Yogic agnisara increases blood flow in the superior mesenteric artery.

OBJECTIVES: Medieval yoga texts claim that a special exercise of the muscles of the anterior abdominal wall, called agnisara, improves digestive function. Main objective of the study was to demonstrate change in the blood flow through superior mesenteric artery (if any) after performance of agnisara. METHODS: Ultrasound examination of the linear and volumetric indicators of blood flow in the superior mesenteric artery (SMA) before and after performing the agnisara yoga exercise 100 times was carried out in 12 healthy volunteers of both sexes (8 of them women). RESULTS: A significant increase in the diameter of the SMA, peak systolic and diastolic velocities, and blood flow in the superior mesenteric artery after performing the agnisara exercise 100 times was found, which contrasts with the established data on a decrease in splanchnic blood flow in humans in response to normal physical activity. CONCLUSION: Properly performed agnisara increases blood flow to the splanchnic region, registered by the SMA, which should contribute to adequate blood supply to the gastrointestinal tract for successful performance of digestive function.

Headstand (Sirshasana) Does Not Increase the Blood Flow to the Brain.

Objectives: Most yoga practitioners believe that headstand (Sirshasana) results in increased cerebral perfusion. This, however, is not consistent with autoregulation of the cerebral blood flow. The intent of this study was to demonstrate the effect of Sirshasana on the blood flow to the brain through ultrasound examination of the internal carotid artery (ICA). Design, location, and subjects: The ICA blood flow was measured with pulsed Doppler in 20 men and women aged 10 to 59 years (median 43) while performing the headstand (Sirshasana). Seventeen subjects were studied in 2018 in Spain at the altitude of 2,000 m, whereas the other three females were studied at sea level. Results: Although the diameter of the artery under examination during the headstand remained almost unchanged, the decrease in peak flow velocities in systole and diastole caused a significant decrease in arterial blood flow to the brain, followed by return to baseline values immediately after the antiorthostatic postural effect, likely due to the expected consequences of the cerebral blood flow autoregulation of the cerebral blood supply as well as the intracranial pressure. Conclusions: Contrary to popular belief, Sirshasana does not increase blood flow to the brain through the ICA, but results in predictable reduction in cerebral blood delivery in compliance with known mechanisms of autoregulation of cerebral blood flow. Moreover, increased ICA blood flow while performing the headstand is likely to be a contraindication to this exercise.

Hemodynamic observations of tumo yoga practitioners in a Himalayan environment.

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.