The Science of Yoga

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 electrodesof 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.
    Dostálek pulled back at one point during his investigations to reflect on the big picture. He did so in the pages of Yoga Mimansa. In effect, his article was a thank-you to Gune’s institution.
    A misapprehension had arisen in science’s understanding of yoga, Dostálek argued. A number of investigators and studies had come to view the discipline as strictly calming and relaxing, seeing its methods as producing “states of lowered autonomic arousal and EEG deactivation.” But that was only half the picture, he argued. The other half told of excitation. His own studies, Dostálek said, revealed the magnitude of the stimulation. He noted that yoga’s physiological arousals were associated mainly with the kinds of practices and fast breathing described in Hatha Yoga Pradipika and Gheranda Samhita.
    Still, in his theorizing, Dostálek hewed to the conventional line. He portrayed the highs as simply helping the body gain new physiological flexibility, letting it not only rise to new heights but to hit new lows. Yoga worked in the main,