The Science of Yoga

pursuing yoga for flexibility and its other rewards. They are known as cross trainers. Their diverse workouts complement one another to produce a balance of benefits.
    Cross training has no gurus, no schools, no fees, and no advocacy groups. Even so, it has a growing number of adherents, including top athletes. For instance, Alan Jaeger, a baseball pro with a passion for yoga, runs a school in Los Angeles for big-league pitchers. His stars run, stretch, meditate, listen to music, do yoga poses, and meditate again—doing that kind of routine for hours before getting around to throwing a ball.
    The popularity of cross training serves as an instructive counterpoint to yoga’s overstated fitness claims. It speaks to the wisdom of people who pay close attention to what their bodies tell them tell them—and to the recommendations of public health officials.
    The guidelines for aerobic exercise developed slowly over the course of the twentieth century, as we have seen. Ultimately, the enterprise drew on the work of hundreds of scientists. A less conspicuous effort got under way during the same period. It focused not on the straightforward goal of quantifying oxygen uptake and determining its role in physical fitness but on the more difficult and amorphous problem of understanding how changing situations can shape human emotion.
    By nature, the moodquestion was far more challenging than studying the ups and downs of VO 2 max. An added complication was that the investigation of human feeling had less political traction because it involved fewer scientists, received less funding, and had less institutional support than was the case with research into sports and physical training. The pool of candidates shrank further still when the focus was on such curiosities as yoga. The discoveries in that case could be quite serendipitous in nature, as with the Duke investigators.
    Scattered groups of scientists nonetheless made notable progress in the course of the twentieth century. In recent years, their work has become more abundant and substantial. The field—after an early history of false starts and digressions—now appears to be coming into its own.
    The trend is significant. In the end, it may elucidate one of yoga’s most important benefits.

II
FIT PERFECTION
    I once took a yoga class where the male teacher held up an illustration of a muscular man and proceeded to ridicule the build as childish. His message was loud and clear—yoga produces a better physique and is more advanced than other varieties of body development. The class nodded in agreement. We were all in the same boat headed for the same destination—a place of lithe contours and sculpted abs, a land where physical fitness can reach astonishing new heights.
    Of course many yoga teachers honor the field’s spiritual roots with attitudes of humility. Some acknowledge that yoga has its own strengths and limitations. Even so, a number of gurus and teachers have put forth extraordinary lists of particulars to explain why yoga constitutes the ultimate form of exercise.
    Consider Bikram Choudhury, the founder of hot yoga, a man famous in the yoga community for his collections of Rolexes and Rolls-Royces. His brand is so popular and uniform that some call it McYoga. He demands that every studio do exactly the same sequence of twenty-six poses and two breathing exercises.
    Choudhury grew up in impoverished Calcutta but struck it rich in the United States, opening many hundreds of yoga centers. Uniquely, the exercise room of a Bikram studio is heated to a sweltering 105 degrees Fahrenheit (not unlike Calcutta on a summer day). Gleefully, Choudhury calls it his torture chamber—and indeed, beginners who enter the mirrored halls often experience spells of dizziness and nausea. Some pass out. The underlying theory seems to be that heat loosens the joints, muscles, and tendons and helps intermediate students push themselves hard, giving them a gratifying sense of progress.
    “So many Americans,” Choudhury scolds in his book Bikram Yoga , “ruin their bodies by blindly running around ‘exercising’ and playing sports. I tell mystudents, ‘No barbells, no dumbbells, no racket.’ Games are okay for children, for recreation and to teach them sportsmanship. But after that, you must give up trying to put a little round ball in a hole all the time.”
    In great detail, Choudhury explains why his yoga is superior to every other type of physical workout and why it