The Science of Yoga

imposition of controls meant to increase the likelihood that any observed changes were real rather than false clues or statistical flukes. Thus, the subjects in the metabolic chamber engaged sequentially in three different activities—reading a book, doing yoga, and walking on a treadmill. To provide a more detailed basis for comparison, the scientists had the subjects walk on the treadmill at different speeds. The imposed rates were two miles per hour and three miles per hour, the latter a fairly vigorous pace.
    The yoga was pure Ashtanga, the brisk, fluid style descended from Krishnamacharya. The workout began with twenty-eight minutes of Sun Salutations followed by some twenty minutes of standing poses such as the Triangle and Padahastasana, a forward bend in which the student grabs the feet and brings the head down to the knees. It ended with eight minutes of relaxation in the Lotus position and the Corpse pose. Overall, the yoga session lasted nearly an hour. Its strong focus on Sun Salutations made the routine one of the most vigorous to undergo careful examination.

    Hands to Feet, Padahastasana
    Despite the added zing,the scientists concluded that the yoga session failed to meet the minimal aerobic recommendations of the world’s health bodies. Its oxygen demands, they reported, “represent low levels of physical activity” similar to walking on the treadmill at a slow pace or taking a leisurely stroll.
    The only glimmer of cardiovascular hope centered, once again, on Sun Salutations. The New Yorkers found the oxygen challenge of the pose “significantly higher” than for the slow treadmill. A practice incorporating Sun Salutations for at least ten minutes, they wrote, may “improve cardio-respiratory fitness in unfit or sedentary individuals.” But the flip side, the scientists added, was that the posture offered few heart benefits for seasoned practitioners.
    Seeking a wide context, the scientists were careful to note that other research had demonstrated that yoga aided the body and mind in ways that extended far beyond athletics and aerobics. Hagins, the lead researcher, remarked in a university news release that the discipline had “positive health benefits on blood pressure, osteoporosis, stress and depression.” Yoga, he added, “may convey its primary benefits in ways unrelated to metabolic expenditure and increased heart rate.”
    That kind of prudence became the standard view in the world of science. Decades of uncertainty ended as a consensus emerged that yoga did much for the body and mind but little or nothing for aerobic conditioning. The California study receded as an anomaly, and the investigations in Texas, Wisconsin, and New York got cited repeatedly and respectfully in the scientific literature. Science and its social mechanisms had assessed a big claim and found it wanting.
    In 2010, a review paper documented the new accord. In the halls of science, the review article is a hallowed tradition because of its pithy generalizations. It gives a critical evaluation of the published work in a particular area of research and then draws conclusions about what is legitimate progress and what is not, what is good and what is bad. By definition, it weighs all the evidence. Given the rapid advance of science around the globe, as well as the soaring numbers of reports, such analyses are seen as increasingly important to upholding the standard of wide comprehension. Whole journals do nothing but publish review articles.
    The 2010 paper examinedmore than eighty studies that compared yoga and regular exercise. The analysis, by health specialists at the University of Maryland, found that yoga equaled or surpassed exercise in such things as improving balance, reducing fatigue, decreasing anxiety, cutting stress, lifting moods, improving sleep, reducing pain, lowering cholesterol, and more generally in raising the quality of life for yogis, both socially and on the job. The benefits were similar to those that had surprised the Duke team.
    In summary, the specialists reported that yoga excelled in dozens of examined areas.
    But the scientists also spoke of a conspicuous limitation for an activity that had long billed itself as a path to physical superiority. The authors noted that the benefits ran through all the categories—“except those involving physical fitness.”
    For the world of science, the issue seemed to be settled. But for the world at large? In truth, all the labors and analyses got