'Kapala' is a Sanskrit word; it means skull. 'Bhati' means to shine. The term 'Kapalabhati' means an exercise that makes the skull shine. This Kriya cleanses the skull. So this is taken as one of the Shat-Karmas (six cleansing processes in Hatha Yoga).
Sit on Padmasana. Keep the hands on knees. Close the eyes. Perform Puraka and Rechaka rapidly. This should be practised vigorously. One will get perspiration profusely. This is a good form of exercise. Those who are well-versed in Kapalabhati can do Bhastrika very easily. There is no Kumbhaka in this Pranayama. Rechaka plays a prominent part. Puraka should be done quickly and forcibly by contracting the abdominal muscles with a backward push. When you do Puraka, release the abdominal muscles. Some people naturally make a curve of the spine and bend their heads also. This is not desirable. The head and the trunk should be erect. Sudden expulsions of breath follow one another as in Bhastrika. To start with, you can have one expulsion per second. Gradually you can have two expulsions per second. To begin with do one round in the morning consisting of 10 expulsions only. In the second week, do one round in the evening. In the third week, do two rounds in the morning and two rounds in the evening. Thus every week, gradually and cautiously increase 10 expulsions to each round till you get 120 expulsions for each round.
It cleanses the respiratory system and the nasal passages. It removes the spasm in bronchial tubes. Consequently, Asthma is relieved and also cured in course of time. The apices of the lungs get proper oxygenation. Thereby they cannot afford favourable nidus (breeding grounds) for tubercle bacilli. Consumption is cured by this practice. Lungs are considerably developed. Carbon dioxide is eliminated in a large scale. Impurities of the blood are thrown out. Tissues and cells absorb a large quantity of oxygen. The practitioner keeps up good health. Heart functions properly. The circulatory and respiratory systems are toned to a considerable degree.