The Science of Yoga

The Science of Yoga

The Science of Yoga

Below is a book review from Laura A. Garren.  Hope you enjoy!

A Review of The Science of Yoga: The Risks and The Rewards, by William J. Broad

By Laura Garren

Anyone who practices yoga, or is thinking of starting, should read The Science of Yoga: The Risks and The Rewards, by William J. Broad (2012). It’s scrupulously documented, well written, interesting, and informative. Above all, it’s fair.

The book is not an attack on yoga. The author, who is a prize-winning, senior writer at The New York Times and has practiced yoga since 1970, offers clarification and information about this ancient spiritual and physical practice. Many claims have been made about yoga throughout its history—including that can bring immortality—and Broad’s purpose is to separate fact from fabrication.

Some of Broad’s findings run counter to claims frequently made by yoga practitioners, including that practicing traditional yoga (as opposed to recently invented forms) increases the metabolism. According to many scientific research studies, it does not; in fact, practicing yoga lowers the metabolism. So why aren’t all yoga practitioners fat? Possibly, because the practice works on not only the physical level, but also the emotional and mental levels, producing a calmness that reduces cravings.

Another misconception about yoga is that it increases cardiovascular fitness. Again, clinical studies show that yoga has a negligible effect in this regard. But so what? You can get those benefits elsewhere, for instance by taking a brisk walk several times a week for a half an hour. Yoga does lower blood pressure, blood sugar, cholesterol, and a protein involved in blood clotting; raise the levels of antioxidants in the bloodstream; counteract spinal disc deterioration; tone the muscles; increase strength, flexibility and balance; and increase levels of telomerase, an indictor of cell health and longevity, giving weight to the claim that yoga can extend the life span.

The most startlingly misconception of yoga concerns the claim that the slow breathing associated with yoga pulls oxygen into the body. Instead, what happens with slow breathing is that the exhalation of carbon dioxide is limited, causing it to pour into the bloodstream. In response, the cerebral blood vessels dilate, which means more oxygen gets to the brain, producing a calming effect. (While this explanation may sound nitpicking, it seems important to make accurate claims in order to be considered credible, especially if you are a yoga practitioner.) The process differs with fast breathing: fresh air, with low concentrations of carbon dioxide, is taken in quickly, lowering the inner levels of this gas. “Nature seeks to equalize the concentrations,” explains Broad, “so diffusion quickly draws more carbon dioxide out of the bloodstream and into the lungs. The result is that the body’s levels plunge.” Another name for this phenomenon is hyperventilation, which can cause blackouts, dizziness, feelings of lightheadedness, and tingling in the lips or extremities.

So what are the risks of yoga? (I can just hear legions of yoga instructors bristling at the implication that yoga can hurt you.) The fact is that practicing yoga can result in injuries, sometimes severe. The good news is injuries typically are a result of stupidity, ignorance or egotism on the part of the practitioner: for example, the woman who falls asleep in a seated forward fold and suffers crippling and irreparable damage to her sciatic nerve; or the folks who attempt shoulder stands but stay in the pose either too long or hold it incorrectly, which can and have caused strokes; or the woman who shows off a pose before she’s warmed up, causing a ruptured hamstring and months of pain and physical therapy.

Injuries also have been caused by irresponsible instructors who push students too far or by under-qualified instructors who don’t know what they are doing. Frighteningly, the process of becoming an instructor is not regulated. Some institutions grant the status of yoga instructor after a long weekend of study or through educational videos, but with no oversight by veteran instructors and no hands’-on work. Basically, anyone can say he or she is a yoga instructor. Broad urges anyone interested in starting yoga to find out how and where an instructor has been trained.

Broad also offers a brief but comprehensive history of yoga and its most influential (and in some cases, infamous) practitioners and a look at the different forms of yoga and yoga poses. He also illuminates the often-misunderstood kundalini yoga and calls for more regulation around yoga instruction. Finally, he extols the ineffable effect that yoga has; that which can never be explained, only experienced. Mystery remains, even after Broad sheds light on the truths and myths surrounding this


Elizabeth Delaney