Pranayama is the process of yogic breath or science of breath. As stated in Yoga Sutras, ‘tasmin sati shwas prashwas yorgati vichchhedah pranayamah’, that is pranayama is related with Prana, which means breath, respiration, life, vitality, wind, energy or strength. The suffix ‘Ayam’ means length, expansion, stretching or restraint. Pranayama thus means the extension of breath along with its control.
Every breath has three components:
(1) inhalation or inspiration, which is termed Puraka (to fill),
(2) retention or holding the breath, a state where the inspired air is held in the lungs, termed Kumbhaka, and
(3) exhalation or expiration, which is called Rechaka (to empty), in which the air filled in lungs is to be released quietly.
There are two states of Kumbhaka, Abhyantar Kumbhaka and Bahya Kumbhaka. In the Abhyantar Kumbhaka the seeker (Sadhak) witholds the breath while he is in the stage of Puraka, and in Bahya Kumbhaka he witholds the breath in the stage of Rechaka.
In pranayama there is a measured timing ratio for the three stages and the ratio should be carefully observed.
In yogic breathing, inhalation (Puraka) consists of muscular action. The movement has two parts working together. In the first part the thoracic cage expands to make room for lungs to inflate. In the second part the dome-shaped diaphragm flattens out and descends, swelling out the abdomen and, incidentally, massaging beneficially the abdominal viscera. Now one should breathe deeply, pour air into the lungs, but the point at which the inflation and expansion ends should be just before the point at which discomfort intrudes. If one sits easily, with the back straight and in the level of head, the respiratory muscles will be free to expand and recoil in comfortable pranayama.
Holding the breath is a conscious act that checks the mechanism, whereby our respiration is automatically regulated. With conscious suspension of breath (Kumbhaka) we just switch from ‘automatic’ to ‘manual’, as it were. This requires some practice for smoothness and ease. This means refraining from forcing, and making comfort the criterion. When Kumbhaka follows filling of the lungs, the thoracic umbrella must stay open, diaphragm down and the abdomen out during the immobile breathing pause. One has to inhibit the initial tendency of the ribs and diaphragm to recoil during the full pause, and to expand and rise respectively during the empty pause.
However after some weeks of training, inhibition becomes effortless as long as Kumbhaka is not prolonged to a point of strain. During Kumbhaka with full lung or empty lung, one should resist the temptation to let a little air through the nostrils or mouth to keep the suspension going comfortably. The abdomen should not change the tone by contracting or relaxing. Yogic breath suspension (Kumbhaka) achieves both physiological and psychological benefits. The pause gives more time for gaseous exchange (02 : CO2) across the blood capillaries. In addition, it allows better mixing of fresh air with the stale residual air in the air sacs of the lungs. Holding of breath, during the period lungs are filled, has a cleansing and purifying effect on the residual air.
In pranayama, comprehensive time is allocated to empty the lungs as to fill them. Carbon dioxide — the waste product that all the cells of the body exchange for fresh oxygen every three minutes — is expelled from the body with the outgoing breath. Some residual air remains, as mentioned earlier. The more complete and efficient ihe exhalation, the more efficient the purification, and the greater the lung expansion and inflow of fresh air and oxygen on the following inspiration.