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The cardiovascular effects of slow breathing.

What is the best approach?




BRS is a measure of the heart's ability to effectively modify and regulate blood pressure according to the demands of a given situation.


Slow breathing increases cardiac-vagal baroreflex (BRS) sensitivity , improves oxygen saturation, lowers blood pressure, and reduces anxiety. In the yoga tradition, slow breathing is often associated with a contraction of the glottis muscles. This resistance breath is called "Ujjayi" and it is performed at different rates and inhale/exhale ratios. To test whether ujjayi had additional positive effects to slow breathing, we compared BRS and  ventilation of the palms  under different breathing patterns: equal / unequal inspiration / expiration, at 6 respiratory cycles / min, with / without ujjayi. 

The study was done on 17 healthy young participants, non-practitioners of yoga. BRS increased with slow breathing techniques with or without ujjayi exhalation (𝑃 < 0.05 or more), except during “  inspiration + expiration in ujjayi  ".
The maximum increase in BRS and decrease in blood pressure was found in slow breathing with equal inspiration and expiration.

This corresponds to an improvement in oxygen saturation without an increase in heart rate and ventilation. The Ujjayi technique demonstrated a similar increase in oxygen but slightly less improvement in baroreflex sensitivity with no change in blood pressure.
Slow breathing with equal inspiration and expiration seems to be the best technique to improve baroreflex sensitivity for inexperienced practitioners.
The effects of ujjayi appear to depend on increased intrathoracic pressure which requires greater effort than slow normal breathing.

(Ujjayi is a type of breathing best suited for practicing postures, so the conclusions of the study seem quite logical; to read more: type " Ujjayi " in the search engine  of the site)



Introduction :

Research on the respiratory process demonstrates that slow breathing (around 5-6 breaths per minute) in the average adult, can increase vagal activation leading to reduced sympathetic activity (calming), increased sensitivity cardiac-vagal baroreflex (BRS), and increased parasympathetic activation which correlates with mental and physical health.  


BRS is a measure of the heart's ability to effectively modify and regulate blood pressure according to the demands of a given situation. A high degree of BRS is therefore a good marker of heart health.


The increase in BRS due to slow breathing could be present due to increased tidal volume which stimulates the growth of Hering-Breuer reflex, an inhibitory reflex triggered by stretch receptors in the lungs that feed on the vagus . Additionally, slow breathing increases oxygen uptake that arises from greater tidal volume (𝑉𝑡), due to reduced anatomical and physiological dead space effects. This in turn produces another positive effect, ie a reduction in the need to breathe.  


Ujjayi - resistance breathing, a breathing practice taught by yogic tradition, reduces airflow, and during exhalation one increases intrathoracic pressure due to a slight contraction of the glottis muscles, resulting in vagal activity.


The increase in intrathoracic pressure during expiration should also increase oxygen uptake, potentially elevating blood pressure more than slow breathing alone and inducing greater BRS. 

Finally, breathing facilitates better control of airflow and, therefore, breathing rate.  


Therefore, Ujjayi may be a more effective method for complementary and alternative medicine than slow breathing per se. Accordingly, we tested whether ujjayi breathing would improve oxygen saturation and BRS more than slow breathing alone.





2. Materials and methods: 

Topics. The protocol for this study was approved by the Ethics Committee of the University of Pavia, Italy, and all participants gave their informed consent to participate in this study.


17 healthy young participants were recruited by word of mouth among university students and staff. Participants provided information on their general fitness level, athletic ability level (including specialties that lead to yoga-like practices such as diving and martial arts), smoking and alcohol consumption with average consumption . These characteristics and the anthropometric characteristics of the subjects are shown in Table 1.






Body weight index 

Training sessions / week

Quantity of dishes / week 


Alcohol (glasses / week) 

Diving enthusiasts, mart arts.

Features  some participants 


Before the test, participants spent about 10 minutes learning how to do ujjayi with a qualified yoga teacher. They were then connected to the measuring devices. The trial phase included 7 conditions distinguished by respiration rate and whether or not ujjayi was included.  


Although the effects described for ujjayi should normally take place during exhalation (as is normally practiced), we have also included ujjayi during both phases: inhale and exhale, as some yoga teachers suggest.  




We also decided to perform the ujjayi without the addition of "Bandhas" (i.e., contractions at the level of the perineum or the abdomen or the chin near the chest), since for the participants non-experienced, these additional movements are difficult to achieve without prior practice. This is also in agreement with many schools of yoga, which do not necessarily associate bandhas with ujjayi.  



Recordings took place in the supine position for 3 minutes with spontaneous breathing, for 2 minutes of controlled breathing at a rate similar to normal spontaneous breathing (15 breaths/minute), and for 2-minute periods of slow deep breathing at the rate of 6 cycles / minute with an equal or unequal ratio of inspiration / expiration and with or without ujjayi  


(Table 2 reports the methodology for the different recordings).

Respiratory rate 

1.  Spontaneous  

2. Fast: 15/min: (2 sec. inspiration + 2 sec. expiration)

3. Slow: 6/min: (5 sec. inspiration + 5 sec. expiration)  

4. Slow: 6/min: (5 sec. inspiration + 5 sec. expiration)  

5. Slow:  6/min  (5 sec. inspiration + 5 sec. expiration)

6. Slow:  6/min  (3  dry. inspiration + 7  dry. expiry)

7. Slow:  6/min  (3  dry. inspiration + 7  dry. expiry)

3. Results

The results are shown in Table 3 and Figure 1. 

Overall, the data was consistent and we did not find differences between male and female participants.


BRS (Figure 1). Compared to spontaneous breathing, fast breathing caused a decrease in BRS, and slow breathing (with or without ujjayi breathing) increased BRS.

This increase was observed in both symmetrical breathing (5 sec inspiration and 5 sec expiration) and asymmetrical (3 sec inspiration and 7 sec expiration) slow breathing conditions.

Ujjayi breathing had demonstrated the effect of reducing the increase in BRS during slow breathing alone, and this was further reduced with ujjayi on inspiration and expiration (which was not significantly higher than the line basic).

These differences are even more pronounced with respect to controlled breathing at 15 cycles/minute, which demonstrated highly significant differences from  spontaneous breathing, but in the opposite direction.

Oxygen saturation, carbon dioxide and ventilation:

Slow breathing and controlled breathing of 15 breaths/minute increased oxygen saturation over baseline.

When the slow breathing was done in conjunction with ujjayi, the oxygen saturation still increased slightly, but however, this was a very significant change given that the initial oxygen saturation was already high -> around 98, 3% (Table 3).  



Heart rate and blood pressure. 

Except for slow breathing with inspiration equal to exhalation time, any slow breathing reduced the RR interval (increased heart rate). Ujjayi (*while quiet, not while practicing AP_postures) increased heart rate more compared to slow breathing


RR Interval (ms)

Blood tension.  systolic

Diastolic blood pressure


Saturation  in oxygen (%)  

Carbon dioxide (mmHg)

Vt (spontaneous breathing)

Ve (spontaneous breathing) 

Table 3: Respiratory effects on cardiovascular variables

Slow breathing reduced diastolic blood pressure, especially when practiced with inspiration equal to expiration time. Ujjayi also reduced the drop in blood pressure induced by simple slow breathing (Table 3).  




4. Discussion

The present study showed that in almost all forms of yogic breathing performed by the participants there was an increase in BRS (only slow breathing with ujjayi during inspiration and expiration did not show statistically significant results). significant) and oxygen saturation, with reduced blood pressures.  


The greatest improvement was found in slow breathing without ujjayi, on the other hand controlled breathing at a rate of 15 breaths/min resulted in lower BRS. 

In all slow-breathing elms, a statistically significant effect of increased oxygen saturation compared to its initial level was found, confirming the relationship between high levels of oxygen uptake and BRS.  


However, ujjayi showed the highest saturation, but it did not correspond to the greatest improvement in BRS, probably due to the increase in respiratory effort (as

increased heart rate).  


These results show that simple slow breathing with the inspiration equal to the expiration is the best compromise to obtain positive cardio-respiratory effects in the yoga practices of non-experienced people.  





5. Conclusions

Based on our results, slow breathing with similar inspiration and expiration times is the most effective and best way to increase BRS and improve oxygenation. Ujjayi  demonstrated additional limited benefit on slow breathing done at 6 breaths/min; however, the effects may be more pronounced in the case of hypoxia, and this may be the subject of future investigations.  


As we did not find a significant difference between symmetrical and asymmetrical breathing, it is suggested that practitioners can use the ratio in which they are personally comfortable and they can expect the same effect at the level of BRS.  


These results could be useful in choosing the optimal strategy to train patients undergoing rehabilitation based on yoga practices. As previous studies have shown, patients suffering from different pathologies (such as heart disorders, hypertension) can benefit from the practice of this slow breathing, while no contraindications have been reported to date. .



















source article (english):



HeatherMason,1 Matteo Vandoni,2 Giacomo deBarbieri,3 Erwan Codrons,2

Veena Ugargol,4 and Luciano Bernardi2,3

1 Department of Neuroscience, Roehampton University, London, UK

2Department of Public Health and Neuroscience, University of Pavia, Pavia, Italy

3Department of Internal Medicine, University of Pavia and IRCCS San Matteo, Pavia, Italy

4Department of Psychology, The Open University, London, UK

Correspondence should be addressed to Luciano Bernardi;

Received 18 December 2012; Accepted March 22, 2013

Academic Editor: Elisa Harumi Kozasa



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