Rules for Practicing Asanas

Take a full bath (Vyápaka Shaoca) before practicing ásanas. Vyápaka Shaoca must also be performed before daily meditation. However, if ásanas are combined with daily meditation, it is unnecessary to do vyápaka shaoca separately.
Do not practice ásanas in an open area because exposure to sudden changes in the temperature may cause one to catch a cold. When practicing ásanas indoors, keep the windows open to allow air to circulate.
No smoke should be allowed to enter the room: the less smoke, the better.
Males must wear tight-fitting underwear. Females must wear tight-fitting underwear and a bra, tight-fitting exercise clothing.
Practice ásanas on a blanket or a mat. Do not do ásanas on the bare ground because you may catch a cold, and some secretions which come from the body while practicing ásanas may be destroyed.
Practice Ásanas only when the breath flows through the left nostril, or both nostrils, not when the breath flows only through the right nostril.
Take Sáttvika food (Sentient food). But a person for whom it is difficult to give up Rájasika food can, for the time being, take a small piece ( 1/4 of the nut) of myrobalan, or something of a similar nature, after meals. However, this procedure does not apply in cold countries.
Do not cut the hair on the joints of the body.
The nails of the fingers and toes must be kept cut short.
Do not practice ásanas on a full belly. It is prohibited to perform ásanas for 2 ½ to 3 hours after a meal.
After practicing ásanas, massage the arms, legs, and entire body, especially the joints, very well.
After the massage is finished, remain in Shavásana (corpse posture) for at least 2 minutes.
Avoid water contact for ten minutes after Shavásana.
A practitioner of ásanas should not massage his or her body with oil. If you really would like, you may rub only a little oil lightly over the body.
After practicing ásanas, it is desirable to walk in a solitary place for some time.
Práńáyáma is prohibited immediately after ásanas.
If one must go outside after practicing ásanas and the body temperature has not returned to normal, or if there is any difference between the room temperature and the outside temperature, one must cover the body. If possible, take a deep breath inside the room and exhale it as soon as you step outside. There will be no chance of catching a cold this way.
18. It is not forbidden for ásana practitioners to engage in free-hand exercise, running, or sports, but all of these activities are prohibited immediately following ásanas.
There is no restriction of the nostril for the following ásanas: Padmásana (lotus posture), Siddhásana (Siddha posture), Ardhasiddhásana (half Siddha posture), Bhojanásana (cross-legged sitting posture), Viirásana (Viira posture), Diirgha prańáma (long bowing posture), Yogásana (yoga posture) and Bhújauṋgásana (snake posture).
For all those ásanas where there is no restriction of nostrils, there is no restriction on food.
Women are not permitted to practice ásanas or any other form of exercise during menstruation, pregnancy, or within one month of delivery. The ásanas for dhyána (meditation) can be done under all conditions – Padmásana, Siddhásana and Viirásana are the proper ásanas for Dhyána and Dhárańá.