Background: Few attempts have been made to evaluate the physiology of traditional Eastern health practices. The goal of this study was to evaluate the hemodynamic effects of the mysterious Buddhist practice of tumo. Tumo is a meditative practice that produces inner heat through the alleged cultivation of body energy-channels.
Methods: This study was performed by members of an international expedition to the Himalayan Mountains in the Republic of India. The study was performed in an unpopulated outdoor mountainous area at an altitude of 16,400 ft with ambient temperatures between -10 and -15(°)C. Two (2) cohorts of subjects were studied: healthy non-yogi volunteers and tumo practitioners. All of the subjects were stripped down to their underclothes and exposed to the subzero atmospheric temperatures for 5 minutes. The volunteers were then passively rewarmed while the tumo practitioners performed tumo for up to 10 minutes. Blood pressure, heart rate, and stroke volume index (SVI) and cardiac index were measured noninvasively using a NICOM™ hemodynamic monitor, while carotid blood flow and biventricular performance were determined echocardiographically at each stage of the experiment. The total peripheral resistance index (TPRI), left ventricular ejection fraction (LVEF), and tricuspid annular plane systolic excursion (TAPSE) were determined using standard formula.
Results: Fourteen (14) subjects (six volunteers and eight tumo practitioners) completed the study. There was one female subject in each group. With cold exposure, the SVI and carotid blood flow decreased while the TPRI increased significantly in both groups. In the volunteer group, these changes retuned to baseline with rewarming. Following tumo, the cardiac index (4.8±0.6 versus 4.0±0.5 l/m(2); p<0.01), carotid blood flow (445±127 versus 325±100 mL/min/m(2), p<0.01), LVEF (68±5 versus 64±7%; p<0.05) and TAPSE (2.9±0.4 versus 2.4±0.5 cm; p<0.01) were significantly higher when compared with baseline, while the TPRI was significantly lower (1786±189 versus 2173±281; p<0.01).
Conclusions: Tumo was associated with a hyperdynamic vasodilated state with increased biventricular performance. We postulate that tumo results in a massive increase in sympathetic activity with activation of brown adipose tissue and marked heat production. The increased heat production may explain the paradoxical vasodilatation in tumo practitioners exposed to subzero temperatures.