The Science of Yoga

are quite different from yoga’s static postures. The situation is similar to what we experience in terms of gait. When standing motionless, we are, by definition, stationary. But once in motion, we can move forward in a number of ways: walking, jogging, running, or racing ahead as fast as we can. It depends on what we want to do.
    The Sun Salutation appears to be fairly recent in origin. The Encyclopedia of Traditional Asanas —published in India by the Lonavla Yoga Institute, founded near Gune’s ashram by one of his students—draws on nearly two hundred books and unpublished manuscripts to describe many centuries of pose development but says nothing about the Sun Salutation. So, too, the asana makes no appearance in the how-to guides of Gune (1931), Sivananda (1939), and other early teachers.
    The pose most likely arose in the early twentieth century as the Mysore palace and Krishnamacharya mixed traditions of British gymnastics and native wrestling. Whatever its exact origins, the Sun Salutation debuted as an important new feature of Hatha yoga in the 1930s, spreading slowly through India and the world. The idea behind the pose and kindred postures was what Krishnamacharya called Vinyasa ( vi denotes “in a special way” and nyasa “to place”). It stood for the flowing movements that he developed to join the individual poses into a new kind of graceful activity. The result was a kind of yoga ballet.
    In the West, students of yoga learned about the pose in a number of ways. Krishnamacharya’s student Sri K. Pattabhi Jois played an important role in popularizing the series of movements and the Vinyasa system, calling it Ashtanga(or eight-limb) yoga, after the sutras of Patanjali and their eight rules. Starting in the late 1960s, Westerners began traveling to Mysore to study yoga with Jois. Slowly Ashtanga grew in popularity, especially among the physically ambitious in the West who were seeking yoga’s most athletic expressions. The aggressive style required skill and power, and could leave a student bathed in sweat.
    Science looked into Ashtanga as the style gained in popularity and found that, compared to traditional yoga, it posed a greater challenge to the heart. One study examined sixteen volunteers. The human heart beats about seventy times per minute. On average, the hearts of the yogis quickened to ninety-five beats while doing Ashtanga, compared to eighty beats during conventional Hatha. The Ashtanga factor represented a rise of roughly 20 percent.
    The more difficult question was whether the increased thumping of the heart that resulted from faster poses and faster styles translated into measurable improvements in cardiovascular fitness. That soon became the question.
    Ezra A. Amsterdam was hitting new highs in his career when yoga caught his eye. A senior cardiologist at the medical school of the University of California at Davis, he had devoted himself to the study, practice, and teaching of ways to prevent heart disease, the nation’s number one killer. He was prolific. His résumé boasted hundreds of articles. Recently, he had even founded a journal— Preventive Cardiology —the first of its kind, published by John Wiley & Sons, a respected firm. Amsterdam’s own studies ranged from investigations of diet and exercise to drugs and therapy as ways to promote a healthy heart and fend off cardiovascular disease. He lived in sunny California and practiced what he preached, maintaining a trim figure into his sixties.
    Yoga as a field of scientific inquiry seemed wide open to Amsterdam, his interest stimulated by what he saw as “the lack of objective study.” Growing numbers of people were practicing yoga, and doing so in new, innovative ways that were often quite vigorous. A fresh look at the relationship between yoga and aerobics seemed to beckon.
    Another factor was his daughter. Dina suffered from an eating disorder and was twenty-five pounds overweight when she starting doing yoga. It worked like a charm. The discipline helped her shed weight, feel good about herself, andget in excellent shape. She studied with Rodney Yee, a yoga star, taking his advanced teacher training course. Dina became a devotee of the discipline and proceeded to teach classes in the San Francisco area. She had a big smile and a reputation for rigor, sensitivity, and infectious enthusiasm. Dina—a graduate student at Stanford University—also had a deep interest in the science of yoga and wellness. She had