The Science of Yoga

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 reinflate. Immediately, the symptoms of labored breathing went away. The woman, after a week of recovery, underwent a procedure for removal of the tube.
    In 2004, the doctorsfrom the Berkshire Medical Center documented the unusual case in Chest , the respected journal of the American College of Chest Physicians. They noted that an imaging scan of the woman’s chest had revealed no lung pathologies that might account for the pneumothorax, and concluded that the rupture was a direct result of yoga breathing. The case was without known precedent, they said, and showed that “adverse side effects can occur when one pushes the body to physiologic extremes.”
    In this case, the yoga community took notice and reacted. The days of denial and evasion were ending rapidly as the once-secretive topic of yoga injuries increasingly went public.
    A yoga teacher and a medical doctor who had advised the teacher in developing a program for people with breathing disorders wrote a joint letter to Chest. The two, based in Sacramento, California, agreed that the rapid breathing exercise “most probably induced the pneumothorax” and backed the report’s cautionary advice. But they said its warning about pushing the body to physiologic extremes created a false impression that “appears to unjustly blame all yoga techniques. This is not appropriate for a discipline that has generally been practiced safely for not hundreds, but thousands of years.”
    The yoga teacher—Vijai P. Sharma—took to the pages of the International Journal of Yoga Therapy to discuss the case and argue for the relative safety of Kapalbhati and other yoga breathing exercises. But his argument was heavy with caveats. He drew a distinction between fast and slow breathing, saying yoga’s quick styles posed greater risk. Fast breathing, he wrote, “may reinforce or worsen preexisting structural or functional problems.” Finally, Sharma enumerated a long list of safety guidelines and heightened risk factors (diabetes, chronic hypertension, persistent head pain) that made fast breathing seem like it was generally a risky venture.
    Unless students exercise “out-of-the-ordinary patience and self-control,” Sharma warned, “rapid breathing techniques such as Kapalbhati and Bhastrika are likely to be performed incorrectly and prove harmful in the long run.”
    Yet another case that came to light featured an aging yogi. The man had done yoga since his thirties and was sixty-three when the trouble hit. His daily practice includedthe Headstand. He suffered no neck or back problems until one day he began to feel tingling and numbness in his fingers and toes. Over a few months, his legs and arms grew increasingly weak, and he began to experience the urge to urinate frequently.
    His doctors saw the symptoms as classics of quadriplegia—limb weakness due to an injured spinal cord. Diagnostic imaging showed a region of disk