The Science of Yoga

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 requires at least 500 hours—equal to about three months.
    Compare that to Iyengar. It requires candidates for teacher training to have studied the style for a minimum of three years, and then trains them for a minimum of two years and administers two examinations to ensure the requisite progress. As we have seen, it is the Iyengar people who have redesigned some of yoga’s most dangerous poses. Teacher training puts much emphasis on how to lessen the risks.
    My reporting on yoga injury kept producing surprises, none bigger than those involving Glenn Black. In late 2009, almost a year after meeting him, I received an email. Black said he had undergone spinal surgery. “It was a success,” he wrote. “Recovery is slow and painful. Call if you like.”
    I caught up with him at Plaza Athénée. He said the surgery had taken five hours, fusing together lumbar vertebrae three, four, and five. He would eventually be fine but was under surgeon’s orders to take it easy with his lower back.His range of motion, he added, would never be quite the same.
    He had done it to himself, Black insisted. The injury had nothing to do with trauma or aging but instead had its origins in four decades of extreme backbends and twists. To me, that recalled the wear and tear injuries of the elder yogi whose Headstands led to limb tingling, as well as Timothy McCall and his arm troubles.
    In Black’s case, it appeared that long practice had resulted in spinal stenosis—a serious condition in which the openings between vertebrae begin to narrow, compressing spinal nerves and causing severe pain. Black said he felt the tenderness start twenty years ago when he was coming out of such poses as the Plow and the Shoulder Stand. By 2007, the pain had become extreme. One surgeon said he would eventually be unable to walk. So the master teacher—a man who had been quick to speak of yoga’s dangers and to put down instructors who underwent stealthy rounds of reconstructive surgery—prepared to go under the knife.
    Black said he became quite moody as the date approached. “It was incredible,” he said. “There was a lot of turmoil.”
    I asked if the problem couldn’t have been congenital or the result of aging. No, he argued. Black said he was sure he had done it to himself.
    After recovery? “I’m going to be a decrepit old man,” he joked.
    The moral?
    “You have to set aside your ego and not become obsessive,” he replied, instantly serious. “You have to get a different perspective to see if what you’re doing is going to eventually be bad for you.”
    Black said he had recently taken that message to a conference at the Omega Institute, his feelings on the subject deepened because of the surgery. But his warnings—articulated with new vigor—seemed to fall on deaf ears. “I was a little more emphatic than usual,” he said. “My message was that ‘Asana is not a panacea or a