The opening part of this extended look at a 2018 review of yogic breathing (YB) examined some neurocognitive effects of pranayama, and how focused nostril breathing can trigger calmness.
Does breathing fast or slow also affect the body’s psychophysiological reaction? The authors cite a number of studies suggesting that most yogic breathing leads to a parasympathetic – relaxing – shift, apart from high-frequency kapalabhati.
Groups training in slow pranayama for three months showed increased parasympathetic activity and decreased sympathetic (fight or flight) activity, while those in a fast-breathing group showed no change.
That’s not to say fast pranayama has no effects – another study, on 90 young healthcare students, showed reduced levels of stress in slow and fast groups, but only the slow group also had significantly reduced cardio variables.
A nifty study examined the role of parasympathetic activity by giving one group practising five minutes of slow bhastrika a drug blocking such activity and seeing how their cardio results compared with an undosed group. Those who took the medication showed no significant changes in blood pressure or heart rate, while these readings decreased in the other group.
In other words, enhanced parasympathetic activity seems crucial to modulating the autonomic nervous system.
A 2017 study examined the effects of yogic breathing on teenage swimmers who averaged about 10 kilometres in the pool each day.
The 27 subjects were divided into YB and control groups, with the YB group assigned 10 minutes each of sectional breathing (Vibhagiya pranayama), yogic bellows breathing (bhastrika), and alternate nostril breathing (nadi shodhana) with breath retention (anthar kumbhaka), five days a week, for one month.
The thinking behind setting those particular exercises was as follows: nadi shodhana is effective in increasing lung capacity, and when twinned with bhastrika also raises the volume of air that can be shifted in a set time period. Adding in the breath retention raises the availability of oxygen to the tissues, while sectional breathing increases the efficiency of muscles in the diaphragm and abdomen.
Together, they “are expected to alleviate sport anxiety through reduction of sympathetic arousal, enhance endurance of the respiratory muscles and vital capacity of the lungs thereby reducing fatigue and acute respiratory symptoms”.
The below shows the body positions the YB group were told to adopt before the sectional breathing exercise, which ran as follows:
Abdominal breathing: Instructions were given to inhale by bulging out the abdominal muscles and exhale by drawing back the abdomen inward.
Thoracic breathing: Instructions were given to inhale by expanding the chest muscles and exhale by returning the chest to its normal position. This was repeated for 10 rounds.
Upper lobar breathing: Instructions were given to inhale raising the collar bones and shoulders upwards and backwards and exhale by dropping the shoulders into a resting position. This was repeated for 10 rounds
Swimmers had a number of stats measured on day 1 and day 30. After the month was up, the YB group’s number of strokes per breath had risen from approx. 2 to 3.5, while the control group’s stayed at about 3. The YB group also showed “significant” change in lung capacity and the amount of air that passed through the lungs..
An unlinked study speculated that the effects of yogic breathing might be due to arterial blood oxygenation, although that turned out not to be the case. But another study observed that right-nostril breathing – sympathetic-triggering – increased oxygen consumption and thus the metabolic rate, compared with left- and alternate-nostril breathing. Those thinking this might be a short cut to losing weight should however note it also increases blood pressure.
And the final study for the week examined the presence of biomarkers in saliva. One, charmingly named Deleted in Malignant Brain Tumor-1 (DMBT-1), was elevated as much as 11 times that of a control group’s levels 15 minutes after a session of YB. This link from last month suggests that DMBT-1 may “play a role in the interaction of tumor cells and the immune system”.
Next week: more health benefits of yogic breath