Instead of increasing the speed of breathing than the normal 16 to 18 breaths, we can reduce it up to 3 breaths per minute. This is achieved by increasing the time of inhalation and exhalation.
Normally the inhalation and exhalation time is 2 seconds each. If you control the breath & increase the time of inhalation and exhalation up to 6 seconds each, then the speed of breathing will be 5 breaths per minute. If you increase this time to 8 seconds then breathing will drop to 4 breaths.
This is called the deep breathing and is very effective as it supplies more oxygen to the lungs for blood purification while consuming less energy.