A lot of people consider the Asanas to be true gymnastic exercises and they perform them as such. Leaving aside the therapeutic aspect, the Asanas can be practiced to maintain the normal state of physical and mental health or to progress in yoga, but nevertheless they differ in various aspects from the common physical exercises.
From the moment that the objectives of the Asana and those of common physical exercises are different, the formalities of execution must be different too. The movements to stand in an Asana or to go out of a yoga pose are slow but stable, and the execution is made with gentleness. In reality the phase of maintenance of the Asana is more important than the movements themselves (to notice that the slow movements also ask for participation of deep muscles).
The common exercises are performed in a rapid, jerky, way and they provoke tiredness or exhaustion of energy. The phase of maintenance (static phase) is rarely present and nonetheless is of brief duration: this means that only the superficial muscles participate to the execution.The effects of the Asana concern above all the trunk, where mainly operate the proprioceptor and visceral receptor mechanisms.
When the specific postural models of the asana are maintained for some time, they produce changes of pressure in the inside hollow of the visceral organs, which influence the circulation in the abdominal zone.
The nervous roots of the abdominal region are revitalized. In the common exercises the movements of the extremities are more important than those of the trunk. This type of exercise acts above all on the superficial skeletal muscles and on their nerves. The peripheral circulation increases. The quickly performed movements are repetitive.In the Asana the movements of the vertebral column are done in almost all directions. The vertebrae, in fact, are not compressed in only one direction, but stretched in four directions and also submitted to the movement of rotation.
For every movement of the backbone, in the Asana there is a contrary-movement. The deep muscles of the vertebral column and ligaments are put in action. In the common exercises, as a rule, there is repetition of a particular movement to develop the strength and the dexterity of a specific part of the body.
In many exercises is developed or conditioned in asymmetrical way only one side of the body.In the Asanas the objective of muscular expansion is excluded: heavy muscular activity is avoided and accordingly the waste of energy is inferior to that of ordinary physical exercises. This excludes every tiredness of the cardio-respiratory mechanisms; in fact, tensions operating on various levels are reduced.