Immediate autonomic changes during right nostril breathing and left nostril breathing in regular yoga practitioners

The ancient Indian science of Yoga makes use of voluntary regulation of breathing to make respiration rhythmic and calm the mind. This practice is called pranayama. Nadisuddhi pranayama means "purification of subtle energy paths," inhalation and exhalation are through alternative nostrils for successive respiratory cycles. Surya Anuloma-Viloma pranayama means "heat generating breathing particle" when the respiratory cycle of inhalation and exhalation is completed through the right nostril exclusively. When completed through the left nostril alone, the practice is called "Chandra Anuloma-Viloma pranayama," which means a heat-dissipating or cooling liberating practice. We compared the effect of right nostril breathing (RNA) and left nostril breathing (LNB) pranayama on heart rate variability.

The study was conducted at the Department of Physiology at an institute of national importance, after obtaining necessary ethical approvals from the Institutional Ethics Committee. Twenty healthy kriya yogi volunteers (mean age: 44 years), who are regular practitioners for the last 10-20 years, were inducted into the study. RNB pranayama starts with closing the right nostril with the thumb of the left hand followed by exhalation through the right nostril and inhaling slowly through the same nostril. This forms one round of RNB pranayama. In contrast, inhalation through the left nostril and exhalation through the right nostril exclusively is called chandrabhedana pranayama (chandrabhedana means moon-piercing breath in Sanskrit) with a similar variation called Chandra Anuloma-Viloma pranayama in which inhalation, as well as exhalation, is performed through the left nostril exclusively. The recording of electrocardiogram (ECG) for heart rate variability (HRV) analysis was taken by heart rate variability (Dinamika HRV-Advanced Heart Rate Variability Test System, Moscow, Russia). The resting and during readings of heart rate variability parameters were compared and post hoc analysis was done using Bonferroni and Holm multiple comparisons for repeated measures.

Time domain parameters: Standard deviation of normal to normal RR intervals (SDNN) and root mean square of successive NN interval differences (RMSSD) were increased at a high level of statistical significance during both pranayama maneuvres. Frequency domain parameters: LF, LF/HF ratio increased significantly. Parasympathetic activity is represented by LF when the respiration rate is lower than 7 breaths per min or during taking a deep breath. Thus, when the subject is in a state of relaxation with slow and even breathing in both RNB-right nostril and Chandra-LNB, the LF values can be very high, indicating an increase in parasympathetic activity rather than an increase in sympathetic regulation.

Our study is an acute study, where changes in HRV were seen after 5 min of RNB and LNB. However, statistically, there is not much difference in the immediate effects of the two pranayamas on heart rate variability in regular yoga practitioners.