NOULI

Nauli is an abdominal kriya in which isolated contraction and rolling manipulation of the abdominal recti muscles (rectus abdominis) which form the front linear wall of the abdominal cavity, are accomplished. The following are preparatory for Nauli.

A.  Uddiyana  Bandha and Agnisára

Sthiti: Tádasana
Practice
Stand with the legs 2 to 3 feet apart, bend forwards slightly from the waist and place the palms on the thighs with the arms straight.
Make yourself quite comfortable in this position.

Stage  I:   Uddiyana Bandha
Exhale completely through the mouth by vigorously contracting the abdominal muscles. 
Simultaneously press the hands against the thighs, tighten the arms, shoulders, neck muscles and lift up the ribs.
As a result of this, the diaphragm automatically rises up, producing a concave depression of the abdomen. The abdominal wall gets sucked in  as if to press the spine.
Hold this condition as long as comfortable.
Then inhaling slowly release the abdominal muscles and return to the upright position.
Rest for a while and then go for the next round.
Repeat 5 rounds.

Stage II:  Agnisára

In the position of Uddiyána Bandha, move the abdominal wall in and out vigorously like a pump  as many times as you can  (while holding the breath in exhalation).
This movement of the abdominal wall is done through mock inhalations & exhalations i.e., it seems as if one is inhaling and exhaling whereas it is not so.
Then stop the movement of the abdominal wall, release the bandha and while inhaling come up to Táãásana  and relax.
Repeat  a few times.

BENEFITS
It massages the abdomen, stimulating the associated nerves, strengthening the muscles and encouraging optimum health of the abdominal organs.
It improves blood circulation to the whole trunk area and strengthens all the internal organs.
It is a panacea for many abdominal & stomach ailments including constipation, indigestion, and diabetes.
The digestive fire is stimulated nicely.
It can also alleviate depression, dullness and lethargy.

B.  Madhyama Nauli

l     Maintaining Uddiyána, give a forward and downward push to the abdominal point just above the pelvic bone in the mid-line, where the two recti originate. This push brings about the contraction of these muscles which stand out in the center, leaving the other muscles of the abdominal wall in a relaxed condition.

C.  Daksina and Váma Nauli

For Dakúiïa (right) Nauêi, one has to contract the right rectus alone leaving the other muscles including the left rectus relaxed.
For Váma (left) Nuaêi, only left rectus is contracted leaving the others relaxed.

D.  Nauli Cálana
When one has gained full control over these three types of Nauli, rolling of the recti muscles clockwise and anti- clockwise is practised. This is called nauli cálana.    

Benefits
Stimulates and activates the abdominal organs. Stimulates  the intestines. tones up recti muscles, helps to relieve constipation, piles and gastritis.

Limitations 
Avoid in cases of acute ulcers in stomach, for one year after abdominal surgery,  people with weak lung efficiency try under expert guidance. Avoid in hypertension, ischaenic heart diseases, severe back ache and hernia. Avoid during menstruation.