The object of pranayama practice is to emphasize the inhalation, the exhalation, or retention of the breath. Emphasis on the inhalation is called Puraka Pranayama. Rechaka Pranayama refers to a form of Pranayama in which the exhalation is lengthened while the inhalation remains free. Kumbhaka Pranayama focuses on breath retention. In Kumbhaka Pranayama, we hold the breath after Inhalation, after exhalation, or after both.
Exhalation (Bahya Vrtti)
Whichever breathing technique you choose, the most important part of pranayama is the exhalation. If the quality of the exhalation is not good, the quality of the whole pranayama practice is adversely affected. If you are not able to breathe out slowly and quietly, you are not ready for pranayama, either mentally or otherwise. If the inhalation is rough we do not have to worry, but if the exhalation is uneven it is a sign of illness, either present or impending.
Yoga’s essential aim is to eliminate impurities and reduce avidya [ignorance]. Through this elimination alone, positive results come about. It can be compared to a sewer pipe which has been cleared of all blockages wherein the water can freely flow through. If something in us is preventing a change from occurring, then we need to remove that obstacle before the change can take place. The exhalation is vitally important because it transports impurities from the body or apa, making more room for prana to enter.
Often when Pranayama is discussed, it is the holding of the breath that is emphasized. Yet the ancient texts talk about the total breath, not simply Kumbhaka or Breath Retention. The Yoga Sutra discusses the stages of breathing in this order of importance:
o bahya vrtti or exhalation as the most important
o abhyantara vrtti or inhalation as secondary
o stambha vrtti or breath retention
Warning: Yoga breathing exercises or pranayamas are very powerful exercises. Many people experience dizziness or may lose consciousness while practicing beginner or advanced breathing techniques. Practice all breathing exercises slowly and controlled. Perhaps ask a friend to stay with you when trying out a new breathing technique. In addition, you can also sign up for some breathing or Yoga classes and practice under supervision of an expert.
Reprinted from: Holistic-online.com (This website has a lot of good information on pranayama! ~IYM admin)