The Science of Yoga

Hatha’s oldest poses. It dates from the pure Tantra days before the era of sanitization and takes center stage in such works as the Gheranda Samhita —a holy book of Hatha thatscholars date to the transition between the seventeenth and eighteenth centuries. Parts of Gheranda Samhita , no less than Hatha Yoga Pradipika , read like a sex manual, full of references to the perineum, scrotum, penis, and so forth, as well as acclaim for the goal of stoking “the bodily fire.” Bhujangasana is praised as an igniter. As the yogi performs it, the book says, “the physical fire increases steadily.” The book describes the concluding step of the yogic journey as “pleasures, enjoyments, and ultimate bliss.”
    Easy to do, the Cobra is basic to beginning yoga and was one of more than a dozen poses that Udupa’s subjects had performed. His volunteers began the Cobra in the first month of their practice, and thus did it longer than many of the other postures. The student, lying facedown, legs together, simply brings the hands forward and pushes down on the palms, raising the chest and head. Done correctly, the pose exerts much pressure on the genitals. As Iyengar puts it delicately in Light on Yoga , the pupil should lift the trunk “until the pubis is in contact with the floor and stay in this position.” He adds that the student, once up, should “contract the anus and the buttocks,” a move that increases the downward pressure.
    In designing their experiments, the Indian and Russian teams took very different approaches and had very different goals in mind. The Indians looked at cumulative effects of yoga over six months, while the Russians looked at the repercussions of just one session. The Russian team simply drew blood before and after the volunteers did the Cobra, taking the samples no more than five minutes apart. It was a snapshot versus a movie. And because of the shorter period of training, the Russian results seemed preordained to show a more modest testosterone rise.
    In their report, published in 2004, the Russians first told of changes they observed in levels of cortisol—a hormone that, as part of the body’s reaction to stress and sympathetic stimulation, raises the blood sugar and blood pressure in preparation for an individual to flee or fight. On average, cortisol fell 11 percent.
    As for testosterone, the team reported an average rise of 16 percent. Individual males showed increases that varied anywhere from 2 to 33 percent.
    But the gold star for the biggest increase went to the study’s lone female. Her testosterone readings shot above those of the males and kept rising to reach 55percent—rivaling the increases that Udupa’s male subjects had experienced after doing yoga for six months.
    The Russian scientists, in their report, put their celebrity in the spotlight. The photo showed the attractive young woman clad in a bikini, rising into the Cobra, a picture of vitality and vigor. She almost seemed to glow.
    Yoga as an exercise seems fairly distinctive in its ability to raise testosterone levels. Over decades of study, scientists have consistently found that endurance sports have just the opposite effect. Runners, for instance, show lower testosterone levels than nonrunners. The declines may result from the continuous stress of pounding the pavement.
    Scientists looking into the relationship between yoga and sexual revitalization cast their gaze far beyond hormones and the body’s endocrine system. In time, they zeroed in on a more central organ—the brain. Again, the research took place outside the United States, this time in Czechoslovakia. One of the main investigators held both medical and doctoral degrees.
    Ctibor Dostálek fell for yoga in his early forties when he was already a skilled Czech neurophysiologist and longtime academic working in Prague. The year was 1968 and his deep personal interest altered the trajectory of his career. It sent him to India and Gune’s ashram. His interest began with the sanitized version of the discipline but soon encompassed old Hatha. In all, he went to India eleven times. His research examined not Headstands and Sun Salutations but various kinds of stimulations out of the pages of Gheranda Samhita and Hatha Yoga Pradipika.
    Dostálek’s main tool was the electroencephalograph, or EEG. Compared to Gune’s X-ray machine, it was all nuance and subtlety, giving a glimpse of firing neurons in action. He would cover the scalp of an advanced yogi