Effects of slow breathing exercise on cardiovascular functions, pulmonary functions & galvanic skin resistance in healthy human volunteers - a pilot study

BACKGROUND & OBJECTIVES Regular practice of slow breathing has been shown to improve cardiovascular and respiratory functions and to decrease the effects of stress. This pilot study was planned to evaluate the short term effects of pranayama on cardiovascular functions, pulmonary functions and galvanic skin resistance (GSR) which mirrors sympathetic tone, and to evaluate the changes that appear within a short span of one week following slow breathing techniques. METHODS Eleven normal healthy volunteers were randomized into Pranayama group (n=6) and a non-Pranayama control group (n=5); the pranayama volunteers were trained in pranayama, the technique being Anuloma-Viloma pranayama with Kumbhak. All the 11 volunteers were made to sit in similar environment for two sessions of 20 min each for seven days, while the pranayama volunteers performed slow breathing under supervision, the control group relaxed without conscious control on breathing. Pulse, GSR, blood pressure (BP) and pulmonary function tests (PFT) were measured before and after the 7-day programme in all the volunteers. RESULTS While no significant changes were observed in BP and PFT, an overall reduction in pulse rate was observed in all the eleven volunteers; this reduction might have resulted from the relaxation and the environment. Statistically significant changes were observed in the Pranayama group volunteers in the GSR values during standing phases indicating that regular practice of Pranayama causes a reduction in the sympathetic tone within a period as short as 7 days. INTERPRETATION & CONCLUSIONS Beneficial effects of pranayama started appearing within a week of regular practice, and the first change appeared to be a reduction in sympathetic tone.