This exercise called the Bellows Breath or Bhastrika. It’s used to raise vital energy and increase alertness.
Bhastrika consists primarily in forced rapid deep breathing, which serves as a basis for many varieties of exercises. Although air is forced both in and out, emphasis is placed upon expulsion or explosion of air. A series of such explosions, each following the other in quick succession without pause, either full or empty, may be called "a round."

Beginners should limit a round, though the number may be increased to ten or fifteen, or to any number needed to obtain the desired effect.

The breath-stroke in the rapid succession of breaths may or may not be very deep, but it is customary to finish or follow a round by the deepest possible inhalation and exhalation. A series of normal breaths should occur before undertaking a second round.

• Inhale and exhale rapidly through your nose, keeping your mouth closed but relaxed. Your breaths in and out should be equal in duration, but as short as possible. This is a noisy breathing exercise.
• Try for three in-and-out breath cycles per second. This produces a quick movement of the diaphragm, suggesting a bellows. Breathe normally after each cycle.
• Do not do for more than 15 seconds on your first try. Each time you practice, you can increase your time by five seconds or so, until you reach a full minute.

The desired effects range from increased ventilation, increased blood circulation, increased clearing of nasal passages and increased thinking capacity to overwhelming pacification of all mental disturbances. Boosts the supply of oxygen and purifies blood. Helps to keep negative thoughts away.

You should exercise caution against the temptation to go to excess in initial bellows experiments. Excess of air may induce temporarily feeling of dizziness, drowsiness, lightheartedness, giddiness or a feeling of floating in the air.