A disease-free system should be the starting ground for yogasanas and pranayama. There are six specific cleansing techniques, known as Shat Kriyas, which eliminate impurities and help cure many ailments. Of these, the following four can be practised safely.

Jalaneti :

Most diseases of the nose and thraot are caused by the accumulation of impurities in the nasal passage. Jalaneti is a process of cleansing the air passage of the nostrils and the throat by washing them with tepid saline water. Take a clean jalaneti pot. Put half a teaspoonful of salt in the pot and fill it with lukewarm drinking water. Stand up and tilt your head slightly to the right. Insert the nozzle of the pot in the left nostril and let the water flow into it. Inhale and exhale through the mouth, allowing the water to flow out through the right nostril. Reverse this process by tilting your head to the left and letting the water flow from the right to the left nostril.

Jalaneti should be practised only in the morning. It will relieve sore throat, cold, cough, sinusitis, migraine, headache and cases of inflammation of the nasal membranes. It keeps the head cool and improves vision.

Vamana Dhouti or Kunjal :

This is a process of cleansing the interior of the stomach. Drink four to six glasses of tepid water, with a little salt added to it, early in the morning on an empty stomach. Then stand up, bend forward, insert the middle and index fingers of the right hand into the mouth until they touch the uvulva. Tickle it until you feel a vomiting sensation. The saline water thus ejected will bring up bile and other toxic matter with it. Repeat the process till all the water is vomitted out. This should be done once a week or as and when necessary.

It is beneficial for cleansing the stomach in cases of excessive bile, constipation, and gastric troubles. Persons suffering from hyperacidity should perform kunjal with unsalted water. It gives relief from headaches, nervous weakness, chronic cold, cough and asthma. It should not be practised by those suffering from high blood pressure, ulcers and heart trouble.

Kapalbhati :

Kapala means 'skull' and bhati means 'shine'. This is a respiratory exercise for the abdomen and diaphragm. The channels inside the nose and other parts of the respiratory system are purified by this exercise. In the process, the brain is also cleared.

Sit in a comfortable position, preferably in padmasana. Exercise the diaphragm by exhaling suddenly and quickly through both nostrils, producing a hissing sound. Inhaling will be automotive and passive. The air should be exhaled from the lungs with a sudden, vigorous inward stroke of the front abdominal muscles. The abdominal stroke should be complete and the breath should be expelled fully. While inhaling, no willful expansion is necessary and the abdominal muscles should be relaxed. This exercise should be done in three phases, each consisting of 20 to 30 strokes a minute. A little rest can be taken in between . Throughout, the throacic muscles should be kept contracted.

Kapalbhati enables the inhalation of a good amount of oxygen which purifies the blood and strengthens the nerve and brain centres. This kriya provides relief in many lung, throat and chest diseases like chronic bronchitis, asthma, pleurisy and tuberculosis.

Trataka :

In yoga, four exercises have been prescribed for strengthening weak eye muscles, relieving eye strain and curing of eye disease. They are known as ' Trataka ' ,which in sanskrit means ' Winkles gaze at a particular point." or looking at an object with awareness. The four tratakas are : Dakshinay jatru trataka in which, with face forwards, the eyes are fixed on the tip of the right shoulder ; Vamajatru trataka, in which the eyes are fixed on the tip of the left shoulder ; Namikagra trataka, in which the eyes are focussed on the tip of the nose, and Bhrumadhya trataka, in which the eyes are focussed on the space between the eyebrows.

These exercises should be practiced from a meditative position like padmasana or vajrasana. The gaze should be maintained for as long as you are comfortable, gradually increasing the period from 10 to 20 and then to 30 seconds. The eyes should be closed and rested after each exercise. Persons with acute myopia should perform the tratakas wit h their eyes closed.