Autonomic control of the heart during circular breathing.

The analysis of heart rate variability (HRV) has become an increasingly popular method for probing the autonomic nervous system (ANS). A number of specific periodicities have been identified in the spectra of cardiac time series. One major mechanism involved in a number of these periodicities is respiratory modulation of neural traffic to the heart. One respiratory maneuver that has never been investigated is circular breathing. This technique is employed by wind musicians to produce an uninterrupted stream of sound without pauses for breathing. The current study examined the effects of circular breathing on ANS control of the heart in a highly proficient professional musician. Results indicated that circular breathing both with and without producing a sound was associated with altered autonomic control of the heart. Specifically, circular breathing was associated with increases in heart rate and decreases in high frequency HRV. This high frequency HRV has been most closely linked with respiratory sinus arrhythmia and respiratory modulation of vagal neural traffic. We conclude that the examination of novel breathing maneuvers may help to illuminate the role of respiratory modulation of HRV.