Because inversions reverse the action of gravity on the body inside and out, they provide a powerful toning massage to the internal organs. This helps detoxify the organs by stimulating movement and counteracting stagnation. This internal invigoration also has a positive effect on muscles and skin tone. Turning the body upside down provides a different orientation to its relationship to the Earth and while holding the position provides an isometric experience that can increase bone density.
Inversions exercise the heart and encourage venous return. Many experts say that this is as good for the body as aerobic exercise for promoting a healthy heart and good circulation. Normally after arteries have circulated fresh oxygenated blood to all the body parts, the veins have to rely on muscular movement to counteract gravity and return the blood to the heart . Turning upside down enables this venous return to happen effortlessly. This also helps prevent varicose veins in the legs. When the body is inverted the heart gets a rest. Usually the heart has to work hard all day and night against gravity to move oxygenated blood up to the brain and throughout the body, but when you are upside down the blood flows on its own with out the heart having to do all the work.
Turning upside down causes the entire lymphatic system to be stimulated, thus strengthening the immune system. Turning upside down also stimulates and nourishes the endocrine glands, especially the pituitary and pineal glands, which when stimulated by the pressure created in inversions release hormones that regulate cellular metabolism, bringing health, balance, clarity, vitality and optimism to the whole body/mind system.
When we turn our bodies upside down, we are literally turning our world upside down. Turning upside down allows us to experience the advantage of different attitudes and ways to perceive. Everything we know as right side up, typical and normal is pulled out from underneath us. This disorientation requires us to draw from places in our psyches that we may not have accessed much before. In order to fully experience this new angle of perception we must relax both our bodies and minds and surrender to the Divine with faith.
Through inversions we can experience a kind of regression and rebirth. Especially the experience elicited by shirshasana when our head rests on the terrestrial plane of the ground and becomes the seat of the asana, we find ourselves going head first back into the Earth, our source. The feeling can be like diving head first back into the womb. The result can be a renewal of creativity. Physically elevating our hearts above our heads has a profound psychological effect as our intuitive feeling brain, situated in the heart, takes precedence over our rational intellectual judging mind.
The major inverted asanas are shirshasana (headstand), salamba sarvangasana (shoulderstand), halasana (plough), adho mukha vrikshasana (handstand), pinchamayurasna (forearm stand) and viparita karani (legs up the wall). They should be practiced daily. If you donâ€™t have time for a 1-2 hour asana class that includes the 14 points of a Jivamukti Yoga open class, then at least practice inversionsâ€”especially shirshasana and salamba sarvangasanaâ€”remaining in each of them for at least five minutes. If you donâ€™t have time to do that, then at the very least practice adho mukha vrikshasana and try to hold it for at least 25 breaths, against the wall if necessary. The point is to not go a day without turning upside down, unless you are a menstruating woman (in which case it may be best to rest from all inversions, because turning upside down will disturb the downward movement of apana toward the Earth).
Shirshasana is called the king of the asanas and is thus considered the most important of all the asanas. Each asana affects a particular chakra, and headstand stimulates the sahasrara (crown) chakra. The karmic relationship associated with this chakra is our relationship to God. Consciousness is chemical, and shirshasana stimulates the pituitary and pineal glands in the brain to release hormonal substances that cause an expansion of consciousness, which provides us an opportunity to let go of mundane, worldly concerns and become available for Cosmic consciousness. Inversions open a doorway to the Divine.