Key Points
Slow breathing improves baroreflex sensitivity, reduces blood pressure, and potentially reduces chemosensitivity
Slow breathing with ujjayi is not as effective as slow breathing alone in untrained practitioners
Choose an inhale-to-exhale ratio that is comfortable for you when practicing slow breathing
The Breathing Diabetic Summary
Slow breathing at around 6 breaths/min improves cardiovascular and autonomic functioning. For example, it increases baroreflex sensitivity (BRS), which measures your heart’s ability to adjust your blood pressure in response to changing conditions. Slow breathing also increases parasympathetic tone, leading to better autonomic balance. This study assessed two additional aspects of slow breathing.
First, it evaluated the added effect of “ujjayi” breathing. Ujjayi breathing involves tightening of the throat during the inhale or exhale to make an ocean sound (check out the Wiki article for a simple explanation). It can be somewhat challenging to learn, but many trained yogis use it exclusively during their yoga practice.
Second, this study examined how the ratio of inhale to exhale affected cardiovascular and autonomic outcomes. Extended exhales are regularly practiced for relaxation. For example, you perform a 4 sec inhale and 8 sec exhale. However, an equal ratio has also been proven to enhance heart rate variability (for example, 5 sec inhale, 5 sec exhale). Here, they assessed these different ratios to help establish the best approach for beginners to slow breathing.
Study Details
The study had seventeen participants. Measurements were taken in the supine position while the subjects breathed spontaneously for three minutes. Then, they performed the following breathing protocols:
Controlled breathing at 15 breaths/min
Controlled breathing at 6 breaths/min with 5 sec inhale and exhale
Controlled breathing at 6 breaths/min with 3 sec inhale and 7 sec exhale
Both 6 breaths/min protocols, but with ujjayi.
The order of the slow breathing was selected randomly for each subject, and there was a two-minute break between each protocol.
Slow Breathing without Ujjayi is More Effective for BRS
The results showed that all of the slow breathing techniques improved BRS. However, there was no added benefit of ujjayi and it actually worsened BRS slightly when compared to slow breathing alone.
Slow Breathing Reduces Blood Pressure
Interestingly, slow breathing increased heart rate, except when practiced with an equal inhale/exhale. However, slow breathing reduced diastolic and systolic blood pressures. The decrease was most significant when an equivalent inhale/exhale was used. Again, slow breathing alone outperformed ujjayi.
Slow Breathing & Chemosensitivity
Lastly, they found that slow breathing decreased chemosensitivity. However, the measurement of chemosensitivity was heuristic: it was defined as the tidal volume divided by inhale time. That is, if your tidal volume increased for a given inhale time, that would indicate an increased chemosensitivity (because you are taking a bigger breath over the same inhale time).
Conversely, they also measured end-tidal CO2, and these results showed that all versions of slow breathing significantly reduced CO2 compared to spontaneous breathing. People often overcompensate for the slow breathing rate with bigger breaths, which appears to have happened here. Consistent training or biofeedback can reduce this over-breathing.
In any case, although they concluded that slow breathing reduced chemosensitivity, the significantly decreased end-tidal CO2 does not support this finding in my opinion.
Breathe at a Ratio that is Comfortable to You
To summarize, this study found that slow breathing increased BRS and reduced blood pressure. It also reduced their measure of chemosensitivity. Although using an equal inhale to exhale ratio showed slightly better results, they suggest that “practitioners can engage in a ratio that is personally comfortable and achieve the same BRS benefit.”
Interestingly, ujjayi worsened the results when compared to slow breathing alone. They hypothesize that the extra effort needed for ujjayi dampened the parasympathetic response. These results would likely be different in seasoned ujjayi practitioners.
Therefore, we can conclude that slow breathing at a rate of 6 breaths/min improves cardiovascular and autonomic function. The best way to begin is to choose a ratio that is comfortable for you.
Abstract
Slow breathing increases cardiac-vagal baroreflex sensitivity (BRS), improves oxygen saturation, lowers blood pressure, and reduces anxiety. Within the yoga tradition slow breathing is often paired with a contraction of the glottis muscles. This resistance breath "ujjayi" is performed at various rates and ratios of inspiration/expiration. To test whether ujjayi had additional positive effects to slow breathing, we compared BRS and ventilatory control under different breathing patterns (equal/unequal inspiration/expiration at 6 breath/min, with/without ujjayi), in 17 yoga-naive young healthy participants. BRS increased with slow breathing techniques with or without expiratory ujjayi (P < 0.05 or higher) except with inspiratory + expiratory ujjayi. The maximal increase in BRS and decrease in blood pressure were found in slow breathing with equal inspiration and expiration. This corresponded with a significant improvement in oxygen saturation without increase in heart rate and ventilation. Ujjayi showed similar increase in oxygen saturation but slightly lesser improvement in baroreflex sensitivity with no change in blood pressure. The slow breathing with equal inspiration and expiration seems the best technique for improving baroreflex sensitivity in yoga-naive subjects. The effects of ujjayi seems dependent on increased intrathoracic pressure that requires greater effort than normal slow breathing.
Journal Reference:
Mason H, Vandoni M, Debarbieri G, Codrons E, Ugargol V, Bernardi L. Cardiovascular and Respiratory Effect of Yogic Slow Breathing in the Yoga Beginner: What is the Best Approach? Evid Based Complement Alternat Med. 2013;2013:743504. doi: 10.1155/2013/743504.