The Physical body is the base for the spiritual journey according to BKS. Iyengar. Putting the physical body into different shapes like asana, different quick and unnatural stress like Kriyas and focusing point like Drishti is the basic step of the spiritual journey. Gravity is a continuous force acting on the body and ground is the base for the physical body which are to be understood and analyzed for the smooth conduct of Yogic practices like asana, kriya, Drishti, bandha, mudra, chanting, meditation etc., The gravity at the center of the body weight (Center Of Gravity) that is at S2 (2nd Sacral vertebra) pulls vertically down onto the ground (Base Of Support) with an imaginary line (Line Of Gravity). Teachers have to remember these techniques to adjust the body parts and prevent falling and injuries at the learning stage. The base of support as the ground for our physical activity is constant. But still, if the support is required during the initial stage of training, there are two ways. One is external support like using straps or belts or ropes or blocks or pillows or manual support from peers, teachers, friends etc., Second is internal support like using some more muscles for holding or gripping the own body parts. Later on, perform the pose without internal and external support but adopting a Mudra (Hand gestures) to feel the pulse at peripheral parts of the body. This way the asana practices takes a person from physical level to mental level through breathing. This is the initial part of the spiritual path. The gained knowledge and awareness is the intellect which can overcome the mind and allows it to sublimate the emotions at different situations of life. This internal awareness and self-satisfaction is the state of contentment in front of wise person and silence in front of the ignorant person. At this level of existence, body will mold in different ways without much effort as before. These are the steps of transformation.
Here is the teacher training on Asana and its progress;
Meaning: Expression through shoulders as a communication to outside world. This is also called as cobra pose, because it uses the upper body for expression.
Muscle work: All the extensors of vertebral column and upper limb muscles to support the weight of the upper body. Hence these muscles are going to be stronger later.
Base of Support: Area between two palms front, two lower limbs until toes makes a long triangle shape. As the muscle strength improved, slowly reduce the usage of hands by taking them closure towards lower ribs then later on, no more weight on hands makes short triangle than before.
Fig-1: Much weight on hands Fig-2: Less weight on hands
Process of transformation: This asana strengthens the upper body and the ribcage muscles which are skeletal muscles. Later force or energy will be distributed towards smooth muscles of upper body like respiratory tract, mouth to stomach and cardiac muscle. Later the inner most organs like glands will be acting accordingly and gets control on Homeostasis, in spiritual language Chakra of each part of the middle body. These all improves the awareness and helps the person in the realization. Benefits are from physical level (little part) to spiritual level (beyond physical world).
Moral: Asana has to be a first step of spiritual journey rather than the outward performance towards the competitive world. Here is the one variation of Bhujangasana.
Fig-3: One variation of Bhujangasana