The Science of Yoga

to be surprisingly common. In his Pennsylvania class, we practiced a number of precautions, especially on how to unburden the neck in the Headstand and Shoulder Stand.
    As a group, theactivists tend to be in closer alignment with the findings of science than yoga traditionalists. Just as Robin and his Iyengar colleagues have redesigned the Headstand, some of the reformers have focused on reinventing some of the most dangerous poses or advising students to drop them altogether.
    Such reevaluations may go against yoga’s timeless image. But as we have seen, yoga has proved itself quite flexible in adapting to the needs and desires of different ages. Today, the long silence of the gurus has given way to scientific inquiries that are nurturing new strategies for injury prevention. The reform movement is a happy case study in what can happen if yoga and science cooperate, even grudgingly. The inconspicuous wave of reinvention promises to benefit millions of students around the globe and, not insignificantly, to help modern yoga live up to its good reputation.
    In my travels, I learned of an experienced yogi who was said to know the inside story on yoga injury. Prominent gurus had supposedly come to him for help in rehabilitation and recovery. One client was reported to have received a hip replacement before reentering the celebrity life. I decided to track him down.
    Glenn Black had traveled to India, studied at Iyengar’s school in Pune, and, like the ancient yogis, spent years in solitude. He ran yoga intensives in the jungles of Costa Rica. In New York City, for a decade, he studied with Shmuel Tatz, a Lithuanian who devised a unique method of physical therapy that he dispensed from offices above Carnegie Hall to actors, singers, dancers, musicians, composers, and television stars. Black had settled down in Rhinebeck, New York, on the Hudson River. Honored as a master teacher and anatomist, he often taught yoga at the nearby Omega Institute, a New Age emporium. Black had a devoted following drawn to his earthy, no-nonsense style. He also had an elite bodywork clientele that included celebrities. Of late, he was said to have narrowed his client list down to a handful of billionaires.
    One day I noticed that Black was scheduled to teach a master class in Manhattan. I hesitated but was told that resolve was more important than skill. I arranged to talk with him afterward.
    On a cold Saturday in early 2009, I made my way to Sankalpah (aim, will, determination) Yoga, a third-floor walkup on Fifth Avenue between Twenty-Eighth and Twenty-Ninth. The room was filled with lean bodies, roughly half of the individuals said to be teachers.
    The class was brutal. Black joked, walked around a lot, talked constantly, played jazz on the sound system, watched us like a hawk, and cajoled relentlessly. Beads of sweat turned into rivulets. He was highly demanding yet surprisingly gentle, having us do lots of stretching, limb movements, and pose holding but no inversions and few classical postures. His teaching was nothing like the regimented styles. Instead, he worked us from the inside out. His approach was almost freeform and it seemed as if he was making it up as he went along, switching gears every so often to better challenge the range of aptitudes in the room or to pull us back from what he perceived to be some kind of cliff. In so doing, he conveyed a sense of intelligent vitality.
    Through it all, he urged us to concentrate and try to develop our sense of attention and awareness, especially to the risky thresholds of pain. “I make it as hard as possible,” he told us. “It’s up to you to make it easy on yourself.”
    Playfully, he rejected any doubts about his style. “Is this yoga?” he asked as we sweated through an extremely unyogalike pose. “It is if you’re paying attention.”
    Black told us a grim story. In India, he said, a yogi from abroad had come to study at Iyengar’s school and threw himself into a spinal twist. Black said he watched in astonishment as three of the man’s ribs gave way— pop, pop, pop.
    After class, I joined Black and his companion, Evelyn Weber, on a cab ride back to their hotel. They said they were both born in 1949 and were turning sixty. Both looked much younger. “I am certified in nothing,” Black remarked at one point. “I have no degrees. All I have is a ton of experience.”
    Discreet and luxurious, Hotel Plaza Athénée was located on the tree-lined Upper East Side at 64th