The Science of Yoga

“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 their bottoms high in the air, they keep their heads as close as possible to their knees. The movement ends with the students lowering themselves back down into the squat. Modern texts that describe that style of Frog recommend doing it anywhere from fifteen to more than one hundred times, its rhythms growing increasingly fluid and fast as the student warms up.
    The ten volunteers in the Davis study had led fairly sedentary lives. A condition for participation in the study was that they had engaged in no regular physical activity—including yoga—for the previous half year. Moreover, the researchers had the students refrain from all other forms of exercise. As with the Duke study, the researchers got around the measurement problem by performing the physiological assessments before and after the yoga training.
    Having gathered and analyzed the data, the Davis team got ready to present its findings to the world. That meant finding a reputable journal.
    Not all public representations of science are created equal. Journals range from bad to great. A minimum requirement for a good journal is that it conducts a process known as peer review—that is, it maintains panels of scientists working in the field who review any proposed article. They exercise what amounts to quality control, making sure a submission hangs together and, if weak, gets rejected or revised to address the inadequacies. Some of the world’s best journals are published by professional associations and have long histories. Science , for instance, was founded in 1880 with the financial support of Thomas Edison and is now published by the American Association for the Advancement of Science, a large professional group headquartered in Washington. The