Meditative aasanas provide broad triangular base for the body, formed by two knees and the pelvis. 

This broad base gives firm foundation to the body and makes it steady and stable. Even if one looses the awareness of one's own body during meditation, he remains balanced due to sub-conscious control of the posture by the lower brain centers.

The spine is kept in vertical and straight position and any extra curvature in the backbone is consciously avoided.

The four natural curves are however, well preserved. This is very important for higher spiritual practice. 

Straight spine prevents compression of the abdominal organs and keeps the abdominal muscles free for breathing activity.

It facilitates easy movements of diaphragm during breathing.

The functions of the digestive organs including peristaltic movements are carried out smoothly. 

A well balanced straight spine requires negligible activity of the flexors and extensor muscles of the trunk to maintain the balance of the spine. 

This is sufficient to keep the participant semi-conscious and to avoid sleeping during an aasana. 

These postures are devised so as to induce varying degrees of mental and physical relaxation besides other desired effects. 

Thus they are methods of achieving perfect mental and physical relaxation. Therefore, these aasanas may be practiced as a means of reducing the stress of the daily life of the modern society. 

Besides providing suitable body postures, aasanas are conducive for Dhyana and Samadhi (meditative aasanas) or their role in developing the physique (cultural aasanas). The practice of aasanas bring about a number of physiological, biochemical and psychological changes in the body. 

Among such changes reduction in body weight, increase in rate of respiration, sheer expansion, increased vital capacity, reduction in blood sugar and serum lipid levels, increase in serum proteins, improved adrenocortical functions and certain improved adrenocortical functions viz, performance quotient, memory quotient, reduced mental fatigue and reduced neuroticism index accompanied by conforming electrophysiological and neurohumoral changes are notable.