A Functional Near-Infrared Spectroscopy Study of High-Frequency Yoga Breathing Compared to Breath Awareness

Abstract

BACKGROUND High-frequency yoga breathing (breath rate of 2.0 Hz) has been associated with changes in oxy-hemoglobin in the prefrontal region of the brain. The present study assessed the effects of high-frequency yoga breathing (HFYB) at 1.0 Hz on frontal oxy-hemoglobin (oxy-Hb) and deoxy-hemoglobin (deoxy-Hb). MATERIAL AND METHODS Forty healthy male participants were recruited for the study. The experimental group consisted of 20 participants 23-40 years old (group mean ±S.D., 26.4±4.7 years) with at least 3 months of experience performing HFYB (group mean ±S.D., 16.3±9.8 months). The control group consisted of 20 participants ages 23-38 years (group mean age ± S.D., 27.4±4.1 years), who were seated quietly for the same duration and their average experience of yoga practice was (±S.D.) 4.3±2.7 months. Each participant in the experimental group was assessed at 2 sessions (HFYB and breath awareness [BAW]) on alternate days. Hemodynamic changes were assessed using a functional near-infrared spectroscopy sensor placed over the forehead. Data were analyzed using repeated-measures analyses of variance followed by post hoc Bonferroni adjustment. RESULTS A significant reduction was observed in oxy-Hb during and after HFYB on the left and right sides compared to values before. We also found a significant reduction in deoxy-Hb during and after the quiet sitting control session compared to pre-session values on left and right sides. CONCLUSIONS The decrease in oxy-Hb during and after HFYB suggests that there was no frontal activation during HFYB when practiced at the rate of 1.0 Hz.

Figure 1

Schematic representation of the study design. – experimental group tested on two days; HFYB – high frequency yoga breathing; BAW – breath awareness and quiet sitting control (QS) tested once; – one-minute duration between practice epochs.

Figure 2

fNIR sensor showing the position of 16 voxels, 10 detectors, and 14 light sources or emitters. – detector, which detects the light (n=10); – light source or emitter, which emits the light (n=4).