“[O 1] He gives as an example the evidence that yoga helps to relieve low back pain, but that with “a lack of quality studies [by 2013] comparing yoga to other forms of exercise”,[O
1] it is possible that yoga’s benefits are just what any form of exercise would provide, generically.
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.
 As therapy Systematic review has found strong evidence for beneficial effects of yoga as an additional therapy on low back pain[P 4] and to some extent for psychological
conditions such as stress and depression,[P 2][P 3] but despite repeated attempts, little or no evidence for benefit for specific medical conditions.
 In 1937, the Yale physiologist Kavoor 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”, accompanied by a marked slowing of mental performance on tests such as mental sums,
recognising colours and solving simple puzzles.
 Scope Yoga as exercise is defined by Merriam-Webster as “a system of physical postures, breathing techniques, and sometimes meditation derived from [traditional] Yoga
but often practiced independently especially in Western cultures to promote physical and emotional well-being”.
Yoga is also used directly as therapy, especially for psychological conditions such as post-traumatic stress disorder, but the evidence for this remains weak.
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.
[d][P 6][P 7] Cardiovascular health A 2012 survey of yoga in Australia notes that there is “good evidence”[P 8][P 9] that both yoga on its own, and its associated healthy
lifestyle—often vegetarian, usually non-smoking, preferring organic food, drinking less or no alcohol—are beneficial for cardiovascular health, but that there was “little apparent uptake of yoga to address [existing] cardiovascular conditions
and risk factors”.
[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
 Broad notes the “myth” that yoga, and especially pranayama, increases the supply of oxygen to the body.
 Yoga involves both isotonic activity, the shortening of muscles under load, and (unlike many forms of exercise) also a substantial amount of isometric activity, holding
still under load, as in any asana which is held for a period.
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.
[P 10] Yoga sessions often end (and sometimes also begin) with a period of relaxation in corpse pose, Shavasana.
The picture is, Broad writes, confused by the “predatory behaviour” of commercial ventures intent upon promoting themselves; but is being clarified by the American
National Institutes of Health, which began funding scientific research into yoga in 1998, leading to reliable reports of studies of yoga’s effects on different conditions.
Reviewers have noted the need for more high-quality studies of yoga’s effects.
[O 3] The science journalist William Broad notes that yoga has “wide health benefits”, and defines the scope of the science of yoga as to “better understand what yoga
can do and better understand what yoga can be”.
 Physiological effects Fitness Yoga can be used as exercise to help maintain physical fitness.
Yoga has sometimes been marketed with pseudoscientific claims for specific benefits, when it may be no better than other forms of exercise in those cases;[O 1] and some claims
for its effects on particular organs, such as that forward bends eject toxins from the liver, are entirely unfounded.
 Early in the 20th century, two pioneers of yoga as exercise in India, Yogendra and Kuvalayananda, worked to make Haṭha yoga acceptable, seeking scientific evidence
for the health benefits of yoga postures (asanas) and yoga breathing (pranayama).
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
[P 2][P 3] Broad notes the “diffuse nature of the existing science” with pieces of the metaphorical jigsaw puzzle of scientific knowledge of what yoga actually achieves
held in many laboratories around the world.
[O 6] On the other hand, yoga, like any other physical activity, can result in injury; headstand (Sirsasana), shoulder stand (Sarvangasana), and lotus position (Padmasana)
are the asanas most often reported as causes of injury.
“[O 1] The practice of yoga for children is similarly lacking rigorous study.
[P 11][P 12] For example, study of trauma-sensitive yoga has been hampered by weak methodology.
[a] Denise Rankin-Box, editor of Complementary Therapies in Clinical Practice, one of several Elsevier journals that publish papers on the effects of yoga (among other
matters), offers the definition “research addressing the impact of yoga on health and wellbeing.
[‘1. The LiveScience website similarly states “Modern-day science confirms that the practice also has tangible physical benefits to overall health benefits”.[O 4]
2. ^ Measured at 3.3 ± 1.6 METs.[P 6]
3. ^ Larson-Meyer and Enette found a range of
2.9 (light exercise) to 7.4 (vigorous) METs. Curious about the wide range of METs in Surya Namaskar, repeated the study (Mody) which gave the highest value; using “transition jumps, and full pushups”, he obtained “agreement” with 6.4 METs.[P 6]
Asanas performed individually provide on average 2.2 ± 0.7 METs; pranayama types performed individually provide just 1.3 ± 0.3 METs; a combined class provided 2.9 ± 0.8 METs.[P 6]
1. ^ Alter 2004, pp. 81–100.
2. ^ Broad 2012, pp.
3. ^ Singleton 2010, p. 52.
4. ^ Paul 1882.
5. ^ Shearer 2020, p. 251.
6. ^ Yogendra 1928.
7. ^ Singleton 2010, pp. 116–117.
8. ^ Alter 2004, p. 31.
9. ^ Goldberg 2016, pp. 100–141.
10. ^ Jump up to:a b Broad 2012, pp. 83–85.
12. ^ “World Yoga Conference”. The Times of India. 30 November 1970.
13. ^ Broad 2012, p. 54.
14. ^ Jump up to:a b c Broad 2012, p. 217.
15. ^ Swanson 2019, pp. 6–7.
16. ^ Swanson 2019, pp. 42–173.
17. ^ Swanson 2019, pp.
18. ^ Jump up to:a b Broad 2012, p. 218.
19. ^ Broad 2012, p. 219.
20. ^ Swanson 2019, p. 12.
21. ^ Swanson 2019, p. 118.
22. ^ Powers 2008, pp. 25, 176.
23. ^ Swanson 2019, p. 63.
24. ^ Swanson 2019, p. 202.
25. ^ “Yoga: What
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26. ^ Jump up to:a b Coulter 2007, Chapter 1. Movement: Isotonic and Isometric Activity.
27. ^ Kaminoff & Matthews 2012.
28. ^ Long & Macivor 2009.
29. ^ Swanson 2019.
30. ^ Coulter
2007, Chapter 2. Breathing. How Breathing Affects Posture.
31. ^ Coulter 2007, Chapter 2. Breathing. How Breathing Affects The Autonomic Nervous System.
32. ^ Coulter 2007, Chapter 2. Breathing. 2:1 Breathing.
33. ^ Coulter 2007, Chapter 2.
Breathing. The Bellows Breath and Kapalabhati.
34. ^ Broad 2012, pp. 85–89.
35. ^ Coulter 2007, Chapter 10. Relaxation and Meditation. The Corpse Posture.
36. ^ Swanson 2019, p. 27.
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Photo credit: https://www.flickr.com/photos/gnuckx/5674704952/’]