Award-winning journalist William J. Broad debunks many of the usual claims about yoga including the idea that yoga helps people lose weight. He reports on a study showing that "regular yoga practice cut the basal metabolic rate by an average of 13 percent." He adds, "In other words, individuals who took up the discipline would reduce their basal metabolic rate to such an extent that they required less food and fewer calories--or would add pounds if they ate and exercised in the customary manner." (pp. 96-97)
Broad also cites studies proving that "fast or slow breathing does little to change the levels" of oxygen "that enter the bloodstream." "The body's consumption of oxygen" increases "in response to changes of muscle activity, metabolism, and heart rate--not breathing styles." (p. 85) (By the way, peak oxygenation of the body--VO2 max--as Broad points out on pages 52 and 53, is the result of a big, strong heart and has nothing to do with breathing techniques).
Furthermore what helps yogis to go into trance or meditation through the practice of pranayama is the increased level of carbon dioxide in the system (not more oxygen). Paradoxically, fast breathing (e. g., Bhastrika or "bellows breath") decreases the amount of oxygen in the lungs relative to the amount of CO2! I was surprised to learn this. Broad notes, "the surge in carbon dioxide causes the blood vessels in the brain to contract, reducing the flow of oxygen and producing light headedness..." (p. 86)
Earlier in the book Broad notes that "yogis manipulate their breathing to discharge less "carbon dioxide" by taking fewer breaths. (p. 21) (This is a technique that I sometimes use to facilitate meditation.) Higher levels of carbon dioxide in the system can lead to euphoria, as can the repetition of "Om" or the recitation of mantras which slow the expiration of CO2. Concentration on euphoria leads to samadhi.
Perhaps the main value of this book is to point to the hitherto under reported physical risks that can come from the practice of asana. Broad himself was injured. He writes that he was coming out of the Extended Side Angle pose (Utthita Parsvakonasana) "chatting with my partner--instead of paying attention to what I was doing--when my back gave way." He adds, "Blinding pain forced me to ignore everything but the explosion of fire. It was excruciating. My legs failed and the room vanished in tears. My body slammed into a wall." His recovery took weeks. (p. 131)
In my book "Yoga: Sacred and Profane (Beyond Hatha Yoga)" I warn the reader repeatedly that it is essential that when doing asana to concentrate on the pose and nothing else otherwise the chance that you will pull or strain a muscle is very real. Furthermore, contrary to practices found in some yogic establishments you should never strain to achieve a pose and especially you should never hold the pose any longer than is comfortable. Much of the kind of yoga that Broad encountered featured straining and even a "no pain, no gain" sort of practice. This is entirely contrary to the spirit of yoga and accounts for the many injuries, some very serious, that Broad reports on.
Another thing contrary to the spirit of yoga is doing yoga in public! Broad notes that according to one student, "the mirrored walls of Bikram studios encouraged students to neglect the inner focus of yoga for outer distractions and pressures of a room full of competitive individuals...." (p. 124) Traditionally yoga has been said to be a "secret" practice. I discovered some years ago that what was really meant by the translated word "secret" was "private." Showing off or trying to go one up on another is entirely contrary to success in yoga. Of course what we have in commercial yoga establishments is social yoga. This is to the good in the sense that people need to be social and are encouraged in their practice by being in the presence of others. However after some time it will be realized that the union with ineffable that is the goal of yoga comes from doing yoga alone.
Mention of injuries and the malpractice of yoga brings up the subject of the accreditation of yoga teachers. Broad writes in the "Healing" chapter about the fuzziness of "RYT" which means "Registered Yoga Therapist" or "Registered Yoga Teacher." In either case, Broad writes, "The field is, on the whole, completely unlicensed and unregulated." (p. 150)
Now I want to get to some quibbles with what I think is otherwise an outstanding book.
While Broad briefly mentions the yoga sutras of Patanjali from two thousand years ago, which form the basis of Ashtanga yoga, he fails to mention the yamas and niyamas which are essential to success in yoga. But we'll say that's okay since Broad's focus is on the purely physical aspects of yoga. He more often refers to the "Hatha Yoga Pradipika" (from the fourteenth century CE) and the "Gheranda Samhita" (seventeenth or eighteenth century CE) since these are primarily works of hatha yoga. Broad notes that they are filled with the most fantastic claims and exaggerations for yoga such as destroying all disease, annihilate old age, etc. What Broad doesn't note is that such claims (1) fulfill a placebo-like purpose for the student so that his practice is enhanced and accelerated (if he believes), and (2) while one is in the state of samadhi, all pain and disease really are annihilated!
Broad does not mention the "Bhagavad Gita" in which the four orthodox yogas of India, bhakti, karma, jnana and hatha/raja, presented. He does spend some time on tantra, the so-called yoga of the left-handed path which is not mentioned in the Gita. And he writes all too much I believe on kundalini yoga which really isn't a yoga at all but an elaborate means to meditation.
Finally I want to note that "hot yoga" and various fast and very vigorous yogic styles which employ an extended "salutation to the sun" are really yogic-like exercise programs, calisthenics, if you will, not yoga.
While this book is controversial and probably offensive to some members of the yogic world, it is nonetheless an important book and a welcome addition to the literature of yoga. It is probably the best book ever written that explores yoga from a scientific point of view.
--Dennis Littrell, author of "Yoga: Sacred and Profane (Beyond Hatha Yoga)"