The Science of Yoga

be able to do this by now.’ It has to do with their egos.”
    Black also chided students who practiced yoga for the excitements of status and cachet. “They take a class to show off their Missoni T-shirt or their leotards,” he said, scowling. I asked his opinion of Yoga Journal, which over the decades had gone from a geeky nonprofit published by the California Yoga Teachers Association to a glossy magazine filled with ads for sexy clothing, travel adventures, and miracle weight-loss drugs. He declined comment.
    While many gurus and yogis over the decades had remained silent on the threat of injury, or had denied its existence, or had grudgingly made limited concessions of danger, Black insisted that the threat was now indigenous to the discipline and just waiting to strike. He argued that a number of factors had come together in modern times to heighten the risk.
    The biggest was the changing nature of students. The poor Indians of yoga’s past normally squatted and sat cross-legged, the poses thus being in some respects an outgrowth of their daily lives. Now yoga had become a Western fad, swelling its unskilled ranks. Urbanites who sat in chairs all day now wanted to be weekend warriors despite their inflexibility and physical problems. Amateurish teachers ruled like drill sergeants and pushed cookie-cutter agendas. Such factors became all the more deadly, Black argued, with the distractions of modern vanity, which kept students and teachers from focusing on the importance of the here and the now, from listening to their bodies and understanding when they were about to cross the line from a wholesome stretch to excruciating harm.
    The result was an epidemic.
    “There has to be a degree of seriousness and dedication,” he said. “Otherwise, you’re going to get hurt.”
    The first scientific light on the topic of yoga injury fell decades ago. The reports appeared in some of the world’s most respected journals—including Neurology, the British Medical Journal, and The Journal of the American Medical Association. The high-level debut signaled that the medical establishment saw the findings as important information that practicing doctors needed to know if they were going to help patients. The reports began toemerge in the late 1960s, soon after the West had become newly interested in yoga.
    A number of early findings centered on nerve damage. The problems ranged from the relatively mild to permanent disabilities that left students unable to walk without aid. For instance, a male college student had done yoga for more than a year when he intensified his practice by sitting upright for long periods on his heels in a kneeling position known as Vajrasana. In Sankrit, vajra means “thunderbolt.” The position, also called the kneeling pose, is sometimes recommended for meditation. The young man did the pose for hours a day, usually while chanting for world peace. Soon he was experiencing difficulty walking, running, and climbing stairs.

    Thunderbolt, Vajrasana
    In Manhattan, an examination showed that both of his feet drooped because of a lack of leg control, and doctors traced the problem to an unresponsive nerve. It was a peripheral branch of the sciatic, the longest nerve of the body, which runs from the lower spine, through the buttocks, and down the legs. The damaged branch ran below the knee, normally providing the lower leg, foot, and toes with sensation and movement. Apparently, the young man’s kneeling in Vajrasana had clamped his knees tight enough and long enough to cut the flow of blood to the lower leg,depriving the nerve of oxygen. The result was nerve deadening.
    It was suggested that the young man simply give up the pose. Reluctantly he did so, opting instead to do his chanting while standing. He improved rapidly, and a checkup two months after the initial visit showed no lingering problems. In describing the case, the attending physician called the condition “yoga foot drop.” The name stuck. In time, a number of similar cases emerged.
    One of the worst featured a woman of forty-two. She fell asleep in Paschimottanasana—the Seated Forward Bend, its Sanskrit name meaning “stretch of the West.” Upon awaking, she found her legs numb and weak. A medical team at the University of Washington, writing in The Neurologist, told of finding injuries to both her sciatic nerves that had crippled her legs. The scientists reported that the woman regained “some sensation” after three months