The postures of Astanga yoga are so impressive that we sometimes tend to get carried away with the details of the technique to the exclusion of all else. The core principles that underpin this practice are the combined use of a steady, regular ujjayi breath, muscular locks called bandhas, the connecting of breath and movement in vinyasa and the steady point of focus known as drishti. The combination of these powerful techniques is called tristana and it provides the framework for your practice. Although these are all elements practised in other forms of yoga, their combination and emphasis in this practice make it unique. It is these elements that differentiate an Astanga yoga practice from what would otherwise be a kind of stretching or gymnastic routine.
The cleansing and purifying nature of heat during yoga practice, referred to as tapas, is a concept that appears in various different styles of yoga and in many yoga texts. In some styles of yoga, the practice room is heated to a high temperature. In Astanga yoga, it is thought that heat must be generated from within.
The heat generated when you practise Astanga yoga is said to have a strong cleansing and purifying effect on your body, and to burn away mental, emotional, physical and spiritual debris. Heat comes from three sources: the athleticism of the movements themselves, the fast-moving pace of an Astanga yoga series and the combined use of ujjayi breath and the bandhas.
On a physical level, heat quickly makes your body much more flexible. When your muscles and joints are very warm they become pliable and soft, and stretch much further than they would do normally. This is important in Astanga yoga because it prevents you from injuring yourself in postures that demand great flexibility. Sweating during yoga practice is purifying because it carries toxins out of your body. Heat purifies the mind and spirit as well as the physical body.
The theory of yoga teaches that human beings exist in a subtle as well as a physical form. The subtle body has its own distinct anatomy consisting of channels known as nadis and energy centres known as chakras. In the area of the navel is the digestive fire, known as Agni. Heat produced during yoga stokes Agni, with the result that "impurities," such as emotional blockages and mental patterns, are burnt away, allowing energy to flow freely around the body's subtle anatomy.
Bandha is the term that is used in yoga to refer to a muscular contraction or "lock." Bandhas produce particular effects on both the physical and the subtle bodies; they increase physical strength, develop muscular control, support your spine and have a quickening effect on the subtle energy. The powerful effect of the upward rise of subtle energy should not be underestimated; in many ways it is what makes this practice physically possible.
In Astanga yoga three bandhas are used during posture practice: mula, uddiyana and jalandhara bandhas. Mula and uddiyana bandha are held, to some degree, throughout the entire session. In many other schools of yoga, bandhas are practised only in association with breathing exercises, mudra (seals) and meditation - or by themselves.Bandhas can be contracted mildly or strongly, or anywhere in between. At first you may only be able to tell the difference between a bandha that is either fully engaged or not engaged. If your pelvic floor and low abdominal muscles are weak, for example, you may also find that you can only hold a contraction for a few seconds before your muscles just seem to "slip away." It takes time and practise to use the bandhas with great precision.
Another benefit of using the lower bandhas is that they indirectly increase your breathing capacity. During a normal inhalation, your diaphragm moves down from its arched resting position at the bottom of your ribcage and pushes out your abdomen. When your lower bandhas are engaged, your diaphragm can't descend in the usual way so your abdomen doesn't swell outward. Instead, your breath meets resistance and spreads upward and outward through your chest. This causes your lungs to inflate fully and expand the chest muscles (the intercostals) from the inside. This way of breathing is now commonly called "empowered thoracic breathing" and it produces a positive and focused mental state.
Tara Fraser is author of Total Astanga (Duncan Baird Publishers; 2005; $19.95; www.dbponline.co.uk) and is the founder and co-director of Yoga Junction in London. She believes yoga can help you to live well, feel good and age gracefully. She is author of Yoga for You, Live Better Yoga and Easy Yoga Workbook.