Yoga Postures (Asanas)
The basic premise behind Hatha Yoga theory is the unity of the processes of the mind and body. Hatha Yoga (forceful or physical yoga) works with the physical body to initiate changes in the mind.
One such practice of Hatha Yoga is asana practice (yoga poses or postures). Asana practice, along with pranayama (breath control/techniques) works with the general health of the body-mind. Asana practices massage the body's internal organs, re-oxygenates the blood (through breath work), improves circulation and strengthens and tones the body, it also works to improve the body's immune system.
Asanas vary considerably between different yoga schools and traditions. Where Iyengar tends to be a more dynamic practice, Integral Yoga works with the body's endocrine system - stimulating the glands and strengthening immunity. Other schools of Yoga use their own unique blend of poses created from the wisdom that is yoga.
Asanas should never cause pain. The general rule is: if it feels good, it probably is good. If it feels bad, it probably is bad. A good yoga teacher will take the basic poses and modify them to suit the age, health status and flexibility of their students. Every yoga asana can be performed in a variety of ways, depending on the result required. Where one may do the Cat Pose is dynamically aiming at stimulating circulatory system along in the spine, another approach might be to do this pose gently to relax the spinal column - reducing tension and gently massaging the nerve endings of the spine. No matter what the ultimate goal of the pose, it will undoubtedly give more benefits than originally aimed for - that is the nature of Yoga.
An Important Message: read this before attempting the following asanas.