Inversions directly benefit the heart by increasing the volume of blood coursing through it. Studies have shown that women who practice yoga regularly are less likely to experience difficulty with the endocrine system. In particular, inverted poses listed are particularly noted for their soothing, calming effect on the mind and nervous system.
"Most women find that inversions on a regular basis help PMS or menopause," says Judith Lasater, a physical therapist, a yoga instructor and author of several books on yoga, among them being Relax and Renew
Laster says, ”My students often tell me that when they practice inversions, they don't get hot flashes. When they don't practice inversions, they do."
Lasater also says, inversions have a dramatic effect on what physiologists call hemodynamics — the flow of blood to every organ of the body. They have a particularly potent and measurable effect on the glands of the endocrine system including the pineal, pituitary, thyroid, parathyroid, adrenals, and hypothalamus. It is the endocrine system that controls the changes in hormone levels that happen during menstruation and menopause. And the benefits are not just for women, the endocrine health in men benefit as well.
What do inversions actually do in our bodies?
The human body is sensitive to the fluctuations of gravity because it consists of more than 60% 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 with inversions. In a 1992 Yoga International article on headstands 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.
There are four major systems in the body that the practice of inversions is said to positively influence: cardiovascular, lymphatic, nervous, and endocrine.
The circulatory system is comprised of the heart, the lungs, and the entire system of vessels that feed oxygen and collect carbon dioxide and other waste products from the cells. Arteries fan out in an intricate tributary system from the heart, which pumps freshly oxygenated blood from the lungs outward. Veins return blood to the heart, and unlike arteries, veins make up a low-pressure system that depends on muscular movement or gravity to move blood along. One-way valves at regular intervals prevent backwash and keep fluids moving towards the heart in a system known as "venous return."
Get Your Heart Healthy
Turning yourself upside down encourages venous return. According to Pat Layton, physiology teacher for the Iyengar Yoga Institute of San Francisco's Advanced Studies Program, "People have to do aerobics because they don't invert. You have to run really hard — get the heart pumping hard — to circulate blood down to the feet and up the back. Not that you shouldn't do aerobics, but inversions are a healthier way to get the benefits [to the circulatory system], particularly as you get older."
Layton believes that inversions also ensure healthier and more effective lung tissue. When standing or sitting upright, gravity pulls our fluids earthward, and blood "perfuses" or saturates the lower lungs more thoroughly. The lower lung tissue is thus more compressed than the upper lungs. As a result, the air we inhale moves naturally into the open alveoli of the upper lungs. Unless we take a good, deep breath, we do not raise the ratio of air to blood in the lower lungs. When we invert, blood perfuses the well-ventilated upper lobes of the lungs, thus ensuring more efficient oxygen-to-blood exchange and healthier lung tissue.
Finally, as Payne says, "Inverting gives the heart a break." The heart works doggedly to ensure that freshly oxygenated blood makes its way up to the brain and its sensory organs. When inverting, the pressure differential across the body is reversed, and blood floods the carotid arteries in the neck. It is believed that baroreceptors — mechanisms that calibrate blood flow to the brain — sense the increase in blood and slow the flow, thus reducing blood pressure and heart rate. It has not, however, been clinically established whether the practice of inversions could lower blood pressure over the long haul, and in fact, high blood pressure is typically considered a contraindication for inversions.
What Do Sump Pumps & Inversions Have in Common?
The lymphatic system is responsible for waste removal, fluid balance and immune system response. Lymph vessels arise among the capillary beds of the circulatory system, but comprise a separate system that transports stray proteins, waste materials and extra fluids, filtering the fluid back through the lymph nodes and dumping what remains into the circulatory system at the subclavian veins, under the collarbones. The lymphatic system is analogous to a sewage system — an intricate, underground network tied to every house in town — that keeps the citizens healthy.
Inversions, then, are analogous to the sump pump in the basement, propelling sewage into the pipeline. Lymph, like the blood returning to your heart via the veins, is dependent upon muscular movement and gravity to facilitate its return. Because the lymphatic system is a closed pressure system and has one-way valves that keep lymph moving towards the heart, when one turns upside down, the entire lymphatic system is stimulated, thus strengthening the immune system. Viparita Karani is the best example of this, as it is a mild inversion that one can enjoy for at least five minutes with no stress to the body when one is fatigued or ill.
Put Your Feet Up
It's interesting to note that for problems like varicose veins and edema (swelling) of the feet, when lymph is unable to maintain the appropriate fluid balance in the lower extremities, doctors often simply tell people to put their feet up.
Emmet Schmelig is a ERYT 500 yoga teacher and licensed massage therapist. He offers classes at Blue Sky Yoga every Wednesday at 6:30 and facilitates workshops and retreats. Check our classes & events page for any upcoming events or to take a class with Emmet.