The Science of Yoga

strength, and subtle awareness to proceed safely.”
    On another occasion, Kaitlin Quistgaard, the editor of Yoga Journal , told of how she had reinjured a torn rotator cuff in a yoga class, her pain becoming a cruel presence for months. “I’ve experienced how yoga can heal,” she wrote. “But I’ve also experienced how yoga can hurt—and I’ve heard the same from plenty of other yogis.”
    And, no doubt, from plenty of lawyers. In fine print, the magazine began to run a legal proviso: “The creators, producers, participants, and distributors of Yoga Journal disclaim any liability for loss or injury in connection with the exercises shown or the instruction and advice expressed herein.”
    To its credit, themagazine paid attention to strokes, although it did so somewhat defensively and superficially. “Proceed with Caution,” read the headline of its one-page article. The large color photo showed students upended in Headstands. The neck of a woman in the foreground was backlit and stood out. The article said doctors had identified five risky poses: the Headstand, the Shoulder Stand, the Side Angle pose (which Krishnamacharya had hailed as a cure), the Triangle (which Iyengar had carefully aligned), and the Plow, or Halasana. It had students lie on their backs, lift their legs up over their heads and back down onto the floor, inverting the torso. The article said such poses were judged potentially dangerous because they “put extreme pressure on the neck” or resulted in “sudden neck movements.”

    Plow, Halasana
    It said nothing of two other poses that physicians had identified as serious threats to the brain: the Cobra and the Wheel, both considered X-rated postures.
    The article warned thatyoga practitioners could mistake injuries of the vertebral arteries for simple migraines or muscle tension. The symptoms of deeper trouble, it said, included piercing neck pain, pounding one-sided headaches, and facial paralysis. “Warning signs,” it cautioned, “can intensify for hours or even days before a stroke hits.”
    So far, so good. But the magazine then proceeded to downplay the threat by failing to put the issue in perspective. It said doctors had found injuries to the vertebral arteries from all causes (such as yoga, beauty salons, and chiropractors) to be rare—annually, a person and a half out of every hundred thousand.
    This was accurate. But it ignored the big picture. If twenty million people in the United States did yoga—a standard figure—and if yogis suffered the injury at the same rate as the general population (a very cautious assumption, given all the neck twisting and bending), that meant three hundred yogis in the United States faced the threat of stroke each year, or three thousand over a decade. The magazine not only neglected that baseline figure but sought to put its readers at ease by stating that yoga was “the culprit in a minuscule number of cases.”
    The reassurance was empty because the medical world had exactly zero evidence about the frequency of such damage. In fact, no scientist had ever published a study on how often yogis injured their vertebral arteries. The question was far too esoteric to have received the kind of major funding that would be required to address a deep riddle of epidemiology. So the exact size of the problem with yogis in the United States was simply unknown. What was easy to estimate was its minimal extent—roughly three hundred yogis a year.
    Seeking to further brighten the grim subject, the magazine said “treatment is simple” and called rates of recovery high. But that rosy prognosis required that it ignore the agonizing months and years of therapy, the hand tremors and the clumsy gaits, the patients whose arms continued to waver and eyelids continued to droop.
    Then, in what was apparently meant to be more good news, it added: “Death results in less than 5 percent of the cases.”
    Here again, the figure was correct but misleading because it failed to put the number in perspective. If three hundred yogis in the United States suffered injuries of the vertebral arteries each year (the lowball estimate), 5 percent of that would be fifteen—fifteen yogis who lay dead after wounds to their vertebralarteries resulted in brain injuries serious enough to kill. And the real number of fatalities, despite the percentage being “less than” five, was probably higher given the large number of poses in yoga that involve extreme contortions of the