...But a growing body of medical evidence supports Black’s contention that, for many people, a number of commonly taught yoga poses are inherently risky. The first reports of yoga injuries appeared decades ago, published in some of the world’s most respected journals — among them, Neurology, The British Medical Journal and The Journal of the American Medical Association. The problems ranged from relatively mild injuries to permanent disabilities. In one case, a male college student, after more than a year of doing yoga, decided to intensify his practice. He would sit upright on his heels in a kneeling position known as vajrasana for hours a day, chanting for world peace. Soon he was experiencing difficulty walking, running and climbing stairs.
Doctors traced the problem to an unresponsive nerve, a peripheral branch of the sciatic, which runs from the lower spine through the buttocks and down the legs. Sitting in vajrasana deprived the branch that runs below the knee of oxygen, deadening the nerve. Once the student gave up the pose, he improved rapidly. Clinicians recorded a number of similar cases and the condition even got its own name: “yoga foot drop.”...
