For a very long while, Ashtanga Yoga origins have been linked to the Ashtanga practice invented by Patanjali. The current version of Ashtanga yoga description by K. Pattabhi Jois emphasizes an energetic approach to the postures (asana) and the breath control (pranayama), those being the traditional components of Ashtanga yoga. In order not to confuse Ashtanga Vinyasa yoga with classical Ashtanga yoga, some call the system of K. Pattabhi Jois "power yoga", or, in Sanskrit, Ashtanga Vinyasa yoga. It is often associated by its practitioners with a harsh sweat odor. From this you can imagine its hardness.
The central part of Ashtanga Vinyasa yoga practice contains six difficult series of postures, where each posture requires from ninety minutes to three hours to fulfill.
The organization of Ashtanga Vinyasa yoga makes you go over and over again through a whole continuum of postures, many of which are unpleasant, and most of them seem very difficult or practically unreachable to the new practitioners. The succession works like a combination. Only if you complete the right postures in the precise order, will your mind and your body be opened up automatically.
Every cycle unlocks a certain aspect of your body and your mind. The most important succession, which is called chikitsa yoga (therapeutical yoga), rearranges and detoxifies your physical body, principally the spinal muscles and the spinal column. Chikitsa yoga also creates the basis of significant physical strength, which is especially important as a method to balance the extraordinarily flexible practitioners who often go in for Hatha yoga. The transitional complex, called in Sanskrit nadi shodana (purification of the so-called "nadi" - "rivers", or channels), cleans the nervous system, makes it considerably stronger and purifies the delicate channels of energy that connect the seven chakras.
The four highly developed series in the beginning were taught as two, but later those two series were subdivided in order to make them a little bit easier physically and more accessible for the Ashtanga Vinyasa yoga practitioners. Those series are altogether known as sthira bhaga (Sanskrit: "divine stability"). These sophisticated successions raise you to the new heights of strength, agility, flexibility, focus and energy management, which are developed in the previous two series.
A typical Ashtanga Vinyasa yoga class begins with a prayer in Sanskrit. When the chants die away, the master will remind the practitioners to arrange the three core techniques of the Ashtanga Vinyasa yoga: ujjayi (a specially performed breathing), mula bandha practice, and a variant of so-called uddiyana bandha.
One of the factual dangers in Ashtanga Vinyasa yoga is that the practitioners may attempt to overdo the required exercises and thus somehow get injured in that process. The postures are quite challenging and they have to be performed in strict succession; one posture is subtly changed by the other.