Exhaling the Stale Air

First, sit in Vairocana posture which has seven characteristics:
I. Legs crossed."
2. Hands on the knees 
3. Tongue resting against the palate.
4. Eyes, lips and teeth naturally closed.
5. Back erect, straightening the spine to form an alignment straight as an arrow from nose to navel
 6. Chest and shoulders open.
7. All parts of the body relaxed and at the same time under control.

To begin, take a deep breath gradually filling with air from the bottom upward, starting from the area below the navel. Simultaneously, slowly raise your right arm and shoulder elevating the elbow. Then, with the palm facing outwards, close the right nostril with the ring and middle fingers and exhale the stale air slowly and directly through the left nostril.  Perform the same exercise on the left side so as to exhale the stale air through the right nostril. Females should do the exercise starting from the opposite side, first raising the left arm.  Alternate sides for a total of six breaths. On the seventh breath, keeping your hands on your knees, inhale opening your chest and shoulders well during the last part of the inhalation. Then, exhale through both nostrils, first emptying the upper part of your Lungs and, in order to exhale completely the stale air, finish the exhalation by bending forward until your forehead touches the ground.  Inhale deeply and directly, keeping your back straight as you slowly raise yourself up. Again slowly exhale the stale air as in the previous phase. Repeat these phases of inhaling and exhaling through both nostrils for a third time. In this way, nine cycles of breathing are performed, which is why this exercise is called the ninefold exhaling of the stale air. The expression `directly exhaling the stale air' has been used to distinguish this type of breathing from indirect or sounded exhalation. In fact, the indirect exhalation is done by constricting the glottis and produces a distinct HUUUN sound by not allowing the air to flow out directly. Thus if we put our hand under our nostrils, we will feel only a warm current. Conversely, the direct exhalation does not produce this sound, and when it is forceful we will feel the flow of air from the nostrils down at the level of the navel.  As with exhalation, the inhalation too can be done directly or indirectly, and it is very important to understand their distinctive features in order to be able to apply them as necessary without confusing them.

Chogyal Namkhai Norbu. Yantra Yoga: The Tibetan Yoga of Movement