The Science of Yoga

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 “many lively discussions” with her father, she recalled, and was delighted when he decided to do a yoga study.
    Amsterdam was determined to give yoga a serious look. Was the discipline all that it was cracked up to be? Was it, in fact, all that Dina needed to stay fit, to maintain a healthy heart? Could any practitioner reap the benefits? If so, yoga might join the elite club of rigorous sports and activities that public health authorities had singled out as highly beneficial—especially in preventing heart disease and the kind of cardiovascular illnesses that Amsterdam knew only too well.
    He worked with a team of specialists from the University of California at Davis, a good school in a highly respected system. Except for him, the three researchers came from the department of exercise science, anchoring the study in a solid analytic tradition. In terms of capabilities and intellectual depth, the team appeared to be quite strong.
    But the investigation, begun on an auspicious note, soon encountered a number of difficulties. The biggest was the lack of major financial support for the study, which forced the scientists to limit its size and design. They lined up just ten volunteers—one man and nine women. Compared to the Duke study, that was one-tenth the number of subjects. Moreover, their examination had no control group. The low numbers and the absence of controls increased the possibility that any observed changes might result from random variability rather than yoga. A final limitation was that the students were required to do a minimum of just two workouts a week for two months—a fairly short time in which to see the physiological effects of yoga. By contrast, the Duke study had proceeded twice as long.
    Even so, the yoga session itself was fairly intense, lasting nearly an hour and a half. It included ten minutes of breathing exercises (pranayamas), fifteen minutes of warm-up exercises, fifty minutes of yoga postures (asanas), and ten minutes of relaxation in the Corpse pose (Savasana). A centerpiece was the Sun Salutation. The students did two or three cycles ofits fluid movements, stretching and bending back and forth. In addition, the workout featured a number of other vigorous moves that went beyond yoga’s tradition of stationary poses. They included lunging forward on the legs and bobbing up and down in what the investigators called the Frog.
    Different schools of yoga mean different things when they talk about the posture. The energetic pose adopted by the Davis team was a newcomer to yoga, its origins unclear. No classic text mentions its repetitious movements. It starts with students squatting down, putting their hands on the floor, and then straightening out their legs. While raising