Sirasana, the headstand, otherwise known as The King of Asanas, is one of the most powerfully beneficial yoga poses for both the body and the mind. By reversing the normal effects of gravity, we take pressure off the heart, aid the circulation and rest the lower back from the weight of the body. Inverting the body also inverts the pattern of blood pressure, increasing it in the head and dropping to about 0 in the feet. Our normal blood pressure is 120/80 mm Hg (that’s mercury in case you were wondering) but varies in different parts of the body. It increases below the heart and decreases above the heart, so inverting the body reverses this.
The heart pumps in two types of unidirectional circuits – pulmonary and systemic. The pulmonary circuit takes blood from the right ventricle of the heart to the lungs and back to the left atrium, picking up oxygen and releasing CO2. The systemic circuit takes blood from the left ventricle to the body, and back to the right atrium. The blood then picks up CO2 from body tissues, and releases oxygen. Both of these circuits are affected by inversions.
However, as is often interpreted, just turning upside down does not mean that there is an increase of flow of blood or oxygen to the brain. Our physical mechanisms are far too efficient – the same amount of blood is delivered to all regions of our bodies regardless of gravitational orientation.
Inversions also have an effect on venus return– (the amount of blood brought to the heart per minute). With decreased venus return – ie poor circulation - our ventricles pump less vigorously and therefore cardiac output decreases. In other words, not enough blood is pumped to the brain and vital organs. In an upright position, the venus return below the heart has to overcome a large amount of pressure and the muscles must be regularly contracted in order to keep the blood flowing upwards (soldiers standing to attention for long stints are told to contract the lower muscles of the body to prevent them from fainting). Inverting the body in poses such as the headstand increase the venus return from the lower body.
The headstand’s other main benefit relates to breathing – something yogis are somewhat obsessed by. With good reason! Inverting the body in a headstand encourages lovely deep abdominal breathing as thoracic breathing becomes much harder due to the muscle contractions needed in the chest in order to stay up. In turn the diaphragm is strengthened – when we are the right way up, the diaphragm fully relaxes after every exhale, but when we’re upside down that muscle needs to stay in eccentric contraction in order to keep all our other organs firmly in place. Constant contraction of muscles mean stronger muscles!
So. How do you actually perform a headstand? There are two main types – the Bregma Headstand and the Crown Headstand.
The bregma is the juncture between the coronal (left to right) and sagital (front to back) sutures. You might know this as the soft part of a newborn baby’s head – the fontanelle. This type of headstand leads to a more arched final position, however there is less of a tendency to roll over than in the crown headstand. Many teachers would say that the crown headstand is preferable as there is less strain on the neck.