The Science of Yoga

yoga dangers in the pages of the British Medical Journal , a mainstay of the field established in 1840, just as Paul was finishing medical school in Calcutta. He drew parallels between yoga and such recognized threats as the beauty-parlor syndrome, noting that some poses produce “extreme degrees of neck flexion and extension and rotation.” He specifically cited the Shoulder Stand and the Cobra, displaying a good understanding of the field. In the Cobra, or Bhujangasana, “serpent” in Sanskrit, a student lies facedown and slowly rises off the floor, pushing the trunk upward with the arms and extending the head and spine backward. Iyengar, in Light on Yoga , suggests that the head should arch “as far back as possible.” Photos show him doing just that, his head thrown back on a trajectory toward his buttocks—in other words, the kind of maneuver that Russell found worrisome.

    Cobra, Bhujangasana
    In the Shoulder Stand,the neck is bent in exactly the opposite direction, going far forward, with the chin deep in the chest, the trunk and head forming a right angle. “The body should be in one straight line,” Iyengar emphasized, “perpendicular to the floor.” Ever the enthusiast, he called the pose “one of the greatest boons conferred on humanity by our ancient sages.”
    Where Iyengar saw benefits, Russell saw danger. The postures, he said, “must for some people be hazardous.” His choice of the word “must” betrayed the speculative nature of his worry—but one grounded in a lifetime of experience. Russell warned that the basilar artery syndrome could strike practitioners of yoga and went on to cite a shadowy complication—doctors might have a hard time discerning its origin. The cerebral damage, he wrote, “may be delayed perhaps to appear during the night following, and this delay of some hours distracts attention from the earlier precipitating factor, especially when there is a catastrophic stroke.” In that case, of course, the deceased could give no account of prior activities.
    His caution went to the inherent difficulty of understanding the cause of invisible brain injuries. We typically think of illness as focused on a particular body part—such as the heart or lungs. But the origins of strokes often lie relatively far away from where they hit, starting in the wilds of the bloodstream and ending in the brain. The gap, moreover, could involve not only distance but time—hours and sometimes days—as a clot worked its way downstream or as a damaged artery slowly became swollen and gradually reduced the flow of blood. Such complicating factors meant that, for a large percentage of strokes, physicians could discover no obvious explanation. Their medical term for such injuries was cryptogenic, meaning their origin remained a mystery.
    That kind of uncertainty had long obscured the cause and the extent of the beauty-parlor syndrome. In essence, Russell was now asking if the same thing was happening with yoga.
    His alert proved timely. Perhaps he was simply ahead of his day, or perhaps his warning opened the eyes of colleagues, or perhaps the growth of yoga was resulting in more injuries. For whatever reason or reasons, an American physician in the following year, 1973, made public a gruesome case study. The author was Willibald Nagler. He worked on Manhattan’s Upper East Side atthe Weill Medical College of Cornell University. A world authority on spinal rehabilitation, he had counted President Kennedy among his patients.
    In his report, Nagler described how a woman of twenty-eight, “a Yoga enthusiast” as he called her in the sketchy anonymity of clinical reports, had suffered a stroke while doing a position known in gymnastics as the Bridge and in yoga as the Wheel or Upward Bow (in Sanskrit Urdhva Dhanurasana). The posture begins with the practitioner lying on his or her back and then pushing up, balancing on the hands and feet and lifting the body into a semicircular arc. An intermediate stage can involve raising the trunk and resting the crown of the head on the floor.

    Wheel or Upward Bow, Urdhva Dhanurasana
    Nagler reported that the woman entered her crisis while balanced on her head, her neck bent far backward. While so extended, she “suddenly felt a severe throbbing headache,” he reported. She had difficulty getting up. After she was helped into a standing position, she was unable to walk without assistance.
    The woman was rushed to the hospital and found to be