In Sanskrit. Kapal means "skull" and "bhati" means "illuminating". The increase of oxygen and prone illuminates the skull, face, and skin! It's purifying for the frontal brain, as well.
Part of the yogic principles of the body cleansing techniques - shatkarma. Therefore, it's cleaning as well as breath work.
You focus on the exhales instead of the inhales (inhales happen naturally)
Traditionally done for 3 rounds for 30 pumps of breath each round.
A very meditative practice - aligns both hemispheres of the brain.
