Asana and Yoga
Huge confusion persists in Yoga-world and its close environs. The main confusion has been making the term ‘yoga’ synonymous with ‘asana.’ Asana is part of yoga, but a fairly small part; traditionally about 2%. The West has reversed the emphasis.
Asana comes from the Sanskrit root -ās / sit. The sitting practices of dhyāna /meditation are the true core of yoga.
If you visit a Hindi speaking house, you will be invited to take an āsan, a seat. While the primary definition of -ās is sit, the secondary definition is apply oneself or be present as in abasya/ practice.
Hatha Yoga
The definition of asana as applied to the postures in Hatha Yoga is more a cultural idiom than a definition drawn from the root. This idiom refers to the macro postures and practices as preparatory for sitting. Properly understood, all Hatha Yoga, including asana, is preparatory for the dhyāna/meditation of Raja-Yoga and the first two verses of the Hatha Yoga Pradīpikā state that unequivocally.
A recent New York Times article alleging asana induced injury misses on two points: 1) properly understood, yoga-asana is NOT about fitness as understood in the West (however, all fitness activities produce injuries); the Sanskrit term for exercise is vyāyāma; such exercise may superficially look like asana, but is completely different, (2) a movement process that results in injury could not be yogic despite superficial similarities in appearance.
Hatha Yoga is NOT to be confused with circus contortion – I know this having taught asana in a circus college that had a contortionist. After the third session, she said, “This (asana) is totally different from what I do in the ring.”