Hello Rutger,
in order to the question of energy in yoga I have noticed that a yoga āsana with the same perfection can show differences in expression. Some yoga postures demonstrates more the physical force, others express lightness, dynamics, and centering.
I found a first explanation of these phenomena in the writings of Heinz Grill (have a look at my book recommendations). Heinz Grill distinguishes three types of energies, one that comes from the physical body (kāma), one that comes from the vital body (prāṇa) and one that comes from the mind (buddhi).
The most important energy field in yoga is the prāṇa energy of the vital body. This can either be stimulated more by the physical body or more by the thoughts. With regard to a positive inner development, he advises a mindful pracice, but not to take so much importance to the physical level of energy. It would be more important if the prāṇa energy is attuned to certain meditative thoughts.
This probably means Umesh when he says that you want to bring the energy to a higher level.
Heinz Grill concludes that during yoga exercises, you should allow to the breath to flow as freely as possible so that the body experiences no manipulation and interference. At the same time he gives concrete ideas in his books, with which one can accompany the practice and which, in sum, produce a luminous and light energy level.
If you want to become aware of this possibility of lightness in yoga, you can have a look at this video. It shows the scorpion, which is an advanced yoga position.
Alina
