The Science of Yoga: The Risks and the Rewards

by William J Broad

  Katil Udupa was an ambitious physician at the Benares Hindu University, his professional life a blur of activity on the school’s sprawling campus outside the holy city on the Ganges. He was, in many respects, a successor to Paul—a man of Western medicine who became deeply interested in the healing arts of India. He also exhibited some of Gune’s passion for institution building. In 1971, Udupa founded the school’s Institute of Medical Sciences.

  He then proceeded to fall apart. After years of administration and its predictable crises, his outgoing nature started to crumble and Udupa ended up with a variety of nervous ills— chest pains, irritability, diffuse apprehension, emotional instability, and a sense of constant fatigue. The formal diagnosis was cardiac neurosis. We would call it burnout. Whatever the name, he was a nervous wreck.

  Udupa took up yoga and found quick relief that slowly developed into a deep sense of personal renewal. Intrigued, he began to study the medical literature about yoga and to investigate its potential for treating patients—especially those with chronic diseases that appeared to be linked to the kind of stresses and illnesses that he himself had experienced. His studies showed that yoga could dramatically improve a patient’s hormone profile, lowering, for instance, the high levels of adrenaline and other fight-or-flight hormones released in response to stress.

  The body always puts survival ahead of pleasure. A corollary of that principle is that stress can smother the flames of desire, and relaxation can create a situation where smoldering embers get fanned into a blaze.

  Udupa wondered if that kind of relationship held true on the biochemical level as well and, specifically, whether the reductions he was seeing in stress hormones meant that the body’s sex hormones were tending to increase. It was a smart question.

  He and his colleagues studied a dozen young men. Their average age was twenty-three, about half of them single, and half married. The volunteers underwent yoga training for six months. The lessons started out easy and, month by month, grew harder. The first month included the Cobra, the Spinal Twist, the Wheel, and the Full Lotus.

  Spinal Twist, Ardha Matsyendrasana

  New poses added over the months included the Plow, the Locust, the Bow, the Shoulder Stand, and the Headstand. The pranayamas included Bhastrika and Ujjayi, or Victorious Breath. Overall, by modern standards, the training was fairly rigorous.

  The scientists took urine samples from the young men at the start of the program and its conclusion. They found that the urinary excretion of testosterone rose significantly, its levels in some of the married men more than doubling. On average, the levels rose 57 percent. The results, the scientists wrote in 1974, suggested that yoga could prompt a “revitalization of the endocrine glands.” As for the mechanism, they speculated that yoga had improved the microcirculation of the blood through the men’s organs. In males, testosterone is made primarily in the testes but also to a lesser extent in the adrenal glands. It seems that poses such as the Bow, which exerts pressure on the genital region, might well serve as a stimulus to improved circulation.

  Bow, Dhanurasana

  In 1978, Udupa published a summary of the hormone findings in his book Stress and Its Management by Yoga. He noted the clinical evidence of the testosterone rise and attributed it to “considerable improvement in the endocrine function of the testes.”

  His hunch had proved correct. But Udupa made little of it. His finding was a particle of basic science in a blizzard of global research.

  Living peacefully on the Ganges a couple of hundred miles downstream from Benares and Udupa were advanced yogis who displayed a strong interest in science, their guru having named their ashram the Bihar School, after its location in Bihar state. It turns out they were interested in learning as well as teaching. A swami writing in Yoga Magazine, published by the school, called attention to Udupa’s testosterone finding. His brief reference was buried in an overview of Udupa’s yoga research. Still, the author, steeped in British English, noted how the hormone discovery suggested that yoga postures could improve “vitality and sexual vigour.”

  His appraisal was clear-eyed but rare. For the most part, science as well as popular and yogic literature ignored the finding. The Bihar yogis noted the testosterone rise in 1979, shortly after the publication of Udupa’s book. It seems plausible that the finding caught their attention not only because of their proximity to the research but because their own experiences had convinced them of its physiological truth.

  If science ignored the finding, investigators nonetheless threw themselves into acquiring a better understanding of testosterone. In Udupa’s day, the potent hormone was seen mainly as the force behind the male sex drive. Scientists knew that its levels fell with age, and that rises could lead to revitalization.

  But over the years, modern biology found many other ways in which the little molecule can influence behavior and sexuality—doing so in both males and females. Not the least significant, studies showed that it acts to improve mood and a person’s sense of well-being. It seems likely that the hormone forms a significant part of yoga’s cocktail of feel-good chemicals.

  Importantly, testosterone was shown to bolster attention, memory, and the ability to visualize spatial tasks and relationships. It sharpened the mind.

  Surprisingly, testosterone also turned out to play an important role in female arousal. While adult males tend to produce ten times more testosterone than females, scientists found that women are quite sensitive to low concentrations of the hormone. They make it in their ovaries and adrenals, and its production peaks around the time of ovulation—a phase of the reproductive cycle associated with increased sexual activity. A number of studies have linked testosterone rises in women to enhanced desire, erotic activity, intimate daring, and sexual gratification. The pharmaceutical industry is closely studying the hormone in hopes of finding a blockbuster drug like Viagra that it can sell to women.

  Udupa’s research got little attention not only because it was done in faraway India. Science for many centuries has been international in character, and back in the 1970s obscure articles could get quick attention if they revealed something bold and new. A factor that added to the disregard was the emergence of other studies that seemed to contradict Udupa’s testosterone findings. Thus, scientists aware of the work increasingly saw his conclusions as hollow. In short, the topic became muddled—a common problem in backwater fields of science that fail to get the kind of intense scrutiny that can rapidly clear up complicated topics.

  It was the low-testosterone findings that initially led me to conclude falsely that yoga had little to do with human sexuality.

  The inconspicuous challenge to Udupa’s findings grew out of an ambitious body of yoga research that sought to show how yoga could result in major benefits for cardiovascular health. It was the kind of thing that Dean Ornish had pioneered in the 1970s and 1980s, and that, over time, had received wide notice and emulation. In the research, scientists typically had subjects adopt not only Hatha yoga but other lifestyle changes as well, such as becoming strict vegetarians. In 1997, for instance, scientists at the Hannover Medical University in Germany reported on a study that examined more than one hundred adults who took part in a comprehensive program of yoga and meditation for three months. The setting was a yoga school that had its own fields, garden, and kitchen, and where the subjects adhered to its regular vegetarian diet. The results showed that participants lost weight and reduced their blood pressure and heart rates, significantly lowering their risk factors for heart disease. That was the study’s main question, and scientists hailed the results as showing yoga’s benefits for cardiovascular health.

  But their report also noted that testosterone fell significantly. It was an aside—a minor finding in relation to the main question. But the idea nonetheless got lodged in the scientific literature.

  Now, as it turns out, vegetarianism alone reduces the body’s levels of testosterone, and that kind of reduction has been understood for a long time. The vegetarian fact
or meant that yoga most likely had nothing to do with the reported testosterone drops. Even so, the relationship had become cloudy. In addition, the muddle probably grew because of the structural bias in science that favors new findings over old. For whatever reason or reasons, fallacies gained currency.

  “You won’t boost testosterone doing yoga,” Al Sears, a popular author and Florida doctor specializing in men’s health, declared in a leaflet. “Try wrestling, boxing or karate instead.”

  The confusion meant that testosterone fell off the map for writers of yoga guides and how-to books. Its disappearance was understandable. At best, news of the hormone’s reduction in the body was puzzling given the personal experience of revitalization and, at worst, seemed like something of an embarrassment. How could yoga do that given testosterone’s importance for improving mood, attention, and sense of well-being—not to mention sex?

  One way that popular yoga handled the ambiguous situation was by hailing the discipline’s sex benefits while omitting any mention of testosterone. The 2003 book Real Men Do Yoga reported that the discipline “recharges your sex life” with “Viagra-like effects.” But it made no mention of the potent little hormone.

  Science kept inching forward, despite the jumble. In Russia, three decades after Udupa, investigators reported new evidence that echoed his findings. The team leader was Rinad Minvaleev, a physiologist who practiced yoga and led expeditions to the Himalayas. Among his interests was the Tibetan yoga of Tummo. It generates inner heat that is said to protect its practitioners from extreme cold. A photograph of Minvaleev in the Himalayas shows him sitting atop a glacier wearing nothing more than a swimsuit.

  His team at Saint Petersburg State University and the city’s Medical Academy of Postgraduate Studies undertook a yoga study with a very narrow focus. The subjects included seven males and one female, their ages ranging from twenty-two to fifty. The volunteers were taught how to do the Cobra and to hold it for two to three minutes. The team limited itself to studying the physiological repercussions of just that one posture.

  The Cobra, or Bhujangasana, from the Sanskrit for “snake,” is one of 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 that scholars 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 55 percent—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 with a dozen or more electrodes, switch on the machine, and peer into a hidden world. The EEG monitors faint currents of bioelectricity running across the brain and amplifies them roughly a million times, producing a graphic record of wavy lines. By 1973, Dostálek had become so proficient at electroencephalography that he was named director of the Institute of Physiological Regulations of the Czechoslovak Academy of Sciences. He worked in the heart of Prague.

  Soon Dostálek turned his attention to his personal interest, yoga. One experiment focused on a single exercise—a kind of minimalism that reduced the influence of potentially confusing variables, much as the Russians had done in their Cobra study. The pose was Agni Sara, Sanskrit for “fanning the flame.” Named after the Hindu god of fire, it had nothing to do with pop yoga or sleek gyms but instead arose from the misty world of Tantra. Modern gurus held the practice in such esteem that some recommended doing it daily even if time allowed no other exercise.

  Doing Agni Sara properly can be difficult. The yogi leans over from a standing position, knees slightly bent, hands on thighs. After a deep exhalation, he or she holds the breath out and repeatedly pulls the stomach in and out. The objective is to tug backward toward the spine, then relax the stomach and let the abdomen fall forward. The cycle is repeated ten or fifteen times before the yogi inhales. The Gheranda Samhita tells students to do Agni Sara one hundred times. Swami Rama, the modern yogi known for feats and philandering, suggested doing it one hundred and fifty times daily.

  Over the decades, science has learned a lot about the target of such undulations. The waves going through the lower abdomen massage the internal organs and nerves of the reproductive system. The area is often characterized as an erogenous zone.
Masters and Johnson reported that, during sex, contractions of the abdominal muscles build into spasms that amplify the actions of pelvic thrusting.

  Undulations higher in the abdomen massage the region devoted to digestion and its specialized nervous system. The complexity of the area is so great that scientists liken its network of nerves and neurotransmitters to a second brain. The system envelops the viscera in whorls of nerves and sensory receptors in order to exert control over the complex processes of digestion and elimination. To that end, it makes dozens of different hormones and neurotransmitters. Individuals can sometimes feel the subtle workings of the second brain as gut instincts, intestinal unease before a talk, or butterflies in the stomach. It can feel emotions and remember experiences. Stress and repressed feelings can upset its functioning, darken moods, and harm overall health.

  For his experiment, Dostálek chose an elite subject, a disciple of Gune’s who had done yoga for more than three decades. The thumpings of Agni Sara sent waves of stimulation rippling through his abdominal cavity, and the electrodes of the EEG revealed bursts of brain excitation. The spikes grew in size as the pounding intensified.

  In a 1983 report, Dostálek called the peaks “very significant.” The web of electrodes on the yogi’s head let the electrophysiologist pinpoint the origin of the bursts. They arose from the central parietal lobes—a region of the brain responsible for processing body sensations, including touch and pressure. It is the parietal lobes that hold a miniature sensory map of the body whose anthropomorphic expression is known as the homunculus—a tiny human figure distorted to show the relative importance of sensory inputs to the brain. The homunculus has relatively big lips, hands, and genitals.

  Dostálek widened his investigations to include more experienced yogis and more Tantric poses as well as fast breathing, including Bhastrika, or Breath of Fire, as well as Kapalbhati, or Shining Skull Breath. The blitz set off large bursts. Dostálek found that the spikes now built with greater force, cresting in frenzied excitation. In a 1985 report, he called the peaks “paroxysmal,” in other words, like a seizure or convulsion. He noted that other scientists had previously observed such readings among people in sexual climax.