Rapid performance of Recaka (exhalation) and Puraka (inhalation)like (emptying and filling up on of) the bellows of a blacksmith is Kapalabhati, well known as the destroyer of disorders caused by phlegm.
Note: This is one of the six cleansing processes of hathayoga.
This is related with the respiratory system
Spreading out comfortable `Asana` (sitting material like blanket, kusha, deer skin or towel), sit in Padmasana, Samasana, Svavtikasana, or in any comfortable posture. While doing kapalabhati, there is a chance of shakening the body with jerk hence sit firmly. As the bellows of the blacksmith draw air in or leaves air out with sound, so we have to practice inhaling through nostrils and exhaling forcibly soon, keeping our mouth closed. The navel region is drawn in during each exhalation and bulged out at the time of inhalation. This is to be practiced repeatedly, righty and rapidly. Here exhalation is given prominence, inhalation takes place automatically.
5 times. Each for 09-10 minutes. Later on increase the time up to 15-20 minutes maintaining the final position and reduce the repetitions.