1. Madhyama nauli (central contraction)
Take the correct standing position.
Exhale deeply, emptying the lungs as much as possible.
To obtain the fullest exhalation you should contract the abdominal muscles by doing uddiyana bandha.
Look at the abdomen.
Hold the breath.
Try to contract the rectus abdominii muscles so that they form a central arch running vertically in front of the abdomen.
This position is clearly shown in the figure.
Hold the contraction for as long as you are able to comfortably retain the breath.
Try to contract the muscles as much as possible, but don’t strain.
Then relax the muscular contraction so that you return to uddiyana bandha.
Breathe in slowly and let the abdomen expand.
Relax your whole body.
This is 1 round.
Breathe normally a number of times, allowing the pulse beat to return to normal.
Then repeat the practice.
You should practise madhyama nauli until it is perfected; this may take a number of weeks, or even months.
Then proceed to vama nauli.