Abstract
Background: Slow and deep breathing leads to an immediate decrease in blood pressure and increase in heart rate variability (HRV). Maximum HRV is reported during breathing at 0.1 Hz frequency (6 breaths/minute). In hypertensive patients, slow breathing at 0.1 Hz frequency has been shown to improve the arterial baroreflex sensitivity (BRS) and decrease the blood pressure.

Aims & Objective: This study was designed to see whether regular practice of slow breathing exercises will bring about changes in the HRV and blood pressure even during natural breathing in healthy participants.

Materials and Methods: Eight healthy participants performed slow breathing exercises at 6 breaths per minute, for 30 minutes daily for 4 weeks. Their respiratory rates, mean heart rate, standard deviation of the normal-to-normal RR intervals (SDNN) and mean arterial pressure (MAP) were compared before and after the 4 weeks of breathing exercise.

Results: The resting MAP decreased significantly from 82.33 ± 3.40 to 79.17 ± 3.64 mm Hg (P < 0.05), after the 4 weeks of respiratory training. The respiratory rates of the participants also showed a significant decrease (P < 0.01). Although there was an increase in the SDNN during supine rest, it was not statistically significant. Nevertheless, the SDNN during quiet standing increased significantly from 36.63 ± 4.44 to 46.25 ± 4.20 msec (P < 0.05). Training did not significantly change the mean heart rate.

Conclusion: This study shows that deep slow breathing training reduces the spontaneous respiratory rate and MAP while increasing the HRV during quiet standing in healthy participants.

Key words: Slow Breathing Training; Blood Pressure (BP); Respiratory Rate; Heart Rate Variability (HRV)