Nadi Shodhan Pranayama
The purpose of Pranayama is to purify the nerves and thereby to strengthen the nervous system. It is as easy to do as it is useful. Increase the duration gradually after attaining the concentration of mind.
Sit in any comfortable posture: Padmasana, Siddhasana or Sukhasana. Make your breathing normal. Close your right nostril with your thumb and fill in the breath through the left nostril. When the breath has been filled inside, close the left nostril with your third finger and stay in this state of Antrik Kumbhaka for a few seconds. Then lift the thumb from the right nostril and exhale slowly, keeping the left nostril closed.
Repeat the process by inhaling through the left nostril and exhaling through the right nostril. This will complete one full round of Nadi Shodhana Pranayama.
What needs to be emphasised in this process is the necessity of maintaining a ratio of rhythm in inhaling and exhaling. When you exhale after doing Antrik Kumbhaka (holding the breath in), your breath should not come out all at once in an uncontrolled way. Instead, it should be so regulated that it comes out very slowly and remains under your full control during this process. Hold your breath as long as you can conveniently do so; and when you release it, do it very slowly.
When you have enough practice of this process, set your breathing in a regular way. Suppose, you take 4 seconds in inhaling, then retain it inside for 8 seconds and release it also in 8 seconds. That is, the ratio of the three processes should be 1 : 2 : 2. After enough practice, change this ratio to 1 : 4 : 2. It means that if you now take 5 seconds in inhaling, then retain it for 20 seconds and release it in 10 seconds. You need not apply force for retaining your breath; it should be done in a natural way. There should be proper ratio between the Pooraka Kumbhaka and Rechaka Kumbhaka. While doing Rechaka, the breath should come out in such a slow measure that it is not felt at a distance of about 3 inches from the nose. Similarly in Pooraka, the inhaling should be so slow as if only air around a distance of about 3 inches is affected.
Pooraka and Rechaka are technical terms used in Pranayama. In yoga, taking in and taking out breath is called Shwasa and Prashwasa. Pooraka and Rechaka are not simple Shwasa and Prashwasa but something more. In Pooraka the lungs are filled with air in measured and rhythmic way in a very slow process. Similarly in Rechaka lungs are emptied of air in a regular, rhythmic and measured way.
When we hold our breath in Antrlk Kumbhaka, we expand our lungs and fill pure air in them. The pure air is therefore able to reach each and every cell. The cells of the lungs get purified and strengthened in this way. When we do Bahya Kumbhaka, on the other hand, we retain the breath out. The cells of the lungs therefore contract and the impure air is squeezed out of them. This dual process makes the entire body clean, pure and light. This also increases longevity.
In simple breathing, we generally take the air in and then exhale it immediately thereafter. The pure air is therefore not fully utilized in the body. But Kumbhaka is the unique process which brings about its full utilization in the body. The importance ofKumbhaka is beyond words. It is common knowledge that when we want to do some work with all our force, such as lifting a heavy load-discus throw, etc., we usually hold our breath. It is therefore obvious that we can increase the strength and capacity of our body by Kumbhaka.
In fact, Kumbhaka is not difficult to perform because it only requires one to hold one's breath. But this does not mean that we should start doing it in an abnormal way. This can be risky or even dangerous. Increasing the period of Kumbhaka abruptly without sufficient prior exercise or doing it in an irregular and casual way can do more harm than good. It is therefore very essential that we should progress gradually and increase its practice by slow measures, so that we do not come to harm.
Nadi Shodhana Pranayama is an excellent Pranayama. It is very beneficial in the ailments of the nervous system, lungs and hypertension. In this Pranayama the centre of concentration should be Anahata Chakra (see next chapter for the description of Chakras).
Those suffering from high or low blood pressure should not do Kumbhaka in this Pranayama. They can however practise Pooraka and Rechaka slowly.
Kumbhaka should be done only after the disease has been completely cured, and then too in small measures.