The various techniques of Hatha yoga have powerful effects on the production and circulation of pranic energy in the body. The bandhas are a means of controlling and directing this energy. The word bandha means “to lock” or “to restrain.” It describes well the action of bandhas; they lock or restrain the prana. They are essential to the advanced practice of Hatha yoga. Without them, the energy produced by the practice cannot be properly utilized.
All bandhas involve muscular contractions, but this is only one aspect of them, and the ancient yoga texts list bandhas among the most important Hatha yoga techniques. Practiced with pranayama or in isolation, the bandhas work with the organs and the nervous and endocrine systems. They can help to ease disorders of the reproductive and urinary systems, sexual dysfunction, back problems, and recovery after childbirth.