The Science of Yoga

to do with the prickly nature of intellectual turf.
    The academic world has a number of research fields that lavish attention on questions of fitness. The disciplines include biomechanics, kinesiology, exercise physiology, nutrition, physical therapy, and sports medicine, among others. Today, sports scientists draw on a wealth of instrumentation and software to conduct careful studies of exercise and athletics. Whole businesses do nothing but sell the equipment. Major universities have whole departmentsthat do nothing but conduct fitness studies and publish the results in dozens of specialty journals, including the Journal of Exercise Physiology and The American Journal of Sports Medicine. The field’s textbooks tend to be gargantuan in size and extraordinarily detailed in content. The professional societies of the field include the American College of Sports Medicine—the world’s largest organization of scientists devoted to the study of athletics. Its standing is such that governments around the globe routinely adopt its guidelines for physical activity in campaigns meant to promote public health.
    Yoga’s fitness claims fall squarely into this whirl. A philosopher would say they fall within an existing paradigm. The situation is very different from the case with yogic declarations about, say, body currents and spiritual renewal.
    As a result, a relatively large number of scientists (a growing number of them yogis) have applied the instruments and the techniques of the academic sports establishment to the study of yoga’s fitness claims. The results, as we shall see, raise significant doubts about some of modern yoga’s most prominent declarations.
    A complicating factor is that yoga, taken as a singular activity, represents an oversimplification rooted in the discipline’s timeless image. A better word would be “yogas,” denoting the evolution of many styles over the centuries—with new ones appearing all the time. Three phases stand out. First was the original Hatha, which debuted as a forceful branch of Tantra. Then, as we saw in the previous chapter, the yoga innovators of the early twentieth century produced a sanitized Hatha. Today, the newest styles represent another step in yoga’s development, their moves more vigorous than the old. It turns out that modern yoga, by accident or design, has lost much of its contemplative nature and adopted some of the sweatiness of contemporary exercise.
    Gune taught a style of yoga that epitomized the slow, tranquil approach. His emphasis was on holding poses for long periods of time and learning how to relax even amid extreme states of bending, flexing, and upending. It was a point he drove home with his measurements of how challenging inversions were gentle on the heart. By contrast, the newer styles tend to be hyperkinetic, some done to the beat of rock music. The objective is to get the heart pounding and the body exhausted. That makes them more aerobic (“requiring air”)—in other words, more focused on reinvigorating the blood. Incontrast to Gune’s style of yoga, the new goal is to maximize rather than minimize the energetic costs.
    Brands that focus on aerobics include YogaFit and Power Yoga. To a lesser extent, the vigor extends to older styles such as Ashtanga and Vinyasa. And then there is Bikram. “My classes are so hard,” Choudhury boasts, “you use your heart more than if you run a marathon.”
    Fortunately, that kind of pronouncement is open to investigation.
    The analytic lens of the sports establishment began to form in the nineteenth century as health authorities struggled to identify universal factors that determine the origins of human fitness. The question was seen as urgent. Around the globe, waves of people were leaving farms and giving up agrarian lifestyles that had kept them physically active from dawn to dusk. Medical experts agreed that the new sedentary lifestyles of the cities were often unhealthy but could achieve no consensus on what forms of exercise to recommend—even as entrepreneurs and hucksters got rich promoting their own methods. It was an age of dumbbells and medicine balls, of weighted clubs and chest expanders, of gimmicks and gadgets. The scientific goal was to develop objective standards that would let investigators cut through the competing claims and document what was truly beneficial. The resulting programs of exercise were seen as important to help city dwellers improve their health, avoid fatigue, and