Bandhas - Overall, most of us know that core stability offers functional strength in yoga and everything else we do in life and play. An integral part of the Astanga yoga practice, the bandhas are often elusive. General questions of What? Where? When? Why? How? usually turn into too much thinking, when it's much more subtle. After all, they need to be engaged throughout the entire practice. Bandhas initially are thought of as contracting certain muscles to encourage a 'gripping' sensation. But as the translation of bandha as "a lock" at first makes us contract & hold, we must realize it more directly un-locks the pranic flow of energy, directing it upward. MulaBandha assists at the pelvic floor region, providing a firm foundation of root/mula energy, while the UddiyanaBandha assists the abdominal region to send that energy upward into the nadis/energy channels. In short: base energy given flight. The result is one that combines both strength & lightness in the practice. Applying mulabandha & uddiyanabandha allows you to move with more control and more freedom. The Astanga system's tristana (bandhas/dristi/vinyasa breath-movement) markedly sets it apart from other styles. It is due to this state of tristana that Astanga is often referred to as a moving meditation.
Certain surefire techniques to begin to learn & locate bandhas include the preparation for nauli kriya. David Williams loves this and readily teaches it as a tool to guide the student to uddiyanabandha & mulabandha: standing and leaning with hands on knees and straight arms, exhale fully and hold, while you draw the abdomen in & up, almost vacuum-like. In the actual Astanga practice it is more subtle than that, as we keep the breath moving, but nauli prep lets the mind and body wrap around that idea of stillness at the belly. Specific asana also assist in pinpointing the desired feel of bandhas engaged, such as downward facing dog/adho mukha svanasana: the region of the abdomen automatically hollows out and we can direct breath more easily into the ribcage rather than the belly. JalandharaBandha assists the upper throat-chin lock but is very subtle during the asana practice to ensure controlled pranayama and neck alignment. Here again, downward dog can give guidance to locating jalandharabandha especially when nose/navel dristi is applied.
Bandhas are integral components of ujjayi pranayama as well, working in tandem. The great deal of prana we are delivering to the body, is also offered bandha support and guidance. From the start, the sun salutation/surya namaskara sequence gives rise to all elements...dristi, ujjayi breath & bandhas coalesce and we are supported and lifted and present.