The Science of Yoga: The Risks and the Rewards (18 page)

And it has
nothing
to do with getting more or less oxygen into the practitioner’s body, contrary to innumerable yogis and gurus, video discs and yoga books, blogs and newsletters. Nevertheless, some yoga authorities go so far as to issue delusional warnings.

“You’re not used to so much oxygen pouring into your system!” Choudhury, the guru of hot yoga, cautions students who do his deep breathing and begin to feel dizzy. He says nothing of big carbon dioxide drops, the real cause of blackouts.

The blunders go on and on. Breath of Fire “increases oxygen delivery to the brain,” said
Kundalini Yoga
, richly illustrated and highly accessible to beginners. Actually, as we just saw, it does the exact opposite, dramatically so.

The Complete Idiot’s Guide to Yoga
praises the discipline’s breathing as “one of the best things you can do to keep your body filled with oxygen.” The advertised
effects sounded a lot like the calm serenity that high carbon dioxide levels can induce.

The confusion about yoga breathing as a way to fill the body and brain with oxygen goes far beyond simple misstatements and their dissemination through countless books, articles, and videos. Of late, it has spread to a whole new style of the discipline.
Oxygen Yoga
promotes itself as beneficial “for anyone in need of more oxygen.” Its authors have a line of books. The newest—
Oxygen Yoga: A Spa
Universe
, published in 2010—recommends that health resorts adopt the style for “added revenue.”

It is said that every disaster has a silver lining. In a similar way, the failure of yoga investigators to find miracle workers who could stop their hearts and live without air led to a major advance in understanding the brain. And that discovery in turn revealed one of the most important ways that yoga can sway emotion. It happened in the decades after Behanan did his experiments, from roughly the 1940s to 1970s.

The lesser discoveries ended up revising a major tenet of the medical world—that the human body has two nervous systems that are entirely distinct. The newer one starts in the outer brain and radiates out in the nerves that let us move our skeletal muscles and go about our daily lives. The older one begins in the lower brain and regulates the internal muscles, the organs, the instincts, and other primal functions. It is called the autonomic nervous system.

The medical credo of the day held that its activities were automatic and, with notable exceptions (such as breathing), beyond the control of the conscious mind. But scientists who studied gifted yogis kept documenting abilities that contradicted this tidy picture. In study after study, they found that yogis could seize control of autonomic functions and make dramatic changes of body activity. The automatic system, it turned out, contained options for all kinds of manual overrides.

One of the scientists was Thérése Brosse, a French cardiologist who examined Krishnamacharya. She and her colleagues wrote extensively on how advanced yogis could unwind in surprising ways, slowing the heart rate and blood flow. Another was Bagchi. Despite his campaign to expose yogic miracles as false, he documented wide yogic control over autonomic functions once considered beyond reach. A 1957 paper of his found “an extreme
slowing” of such fundamentals as respiration and heart rate. He concluded that overall, yoga brings about “deep relaxation of the autonomic nervous system.”

The star of autonomic control was an Indian yogi named Swami Rama. Among other things, laboratory studies showed that he could use his mind alone to change the temperature of his hand, creating a gap of up to eleven degrees across his palm.

The autonomic system is bifurcated, and the studies showed that advanced yogis could seize control of either side. The sympathetic side promotes the body’s fight-or-flight response, inhibiting digestion and moving blood to the muscles for quick action. It does so partly by telling the adrenal glands to squirt out adrenaline, a natural stimulant that speeds up body functions. Early biologists called it “sympathetic” because they saw its functions as acting in concert or
sympathy
with one another—all at once. The other side is known as the parasympathetic. It governs the body’s rest-and-digest functions, calming the nerves, promoting the absorption of food, and curbing the flow of adrenaline.

The sympathetic system is the body’s accelerator, and the parasympathetic the brake. Working together, the two manage the body’s overall energy flow, one preparing for its expenditure, the other for its conservation. For instance, the sympathetic system raises the heart rate, and the parasympathetic slows it down.

The two also wield control over human moods and emotions rooted in primal energy states—the ups and the downs, the exhilarations of Iyengar and the quietudes of Behanan. The inner states resonate with some of the most fundamental of all human emotions—whether individuals feel safe and protected or threatened and endangered. They reflect not only our survival instincts but the mood swings of childhood.

The investigations showed that yogis had a special talent for applying the brake. Their adroit slowing of the metabolism and related functions was especially impressive in that it overcame a strong evolutionary bias. The demands of survival mean that the body, left to its own devices, always favors the accelerator. After all, the sympathetic nervous system is essentially a means of emergency response and easily aroused, keeping the body ready for battle or retreat, awash in adrenaline.

Yogis have pressed these pedals for ages. But recently, a new breed of practitioner has arisen who can not only work the pedals but draw on a wealth of contemporary science
to explain the process and how it relates to the experiences of regular practitioners.

I speak of Mel Robin.

Many yoga teachers have a reverential aura. Not Robin, not on a rainy Saturday in Pennsylvania as he strode into a crowded yoga studio, his manner relaxed, his beard trim. New Age music played softly in the background.

“My name is Mel and I wrote this music,” he quipped, getting a laugh.

Someone asked if he performed it, too.

“Don’t get smart,” he replied. And with that, Robin shattered the usual atmosphere.

The Yoga Loft of Bethlehem sat atop an old brick building that seemed to date from the city’s steel days. It had bare wooden floors and large windows. The studio had put aside its regular Saturday classes for a special program featuring Robin on “The Science of Inversions”—poses in which the feet or torso go above the head. The ads suggested that students bring along a copy of his
Physiological Handbook for Teachers of Yogasana
or buy one at the studio’s shop.

Women in their thirties tended to dominate the room. Several were yoga instructors, as the class was advanced. Robin was seventy-three and, in typical yoga style, failed to look or act his age.

He sat on the bare wooden floor, stretching and talking, and over the next three hours took us through some of the nuances of autonomic control. His focus that day was not the kind of mental gymnastics that Rama had displayed. Rather, it was explaining how normal poses can result in autonomic shifts.

Headstands, he said, tend to excite the fight-or-flight response, especially in nervous beginners. By contrast, he added, the Shoulder Stand pressed the parasympathetic brake, soothing the spirit and making it “one of the most relaxing postures in yoga.”

We paired off and Robin, a teacher in the Iyengar style, toured the room helping twosomes do Shoulder Stands. When he got to me, I asked if more was known about the reasons for the relaxation.

Robin said the pose calmed because it seized control of one of the most important functions of the autonomic system—the regulation of blood pressure.

It is well known
that good health depends on the pressure staying in a narrow range. If it drops too low, the brain gets insufficient blood and we get dizzy, weak, and faint. In extreme cases, organs can fail, producing such breakdowns as cardiac arrest. High blood pressure has its own hazards, though long-term rather than immediate. It stresses the heart and arterial walls, producing hypertension. This is a risk factor for stroke, heart attack, and kidney failure. Because of such dangers, the human body over the ages has evolved a striking array of sensors and defense mechanisms that constantly take pressure readings of the blood vessels and make suitable adjustments.

Robin said the Shoulder Stand tweaked one particular kind of sensor. It lay in the carotids—the major arteries that run through the front of the neck carrying blood to the brain. The carotid sensors make sure the brain gets the right amount of blood and, given the brain’s importance, get serious attention. Sensors embedded in the arterial walls monitor bulging or contracting that indicate changes in blood pressure.

Shoulder Stand,
Sarvangasana

But in the Shoulder
Stand, Robin said, the chin presses deeply into the neck and upper chest, clamping down on the carotids and making the local pressure very high. That rings alarm bells and the parasympathetic brake flies into action. It assumes that the delicate tissues of the brain are reeling from too much blood and orders the heart and the circulatory system to compensate with pressure cuts. The main response signals go through the vagus—the large nerve that starts in the brain stem and wanders among the lungs, heart, stomach, and other abdominal organs.

Robin clapped his hands to illustrate the urgent nature of the parasympathetic commands.

“Don’t pump so often. Don’t pump so hard. Open the diameters. Vasodilate”—the term for vessel relaxation that allows blood to flow at a more leisurely pace.

I thanked him. Gune may have recommended the Shoulder Stand to Gandhi for its calming effects, but he had nothing on Robin in explaining how it worked.

Robin volunteered that the scientific approach to understanding the poses made some yogis uncomfortable.

“There are people who say, ‘You’ve crossed the line. That’s not yoga. Look at Patanjali. There’s nothing about the workings of the sympathetic nervous system.
’

“They are very, very traditional people,” he continued. “My own feeling is—I agree. It’s not yoga. It’s about yoga and understanding it, and that lets you do better yoga.”

And with that, Robin turned his attention to other students.

Better yoga.
The phrase echoed in my head. A few days later, I called Yoga Loft and signed up for a series of four courses that Robin planned to teach on the science of yoga. The last focused entirely on the autonomic nervous system.

Right off, he cast the topic in a new light. Most portrayals stress psychological factors—such as existential threats that prompt the fight-or-flight response, or peaceful interludes that bring about rest-and-digest states of contentment. But Robin said the systems could be stimulated not only by environmental factors but from the bottom up by conscious actions. An example, he said, centered on the muscles.

“If you’re frightened, your muscles get tense,” he said. “But if you do muscle work, that also excites the sympathetic nervous system.” It was a fascinating observation that
had all kinds of implications for life and explaining the influence of yoga postures.

Robin pointed to a place in his book that listed which parts of the body came under autonomic control. The table, spread over four pages, described more than one hundred functions— everything from sleep and gastric secretions to vasoconstriction and shivering. Each entry was followed by a reference number, or several reference numbers, that pointed to the book’s end section of scientific reports. The table seemed to represent a labor of love that summarized decades of research.

Robin had us turn to another page that listed nine unusually potent effects of sympathetic stimulation. They include a quicker heartbeat (to prepare for action), dilated pupils (to admit more light for better attention to potential threats), and changed blood chemistry (to stimulate clotting in case of bleeding). Most people have no conscious control over such autonomic responses. But two items on the list stood out as relatively easy to influence—muscle tone and respiration rate. Robin called them keys to the hidden world of autonomic control.

We practiced poses that worked the muscles, seeking to excite the sympathetic nerves. “Any kind of exercise, any kind of muscular work” will do it, Robin told us. He added that the same held true for respiration. “Anything you do to speed up your breath will speed up most parts of the sympathetic system.”

It was a fascinating idea. His activity rule, given the list of autonomic functions we had just looked at, suggested that a disciplined individual could gain leverage over dozens of the body’s most important and inconspicuous functions. His rule also suggested that different Hatha styles had very different autonomic effects. For instance, Ashtanga, with its fast, flowing movements and its emphasis on Sun Salutations, works the muscles a lot and would thus stimulate the sympathetic system. In contrast, Iyengar, with its emphasis on static poses, would seem to lend itself to parasympathetic dominance.