Bandhas in Yoga Practice are used to unblock the free flow of Prana (energy) along the Sushumna Nadi. There are essentially 3 "Psychic Knots" called "Granthis" that can be transcended by the use of Bandhas. >>The first "Granthi" is "Brahama" it is located at the base Chakras Mooladhara & Swadhisthasina. It is linked with the survival instinct, urge to procreate, deep instinctive knowledge, awareness and desire! When the Brahama Granthi is transcended the primal energy = Kundalini can rise above the Chakras and this aids in avoiding attractions and personality. >>The second "Granthi" is "Vishnu" it is associated with the Manipura and Anahata Chakras. The Manipura Chakra is key to the energy, digestion and metabolism in the body. Anahata Chakra is the heart and emotions. When the Vishnu Granthi is transcended one is no longer bound by physical, mental and emotional attachments. >>The third