Science of yoga
Yoga's effects are to some extent shared with other forms of exercise,[O 1] though it differs in the amount of stretching involved, and because of its frequent use of long holds and relaxation, in its ability to reduce stress.
It improves posture, muscle strength, coordination, and confidence, in turn reducing the risk of injury and bone fracture.
As it is generally slow and conducted with awareness, it may be safer than many other sports; but some postures such as headstand, shoulderstand, and lotus position have been reported as causes of injury.
[7] In 1924, Kuvalayananda founded the Kaivalyadhama Health and Yoga Research Centre, combining asanas with gymnastics, and like Yogendra seeking a scientific and medical basis for yogic practices.
[8][9] In 1937, the Yale physiologist K. T. Behanan published his book Yoga: A Scientific Evaluation, reporting that a form of pranayama, Ujjayi ("Victorious breath"), performed at the slow rate of 28 breaths in 22 minutes, could create a deeply relaxed state that he called "an extremely pleasant feeling of quietude",[10] accompanied by a marked slowing of mental performance on tests such as mental sums, recognising colours and solving simple puzzles.
The science journalist William Broad notes that this finding contradicted the image of yoga as conferring special powers.
[P 2][P 3] Broad notes the "diffuse nature of the existing science"[14] with pieces of the metaphorical jigsaw puzzle of scientific knowledge of what yoga actually achieves held in many laboratories around the world.
[P 5] Ann Swanson offers three reasons why yoga may be safer than many sports, namely that it is often slow; it encourages awareness in the moment; and it stresses doing no harm (ahimsa).
He writes that instead, fast vigorous breathing as with bhastrika may indeed feel exhilarating, as B. K. S. Iyengar reported, but it lowers the level of carbon dioxide in the blood.
[35] There is strong scientific evidence that yoga is a safe and effective additional therapy for people with low back pain.
Much of the research on the therapeutic use of yoga, including for depression, has been in the form of preliminary studies or clinical trials of low methodological quality, suffering from small sample sizes, inadequate control and blinding, lack of randomization, and high risk of bias.
[O 1] Novella points out that yoga also has a spiritual side, so claims made for it can mix science with "a liberal dose of pure pseudoscience and mysticism.
