Puraka is inhalation, Kumbhaka is breath retention and Rechaka is exhalation. This is a practice of breath control in Pranayam. The Hatha Yoga Pradipika states that the kumbhakas force the breath into the central sushumna channel, allowing kundalini energy to rise and cause liberation. In this breathing technique we isolate one nostril at a time. The ratio of the breath is 1:2:4. Close the right nostril with the right thumb, inhaling through the left nostril for four seconds. Then cover both nostrils, one with the thumb and the other with the little finger and hold the breath for eight seconds. Next, keep the little finger on the left nostril and release the thumb from the right nostril as you exhale for sixteen seconds. Then repeat the process, starting again from the other side. Breath should be smooth. Do it with a flow and as a continuous cycle. If you can exhale for sixteen seconds, then you can build up and try next time with twenty seconds on exhale. The ratio is 1:2:4, so if you inhale for five seconds, then hold for ten seconds and exhale for twenty seconds. If the twenty second exhale doesn’t work or you need to count fast then it’s better to keep doing it for sixteen seconds. Build up gradually. Once twenty seconds work well then inhale for sixteen seconds, hold for twelve and exhale for twenty four. The next step would be thirty two seconds and eventually sixty four seconds in the end.