The history of Yoga (which is often translated as union) goes off way into antiquity. The first written references on the subject are the so called yoga sutras (sutra literally meaning thread) written about 200 B.C by the sage Patanjali but he was documenting and to a certain extent organising, what was already a common practice. Patanjali speaks at some length on the so called eight limbs (meaning aspects) of yoga. The first is Yama which a sort of Indian seven commandments (although there are only 5 of them) or set of universal ethics. You are not to lie, steal, be greedy or violent and there is also a yama called brahmacharya which could (and has) be translated as chastity but is more likely to mean remaining pure of heart. The second limb of yoga is Niyama which is a more personal set of ethics involving diligence, cleanliness, and attempting to be a bit more spiritual. The third limb of yoga is practicing asanas which are the various postures seen in yoga which help strengthen mind and body. The forth limb is pranayama which is all to do with breath control. The rest of the eight limbs are pratyahara, dharana, dhyana and samadhi with samadhi being the ultimate goal, a sort of ecstatic meditative state and the others leading up to it. From this it will be seen that turning up at the gym twice a week to keep your buttocks in trim is not really what yoga was originally supposed to be about. That said, it is what a lot of people use it for and various forms of yoga have been developed over the centenaries for various requirements.
Hatha yoga is probably the most popular in the west. The word is derived from two roots, ha meaning sun and th meaning moon. It is possibly the most versatile as it can be used simply to keep fit but can lead on to more spiritual layers later. Amongst the asanas in hatha yoga are a set of 12 entitled ‘salutation to the sun’ which was traditionally performed at dawn. There are also some specific yoga breathing exercises such as the lion breath which involves breathing out loudly with your tongue sticking out and is, I have found, extremely difficult to perform without bursting into fits of giggles. Vini yoga is another good ‘all rounder’. Somewhat less strenuous than hatha yoga it is normally taught individually rather than in a group and can be ideal for the elderly or particularly unfit. At the other end of the spectrum is the recent addition to the yoga family, power yoga. This is ridiculously energetic, doesn’t give a fig about breathing techniques or spirituality and no normal person could keep it up for more than a few seconds without dying of exhaustion, (perhaps I am exaggerating a little). Proponents of this system include Sting, Madonna and people in spandex leotards who would think nothing of sprinting a marathon before breakfast. For a more spiritual approach Raja (royal) yoga is a good bet containing as it does a fair amount of meditation and breathing exercises and since the publication of ‘autobiography of a yogi’ kriya yoga has gained immense popularity. Also a spiritual tradition, containing elements of tantra but without the sex, personally I prefer the sound of raja yoga as kriya yoga is full of secrets and initiations and seems to cost a lot more.
Whatever form of yoga you go for it is obviously important to warm up properly and warm back down when you have finished. Normally nothing more sophisticated than a padded mat is required, except in Iyengar yoga which makes use of bits of rope and plastic blocks to help you maintain the asanas. It is important to find a class at your own level. A beginner in a class full of people standing on their heads in the full lotus position will at best feel somewhat sheepish and at worst do themselves a mischief attempting asanas that are way beyond there present abilities. Yoga is not competitive in any way and you will derive far more benefit from simple asanas done properly than difficult ones done badly. It is also best to avoid classes that are so large that the instructor can not keep an eye on everyone at once as incorrectly performed yoga (in common with any incorrectly performed form of exercise) is far more likely to result in injury. Lessons are likely to last between an hour and an hour and a half but to get the most from yoga it would be necessary to practice almost every day, although not necessarily for as long as ninety minutes