the Claims of Konstantin Buteyko, M.D., Ph.D.: The Relationship of Breath Holding Time to End Tidal CO2 and Other Proposed Measures of Dysfunctional Breathing” (Journal of Alternative & Complementary Medicine; March 2008, Vol. 14 Issue 2, p. 115) since this study found the opposite result: people with higher BHT (breath holding time, or the Buteyko CP test) had lower end-tidal CO2. This topic was discussed in 2008 on the BPSN forum for Buteyko practitioners (see extracts from one of my posts below).

Buteyko teachers know and are often able to evaluate the CP of their students and other people just by watching how they breathe. Those who have heavier breathing have smaller CP numbers. Therefore, let us look what was investigated in this study and how.

Origins of the BHT - CP formula

Everybody who studied Buteyko works would suggest that the linear relationship between the alveolar CO2 and CP, which was patented by Buteyko in 1986, follows from the Buteyko Table of Health Zones. Here is this Health Table.

Buteyko Table of Health Zones (average parameters at rest)

Type of
Degree Pulse,
CO2 in
alveoli, %
AP, s CP, s MP, s
Super-health Shallow 5 48 3 7.5 16 180 210
4 50 4 7.4 12 150 190
3 52 5 7.3 9 120 170
2 55 6 7.1 7 100 150
1 57 7 6.8 5 80 120
Normal Normal - 60 8 6.5 4 60 90
Disease Deep -1 65 10 6.0 3 50 75
-2 70 12 5.5 2 40 60
-3 75 15 5.0 - 30 50
-4 80 20 4.5 - 20 40
-5 90 26 4.0 - 10 20
-6 100 30 3.5 - 5 10

How did Dr. Buteyko receive this Table? Mainly, by measuring data of his patients who learned his breathing technique in the 1960s. Who were these patients and what do they achieve? He worked mostly with severely sick and hospitalized patients. Typical CP numbers of such people are less than 10 seconds. These patients were taught by Dr. Buteyko and other Buteyko breathing doctors to get up to 60 s and more. Among these people, some got even higher numbers: up to 2-3 min for the CP test.

Dr. Buteyko recorded their parameters during this process of breathing retraining and then he discovered the linear links between all these parameters present in the Table. If we look at the Table then we can see that the level of alveolar carbon dioxide is then detected in accordance with the formula:
where P is the percentage of CO2 in the alveolar air; P0 is the 3.5 minimum percentage of CO2 in the alveolar air; K=0.05 is the dependency ratio between the level of CO2 and the breath-holding time; and T is the CP result. This link works between 5 and 60 s CP.

The range of alveolar CO2 values in this Table is from 3.5% up to 6.5% CO2. The absolute difference for this range is 86%.

If we look at the Courtney & Cohen study, their normal range is 36-42 mm Hg or 4.74% - 5.53%. The absolute difference for this range is less than 17%. Therefore, by CO2 values, the Courtney & Cohen study focused on less than a fifth (20%) of the Buteyko Table range. (The Table even goes to larger CP and CO2 numbers, but these numbers are not covered by the linear link.)

If we consider the CP range, the linear CO2-CP link works from 5 to 60 s CP, while study’s subjects had between 20 and 30 s CP. The maximum CP for the Table is 12 times greater than the minimum number, while in the Courtney & Cohen study, it is only 1.5 times larger.

1. Therefore, this Courtney & Cohen study focuses only on less than a fifth (a narrow range in comparison to the CP-CO2 range in Buteyko studies) what it claims to investigate.

Is there a link between the CP and CO2 within 20-30 s CP range?

Experience with my students suggests that even within one zone of the Table (20-30 s CP), there still a positive link between the CP and CO2. When a student with 20 s previous CP comes to the class and now has about 30 s CP, breathing of such student is different. This is exactly the range where people make a transition from chest to diaphragmatic breathing for their automatic patterns.

What is going to take place with their end-tidal CO2 during this transition? This transition makes one trick that was described on the webpage of that is devoted to capnography. End tidal CO2 (etCO2) capnography waveforms for diaphragmatic and chest breathing This page has the following capnography waveforms in order to explain how and why those people who can breathe 2 times the norm (for minute ventilation) can have nearly normal (40 mm Hg) etCO2 values. You can see these graphs on the right side.

For more details, you can visit this page (capnography) and study this trick related to end-tidal CO2. This was one of the reasons why the Buteyko patent with linear CP-CO2 link and the Buteyko Table of Health Zones, both focus only on alveolar CO2. The word "end-tidal" cannot be found in any of the Buteyko patents or in his Health Table.

2. The Courtney & Cohen study did not study alveolar CO2. They used a substitute: end-tidal CO2.

How was Dr. Buteyko getting alveolar Co2 numbers? He measured arterial O2 and CO2 values. Arterial O2 is going to tell us about a possible ventilation-perfusion mismatch, while arterial CO2 (in case of no mismatch) provides the same number as the alveolar CO2.

Therefore, when people have chest breathing, they get abnormally high etCO2 numbers. We can see this fact even in the Courtney & Cohen study. Here are extracts from this study:

  Normal spirometry (n=54) Abnormal spirometry (n=29)
Av ETCO2 (mmHg) 37(+- 4) 39(+- 4)
Av BHT-DD (s) 28(+-12 ) 20(+-8 )

We see that people with "normal" spirometry (this sounds very scientific, but probably means diaphragmatic breathing) have higher CPs and lower etCO2 than people with "abnormal" spirometry (which probably relates to chest breathing).

3. The Courtney & Cohen study got abnormal results only because of the trick that relates to end-tidal CO2 (not alveolar CO2) in the narrow zone of the transition from chest to diaphragmatic breathing.

It seems that this study substituted parameters (to study a different parameter: end-tidal CO2, not alveolar CO2), then selected a narrow range (20-30 s CP), which is less than 1/5 of the formula range and which is knowingly erroneous (unrepresentative) in relation to alveolar CO2 (the parameter studied by Dr. Buteyko).

This is how the study described their finding, "The statical significance of the negative correlation between BHT and ETCO2 which is opposite to the positive correlation claimed by Buteyko, was dependant on two extreme cases who had both previously undertaken breathing training, one using yoga and the other using the BBT [Buteyko breathing technique]."

These 2 people likely had diaphragmatic breathing (that gives lower etCO2), and this explains how the study got the negative link.

Why to bother with CP 20-30 people?

Many people learn the Buteyko method from Western Buteyko teachers by increasing their CPs from about 15 to about 25 s. This is a good achievement. It often allows to dramatically reduce or even to eliminate many types of medication. But this is not the whole Buteyko method. It is about 1/4 of the method in relation to the Buteyko norm (CP 60), and much less than that in the physiological and spiritual sense.

In order to see that some people do teach the real Buteyko method, we can look at the CO2 range in the cancer study conducted by Dr. Sergey Paschenko (Dr. Buteyko's pupil) in 2001. Dr. Paschenko reduced mortality for metastatic cancer by nearly 6 times. This study measured CO2 in the exhaled air. In my view, it was not end-tidal CO2. The average initial CO2 values were about 2.4-2.5% (in both groups). In 3 years, after breathing retraining, the controlled group of about 60 people had about 5.5% CO2 (more than double for CO2). This CO2 increase is larger than to increase the CP from about 5 to 60 seconds. This seems like the real Buteyko method.

Experience of my breathing students with CP, CO2, and Buteyko claims

Each of my students with morning CP 60+ had and has 4-5 hours of natural sleep (without any sleep restrictions), a craving/joy of physical exercise, an ability to exercise at maximum intensity with nose breathing only (mouth breathing during exercise does not provide any benefits or advantages at this health state), naturaly desire to eat raw food, natural aversion to coffee, chocolate, and many other effects.

When my new students start their course, I can see their heavy breathing, and, in most cases, it is possible to predict their breath holding times or CPs (e.g., 10, 15, or 20 s) using visual observations. Soviet Buteyko doctors also described this effects saying that it was a contest suggested to them by Dr. Buteyko: define the CP of your next patient visually. After these visual observations and carrying out the CP test, the typical lifestyle parameters of these heavy breathers are consistent: poor physical fitness, long sleep (usually about 7-9 hours), addictions, etc.

Real reasons behind such claims

Why is there this persistent trend, for some Buteyko teachers, for many years to invent various justifications related to attempts to make the Buteyko Table of Health Zones invalid, wrong, absurd, etc. and to claim that the CP does not reflects health? This is because they never experienced morning CP 60 themselves. At the same time, the patented Buteyko Table of Health Zones clearly claims that the morning CP 60, according to Dr. Buteyko, is the golden standard of human health.

These are commonly the same Buteyko teachers who ignore, in their personal lifestyle and teaching of their students, Buteyko teaching and statements that "3-4 hours of physical exercise should be the norm for a healthy person", that reduced breathing should be practiced for 2+ hours per day, and that taking cold shower and use of hard beds are also crucial parts of the Buteyko method. So, these Buteyko teachers teach only some elements of the Buteyko method (usually those elements that they like or those things that are agreeable with their lifestyle) and then the same Buteyko teachers get unhappy about the results of effects of the Buteyko method. What is has to do with science?

Extracts from my message for the BPSN (Buteyko Practitioners Support Network):
Date: Mon, 28 Apr 2008

Dr. James Oliver (GP from the UK) asked me:
> I think what might be really useful at this point would be if you could describe for us precisely how Professor Buteyko measured alveolar CO2 levels in his subjects in order to prove the relationship with CP. That would at least give us something to compare Rosalba's method against.

I replied:
In 1960s he [Dr. Buteyko, in his published studies] measured arterial O2 and CO2. O2 values provide info about no mismatch (alveolar and arterial gas values are similar), while arterial CO2 gives alveolar CO2. He invented and used some other devices using mask and gas analysis of the expired air and drawing pneumographs in real time.
The people you [Rosalba] studied fit in one sub-zone (20-30 s), whereas if you take any Buteyko table [of health zones - there are several slightly different versions of this table], you find 12 zones of health (CP – CO2 – pulse- breathing frequency - etc.) from 0 up to 180 s CP.
It seems me irrelevant from physiological, historical, medical and scientific viewpoint, how many people are in this zone now. 99% people can have 20- 30 s CP. So what? Do you study science and health or you get statistic about parameters of some modern people? If 20-30 s CP people are investigated, it can generate one point in the CP-CO2 universe. But the Buteyko method is not about digging the bog (I mean studying physiology of “normal” volunteers). It is rather about providing the standard of ideal health (CP 60 and over 48 mm Hg CO2) and showing the way there.

- " Investigating the Claims of Konstantin Buteyko, M.D., Ph.D.: The Relationship of Breath Holding Time to End Tidal CO2 and Other Proposed Measures of Dysfunctional Breathing."
- Courtney R, Cohen M (2008). Investigating the claims of Konstantin Buteyko M.D., PhD: The relationship of Breath Holding Time to end tidal CO2 and other measures of dysfunctional breathing. Journal of Alternative and Complementary Medicine, 14(2),115-123.
- Russian and Soviet patents related to the Buteyko breathing method

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