In Sanskrit, bandha means to hold, bind, or lock. Yoga bandhas are muscle contraction techniques done in a specific manner and during ineternal or external breath retention of pranayama breathing.
Yoga bandhas are an advanced technique used to restrict or enhance the flow of prana to desired regions. They are applied to a group of muscles in the abdomen, neck and/or pelvic floor.
BANDHA | बन्ध
YOGA BANDHA GUIDES
"Jalandhara bandha or the throat lock is a yoga technique of resting the chin on the chest to compress the upper esophageal sphincter during internal breath retention. It is first bandha ygois should learn."
"Uddiyana bandha or the abdomen lock is a yoga technique of pulling the navel in and up, towards the spine while holding the breath. You lift the diaphragm into the thoracic cavity while standing or sitting."
"Mula bandha or Root Lock is a yoga technique of contracting the cervix or perineum during pranayama while sitting in Siddhasana. Contract the anal sphincter during breath retention and release gradually."
Prana Picks: Yoga Books
The Great Lock Technique
The Maha Bandha, called the 'giver of great powers,' is one of the most advanced yoga techniques mentioned in the Hatha Yoga Pradipika. It is a combination of the three primary body locks applied simulatneously to control the flow of prana in the body.