The posture (asana) for Yoga meditation should be steady, stable, and motionless, as well as comfortable, and this is the third of the eight rungs of Yoga
Ās = to sit and āsana can be understood in two ways: āsyate nenetyāsanam = by which one sits, meaning the body positioning and state of mind, or āste tra asmin vā etyāsanam = upon which one sits = Blanquette, deer skin, etc.
Āsanas are practiced to develop the ability to sit comfortably in one position for an extended period of time. Asana served as stable posture for prolonged meditation. More than just stretching, asana open the energy channels chakras and psychic centres of the body Asanas purify and strengthen the body and control and focus the mind. Asana is on of the eight limbs of classical yoga, which states that asana should be steady and comfortable, firm yet relaxed. When holding a yoga posture, make sure you can breath siowly and deeply, Go to your edge in the posture, holding where you feel a good stretch or your body working, but don’t feel pain, strain or fatigue.
Practiced for those physical culturists that wish to maintain the nervous and endocrine systems in excellent health, because through these two systems the health of the whole body organism can be secured. The aim of the cultural poses is to produce physiological balance in the different systems working in the human body, so that it can possess the best organic vigor. The other purpose is to train the spinal cord and the brain for the interaction of Kundalini.
For those spiritual culturists that wish to reduce the metabolic activity of their body to a minimum and thus get their mind freed from all physical disturbances so that it can be left to itself and be brought to a point of concentration required to reach Samadhi. The aim of the meditative āsanas is to offer a comfortable posture for Prānayāma, Dhāranā, Dhyāna and Samādhi. and in coordination with other Yogic exercises to help the student of Yoga in the awakening of Kundalini.
There are mainly 2 relaxative āsanas, shavāsana and Makarāsana on the abdomen. They are used in between practice of āsanas to relax all the body and to be aware of the happenings in the body after a particular posture. They can also be used for meditation (ie shavāsana). The only disadvantage is that one can fall asleep easily in this posture.