Cardiac Autonomic Control during Alternate Nostril Breathing in Subjects Novice to Yoga Practice

Objectives: To examine heart rate variability during alternate nostril breathing (ANB) in a group of individuals novice to yoga practice and to compare the effects of ANB to that of paced breathing (PB) at the same respiratory rate. Design: The study involved randomized repeated measures of two different breathing patterns. Participants: Twenty healthy individuals (22.3 ± 2.9 years) participated. Intervention: Subjects were asked to rest for 5 minutes (PRE-ANB and PRE-PB) before they participated in two different breathing exercises (ANB and PB) in a random order for 30 min. Outcome Measures: Heart rate (HR), mean arterial pressure (MAP) and heart rate variability (HRV) were measured during PRE-ANB, PRE-PB, ANB, and PB and compared using analysis of variance. HRV was reported as frequency and time domain parameters. Total power (TP; 0.0-0.4 Hz), low- (LF; 0.04-0.15 Hz), and high-frequency (HF; 0.15-0.40 Hz) ranges were selected and were natural log (ln) transformed. Time domain variables such as RMSSD, pNN50, and SDNN were also reported. Results: There was a main effect of breathing condition on HR and MAP (p < 0.05 for both) such that HR was higher during PRE-ANB and ANB compared to PRE-PB and PB and that MAP was greater during ANB compared to the other conditions. There were main effects of time on lnTP, lnLF, and lnHF (p < 0.001 for all) such that lnTP and lnLF were greater and lnHF was lower during ANB and PB compared to the PRE conditions. There was a breathing x time interaction on lnLF/lnHF (p <0.05) such that it was greater during PB compared to ANB and that it was greater during ANB and PB compared to PRE-ANB and PRE-PB. There was a main effect of breathing on pNN50 such as that it was lower during Pre ANB and ANB. There was also a main effect of time on SDNN such that it was higher during PB and ANB. No significant changes were noted in RMSSD measurements during any conditions. Conclusions: During both ANB and PB, there was a decrease in parasympathetic and/or increase sympathetic control of the heart. Additionally, ANB may result in less of a reduction in parasympathetic control than PB.