Abstract
Background: Various types of breathing exercises have various effects on autonomic nervous system like fast breathing increases sympathetic tone and slow breathing increases parasympathetic tone. But these changes are seen when those exercises are done for long duration. Heart rate variability (HRV) reveals the autonomic status very effectively. So took up the study to know the effects of short duration (5 min) of slow deep breathing on heart rate variability.

Aims & Objective: To study the HRV Before and after five minutes of slow deep breathing in healthy adults.

Materials and Methods: 20 healthy adults aged between 30 to 40 years and not practicing any kind of breathing exercises or yoga were involved in the study. Using powerlab, AD Instrument polyrite, HRV was calculated by recording ECG in Lead II for five minutes. Then the participants were made to slow deep breathe for 5 minutes, again HRV was calculated. The time domain parameters of HRV studied were Standard deviation of all normal-to-normal intervals in milliseconds (SDNN) and Root Mean Square Successive Difference in milliseconds (RMSSD). The frequency domain parameters studied were low frequency in normalized units (LF nu), high frequency in normalized units (HFnu) and the ratio of LF to HF (LF/HF ratio). Data was analysed by paired t test.

Results: Heart rate did not show much of variation. There was significant increase in LFnu (46.91±14.51, 60.79±17.29 and p 0.009), decrease in HFnu (43.56±17.59, 30.17±13.52 and p 0.002), increase in LF/HF ratio (1.43±0.84, 3.06±3.22 and p 0.03). SDNN and RMSSD did not show significant change.

Conclusion: Effect of slow deep breathing for a short duration of five minutes in healthy adults who are not practicing any kind of breathing exercise or yoga is shift of the cardiac sympathovagal balance towards the sympathetic predominance.

Key words: Slow Deep Breathing; Heart Rate Variability (HRV); Short Term Effect