The Science of Yoga

precautions. His list included muscle strains, overstretched ligaments, and cervical disk injuries. Strangely, he said nothing about strokes.
    Eventually yogis sought to map the world of injuries by means of practitioner surveys. The questionnaires promised a better overview than the statistical surveys of the American government and, in the hands of yoga professionals, a better foundation for posture refinement and reinvention. The investigators, as was the case with many reformers, usually had backgrounds that combined yoga and science.
    In 2008, yoga researchers in Europe published a survey about practitioners of Ashtanga—the fluid style from Krishnamacharya that Holly Millea had practiced. Their study limited itself to damage of the muscles and skeleton, involved practitioners only in Finland, and produced just one hundred and tenresponses. But the results were fairly dramatic. The majority of the responders—62 percent—said they had suffered at least one injury that had lasted longer than a month, and some reported multiple upsets. The injuries were mostly sprains and strains, as well as two dislocations.
    In 2009, a New York City team based at the Columbia College of Physicians and Surgeons published a far more ambitious survey of yoga teachers, therapists, and doctors around the globe. It was done in cooperation with the International Association of Yoga Therapists, the Yoga Alliance, and Yoga Spirit, an education group in Toronto. More than 1,300 people in thirty-four countries responded. The Columbia survey asked not only for personal experiences but also observations about yoga students and patients. It appeared in the International Journal of Yoga Therapy , ensuring its wide reading among yogis interested in healing.
    The participants reported practicing Hatha and its many offspring, including Vinyasa, Iyengar, Anusara, Ashtanga, and Kripalu. The survey’s central question—“What are the most serious injuries (disabling and/or of long duration) that you have seen?”—produced a number of revelations.
    The largest number of injuries (with 231 reports) centered on the lower back. In declining order of prevalence, the other main sites were the shoulder (219 incidents), the knee (174), and the neck (110).
    Amid these generalities came more specific accounts. The respondents said they knew of forty-three times that spinal disks had herniated, seventeen times that bones had fractured, and five times that practitioners had suffered heart problems.
    Then came stroke. Its debut in a yoga survey came nearly four decades after Russell’s warning. The respondents said they had witnessed four cases—in other words, they knew of four occasions in which yoga’s extreme bending and contortions had resulted in some degree of brain damage.
    For the community, the admission was a significant step. Few yoga books ever spoke of the danger—or looked into the medical literature—and the grim topic seldom made the upbeat pages of yoga magazines. Now, a major survey done by yoga professionals had documented the threat. It was an honest first.
    Another surprise centered onjudgments about what explained the injuries. The choices for survey takers included such factors as large classes, too much effort, and expanded ranks of students. A vast majority of the respondents—68 percent—pointed to “inadequate teacher training.” That was remarkable because most were teachers. In effect, they were criticizing themselves and their peers.
    The candor went to an inconspicuous deficiency of modern yoga —that teacher training varies enormously in quantity and quality, from slapdash to rigorous. You can get certified as an instructor with as little as 100 hours of training and even do the course entirely online, putting in no time whatsoever in a classroom and getting no supervision from an experienced teacher.
    Today many popular styles adhere to the minimum standards set by the Yoga Alliance, a private group in Arlington, Virginia, that seeks to build public confidence in yoga. Its definition of a yoga teacher is anyone who has participated in at least 200 hours of real training. Still, that effort—equal to four or five weeks—seems like an extraordinarily low bar in terms of serious education. Would you study with violin teacher who had trained for a month? A sculptor? A basketball player?
    Bikram is more demanding. It trains its instructors for nine weeks. Yoga Alliance also endorses a category of training that