The Science of Yoga

neck. Maybe it was thirty fatalities annually, and maybe three hundred over a decade. Globally, the fatalities might number in the thousands. It was an open question.
    The article ended with a list of cautions—listen to your body, move slowly, avoid thrusting or jerky motions, go up to the point of resistance but never beyond. Its last warning focused on the neck. It advised students, especially beginners, to avoid putting the relatively thin, upper part of the spine in a position where it had to support a lot of body weight.
    The magazine’s attempt to deal with the sensitive topic appears to have made few waves in the world of yoga practitioners. Outside of Yoga Journal , the article got no general notice on the Internet from blogs, studios, or magazines, unlike the magazine’s aerobics news. It rapidly sank into the void of cultural forgetfulness.
    The subject of stroke nonetheless proved to be a topic of continuing worry among yogis—even if the discussions were superficial. More than three decades after Russell’s warning, after the clinical reports, after the crystallization of medical concern, after the debut of the X-rated exercises, and after the threat summary in Yoga Journal , practitioners could still get lost in a cloud of uncertainty.
    In 2004, the Internet buzzed with discussion about a woman of thirty-nine who did Power Yoga nearly every day and had suffered two strokes that threw her into the hospital. Her doctors, a friend reported, called her yoga routine the apparent cause and advised her to drop the practice. The woman did a beautiful Shoulder Stand, her friend reported in a discussion forum. But she wondered if the identified source of the trouble could possibly be accurate.
    “Misinformed and misguided,” one discussant said of the attending physicians. “Blaming yoga for a stroke is absurd.”
    During this period, yoga in America felt the sting of bureaucratic oversight for the first time as states began to regulate the training of teachers. They did so under the banner of consumer protection, the effort expanding in step with the new disclosures and the rising debate.
    Regulators said licensing the schools would let states enforce basic standards and protect customerswho typically spend thousands of dollars on training courses, as well as improving the quality of the experience for their students. “If you’re going to start a school,” said Patrick Sweeney, a Wisconsin licensing official, “you should play by a set of rules.”
    A disturbing new kind of injury came to light even as states began their regulatory effort. The case involved a woman of twenty-nine who was undergoing teacher training at Kripalu, the yoga emporium in the Berkshires. One night, she was practicing the rapid breathing method known as Kapalbhati Pranayama, or Shining Skull Breath—the form of Breath of Fire that Bikram students do as a grand finale. The next day the woman awoke with shortness of breath and pain in her left chest. Her symptoms slowly worsened, and she was taken to the Berkshire Medical Center, just up the road from Kripalu in Pittsfield, Massachusetts.
    The doctors in the emergency room, upon seeing the woman’s labored breathing and learning of her troubles, quickly put her on oxygen. The urgent question was what had gone wrong.
    Lungs are like sponges that soak up air. They are highly elastic but largely passive. During a breath, the chest wall expands, forcing the sponge to draw in air. During exhalation, the sponge contracts and air goes out. It is mainly the action of the chest wall that governs the rhythms of the respiratory cycle. The sponge can do little on its own without the application of external force.
    A quick X-ray showed that the woman was suffering from a serious failure of this mechanism, known as pneumothorax (from the Greek words for “air” and “chest”). The condition arises when air leaks into the space between the lung and the chest wall, loosening the usual grip of the wall and letting the sponge collapse. The lack of movement and breath can be life-threatening, especially if it involves both lungs. In the woman’s case, the pneumothorax had partly collapsed her left lung.
    In an emergency procedure, the doctors administered a local anesthetic, cut a hole between her ribs, and inserted a small tube that penetrated her chest wall and entered the pleural space. Then they extracted the unwanted air, allowing the chest wall to come back into play and her lung to