Using the Bandhas
Bandhas are energetic locks that contain the prana in the torso and concentrate it in the three main energy channels (nadis) of the body. Bandhas can be performed in a physical and external manner engaging the skeletal muscles; it can also be felt as a subtle and internal energetic process. Bandhas are practiced individually at first, and then they can be incorporated with asanas, pranayamas and eventually mudras.
Mula Bandha, the Root Lock
To engage mula bandha, exhale and contract the muscles between the pubic bone and the tailbone, pulling the perineum up in towards the abdomen. As you pull the pelvic floor up, feel the lower deep abdominal muscles engage and pull towards the spine. Initially you will need to contract the anus and the genitals, but over time work on relaxing these areas and isolate the perineum (the space between the anus and genitals). Mula bandha can be engaged from 15 to 100% of the contraction and can either be held for as long as possible or used by rhythmically engaging and releasing the contraction with the breath. Do not strain while holding, or hold the breath in or out when engaging mula bandha.
Using mula bandha with yoga postures has many benefits. It helps build core body strength, enables you to hold the postures longer, protects the low back muscles and makes the postures safer. Mula bandha also increases your energy and vitality, and improves concentration and mental clarity. Using mula bandha to support the asana from your core body allows the distal muscles to relax, enabling the body to use less energy to hold the posture. Mula bandha can be engaged in most yoga postures, but is most importantly utilized in back bending postures such as standing back bend, cobra, crab, bridge, up dog, boat, and camel.
Uddiyana Bandha, the Abdominal Lock
To practice Uddiyana Bandha, come into a comfortable siddhasana or sukhasana cross‐legged seated position with the palms facing down on top of the knees. Let the eyes softly close and the breath slow and deepen. Quickly exhale all of the breath out through the nose, lean forward, press the palms into the knees, and engage the abdominal muscles to strongly pull the belly in and up under the ribcage. Hold the breath as you hold the abdominal lock for as long as comfortable. To release, soften the abdominal muscles, lean back and very slowly take a breath in through the nose. Take a few slow deep breaths in and out and let your breath return to normal before practicing additional rounds. Begin with practicing three rounds and you can slowly increase it to up to ten rounds over time.
Uddiyana Bandha (literally, “flying upward” lock) strengthens the digestive fire and tonifies the body's energetic core. The abdominal organs are massaged, toned and purified and the adrenal glands are balanced by the abdominal contraction. Uddiyana Bandha is contraindicated in high blood pressure, heart disease, glaucoma, and pregnancy. To increase the benefits of Uddiyana Bandha it can be combined with Nauli shatkarma. Uddiyana Bandha is also be combined with Mula and Jalandhara Bandas to create the great lock, Maha Bandha.
Jalandhara Bandha, the Chin or Throat Lock
To practice Jalandhara Bandha, come into a comfortable siddhasana or sukhasana cross‐legged seated position with the palms facing down on top of the knees. Let the spine be long, the shoulders relaxed down and the sternum lifted. Let the eyes softly close and the breath slow and deepen. Take a slow deep inhale to two thirds of your lung's capacity and hold the breath in. Drop the chin to the chest and draw it in so the back of the neck stays long and does not round. Let the shoulders roll very slightly forward to deepen the lock in the throat, but keep them soft.
Hold the abdominal lock for as long as comfortable, without strain. To release, bring the chin up first and very slowly take a breath in through the nose. Take a few slow deep breaths in and out and allow your breath return to normal before practicing additional rounds. Begin with practicing three rounds and you can slowly increase it to up to ten rounds over time. Jalandhara Bandha regulates the circulatory and respiratory systems, stimulates the thyroid to balance metabolism, and is said to cure all diseases of the throat. Jalandhara Bandha is contraindicated in high blood pressure and heart disease. Jalandhara Bandha is also be combined with Mula and Uddiyana Bandas to create the great lock, Maha Bandha.
More info: http://www.yogapoint.com/info/bandha.htm and Divine Alignment by Guru Prem Singh Khalsa, www.divinealignment.com