The Science of Yoga

the medical terms and laid out the health benefits, giving his book a feeling of scientific authority while avoiding the messy issue of evidence. It was light with no explanation of its origin.
    More aggressively, Iyengar claimed a wide array of cures and therapeutic benefits, again with no reference to supporting evidence other than “experiences with my pupils.” His book used the word “cure” dozens of times. At the book’s end, he laid out a master list of “Curative Asanas” for nearly one hundred ailments and diseases. They included arthritis, asthma, back pain, bronchitis, diabetes, dysentery, epilepsy, heart disease, insomnia, migraine headaches, polio, pneumonia, sciatica, sterility, tonsillitis, ulcers, and varicose veins.
    The subliminal message was perhaps the most important of all. Nearly six hundred photographs showed Iyengar bending his supple body into all kinds of loops and curls, twists and knots. Here was an accomplished body builder whose appearance bore no hint of yoga’s past. He displayed no ashes or amulets, no matted hair or beard. Ages of decay had given way to a new kind of yogi.
    The agenda no longer featured sex. Even so, it still made a few appearances, often with a therapeutic spin. For instance, Iyengar put impotence on his list of curable ailments.
    More important, at the very end of his book—in the final pages of a section called “Hints and Cautions,” buried in a discussion of advanced practices, couched in language more evocative than explicit—he made a sudden disclosure. Even sanitizedyoga, it turned out, retained a considerable measure of its old fire.
    Iyengar spoke of “sexual retentive power” and suggested that the discipline could fan the smoldering embers of human sexuality into a tempestuous blaze. If the yogi gave in, he said, “dormant desires are aroused and become lethal.”
    It was like a doctor suddenly informing a patient that the current course of treatment had serious, previously undisclosed side effects. And it got worse. Iyengar proceeded to spell out the ultimate stakes, making his belated admission in the middle of a very large paragraph. In my edition, the disclosure comes on page 438.
    Yoga, Iyengar warned, could transport the practitioner “to the cross-roads of his destiny.” One path led to the divine, he said, and the other to “the enjoyment of worldly pleasures.”
    In its fundamentals, the transformation of yoga was now complete. It had gone from the calling of supermen to the pursuit of common men—and increasingly of common women. It no longer belonged to mystic loners but to humanity. Its home was no longer India but the world. Its mode of instruction was public rather than private. To a growing degree, its practitioners no longer reveled in skulls and ashes but exercise mats and gym clothes. Enthusiasts by the millions ignored the old mysticism for the new ambitions of health and fitness. If yoga still harbored some of its old eroticism, that aspect of the discipline typically got ignored and downplayed, often to the point of invisibility.
    In short, yoga had gone from an ancient obsession with transcendence of the body to a modern crusade for a new kind of physicality.
    Of the ironies that come to light in a review of yoga’s modernization, one of the greatest is how its health agenda—begun by Paul, seized on by Hindu nationalists, developed as an export item, marketed with bold pretense, championed globally as the ultimate life enhancer—turned out to produce a wealth of real benefits. The posturing in some respects proved to be fortuitously accurate. The evidence grows richer every few days, as suggested by PubMed’s posting of new reports on yoga at the rate of more than one hundred a year.
    A large body of research derives from the kinds of metabolic slowdowns that Paul beganto identify a century and a half ago. For instance, scientists have found that physiological slowing from yoga can reduce stress, the heart rate, and blood pressure, helping to boost immunity and prevent diseases. In 2009, investigators at the University of Pennsylvania reported that twenty-six people who did Iyengar yoga for three months succeeded in reducing hypertension and its precursors. That is important because hypertension, or high blood pressure, is associated with an increased risk of stroke, cardiovascular disease, and kidney disease. Strange as it seems, the deathlike trance of the Punjab yogi ultimately threw light on healthy