The Science of Yoga

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 advertisedeffects 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 extremeslowing” 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