The power which infuses the physical body and provides it the enhanced strength, endurance and stability required to carry out the Will of the Divine Spirit is developed through the liberation and enhanced action of the Prana. The science of Hatha Yoga attempts this development through the use of Asana and Pranayama, along with specialised techniques known as “Bandhas” or “locks” which help direct the flow of the energy. Practitioners of yogic techniques such as Kundalini Yoga have as their stated goal the release of the coiled up, latent energy of the “kundalini” that resides in the Muladhara Chakra at the base of the spine, so that it rises through the various higher chakras and can eventually reach the 1000 petal chakra at the top of the head. Even those who practice purely physical culture through various forms of exercise and training are developing and focusing the pranic energy to infuse the physical instrument with life-force, intensity and the radiant glow of strength and health that accompanies the strong flow of the prana.
Sri Aurobindo observes: “It is the universal Prana, as the ancients knew, which in various forms sustains or drives material energy in all physical things from the electron and atom and gas up through the metal, plant, animal, physical man. To get this pranic Shakti to act more freely and forcibly in the body is knowingly or unknowingly the attempt of all who strive for a greater perfection of or in the body.”
Sri Aurobindo points out that the method used in the integral Yoga differs from that of normal physical culture, Hatha Yoga, or Kundalini Yoga, because it can be developed and moved by psychic and spiritual means of the development of the higher Will: “…but for our purpose it can be commanded by more subtle, essential and pliable means; first, by a will in the mind widely opening itself to and potently calling in the universal pranic Shakti on which we draw and fixing its stronger presence and more powerful working in the body; secondly, by the will in the mind opening itself rather to the spirit and its power and calling in a higher pranic energy from above, a supramental pranic force; thridly, the last step, by the highest supramental will of the spirit entering and taking up directly the task of the perfection of the body. In fact, it is always really a will within which drives and makes effective the pranic instrument even when it uses what seem to be purely physical means; but at first it is dependent on the inferior action. When we go higher, the relation is gradually reversed; it is then able to act in its own power or handle the rest only as a subordinate instrumentation.”
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 14, The Power of the Instruments, pg. 704