Everybody Upside-Down

Let gravity work for you. Inversions are good for your lungs, heart, thyroid, and more.

By Yoko Yoshikawa

Defying Gravity

Until very recently, there has been little interest in the West in objectively documenting the effects of yoga on health, especially for the more advanced or esoteric practices, such as inversions. The medical doctors who have conducted the existing studies are predominantly Indian. Ralph Laforge, M.Sc., managing director at a clinic at Duke University Medical Center and an authority on the scientific foundations of hatha yoga, knows of only two clinical trials in this country designed to determine the physiological benefits of inversions, both of which were too "statistically underpowered" to draw clear conclusions.

Our understanding of how inversions benefit us, then, is built upon expert opinion, case studies, and educated reasoning. In the absence of more scientifically rigorous studies, we can cite biomechanical principles, measure indices such as heart rate or blood pressure, and witness the effects of inversions on people who practice regularly.

All the evidence points to one principal, galvanizing effect that inversions have on the practitioner: They upend one's relationship to gravity. Gravity has a profound effect on the physiological processes of the human body. As NASA discovered and Jerome Groopman reported in a New Yorker article (February 14, 2000), once humans enter zero gravity, we are subject to severe biomedical problems. Our sense of balance, determined by the vestibular system of the inner ear and calibrated to minute fluid movements, is destroyed. Blood, no longer weighted in the lower torso and legs, floods upwards and the heart speeds up, provoking dehydration and eventually anemia. Muscles atrophy and bone mass drops precipitously.

Here on earth, gravity slowly but surely weighs us down and saps our strength. We stand, sit, or walk with head above the heart, legs and pelvis underneath. As the years rack up, so do the damages. Subcutaneous fat sags. Varicose veins and hemorrhoids erupt. Weary of incessantly pumping blood through its vast circulatory network, the heart falters. According to Payne, the ancient yogis called gravity "the silent enemy." The yogi performs a martial-arts sleight-of-hand: Upend oneself and enlist gravity's power to arrest the ravages of that self-same force.

The human body is sensitive to the fluctuations of gravity because it consists of more than 60 percent water. From the skin in, the body is dense with cells, floating in a bath of intercellular fluid. A complex network of vessels weaves in and around every cell, steadily moving fluids through valves, pumps, and porous membranes, dedicated to transporting, nourishing, washing, and cleansing.

According to David Coulter, Ph.D., who taught anatomy at the University of Minnesota for 18 years, when one inverts, tissue fluids of the lower extremities drain—far more effectively than when one is asleep. Areas of congestion clear. In a 1992 Yoga International article on Headstand and the circulatory system, Coulter wrote: "If you can remain in an inverted posture for just 3 to 5 minutes, the blood will not only drain quickly to the heart, but tissue fluids will flow more efficiently into the veins and lymph channels of the lower extremities and of the abdominal and pelvic organs, facilitating a healthier exchange of nutrients and wastes between cells and capillaries."

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