The Science of Yoga: The Risks and the Rewards (14 page)

It was, arguably, a small step for the recognition of yoga as an aerobic activity—a step grounded in the discipline’s growing incorporation of such vigorous poses as the Frog and the Sun Salutation. Or perhaps it was simply a fluke. The lack of experimental controls increased the chance of false readings.

Whatever the study’s scientific merit, the leaders of the yoga community, long on the defensive when it came to cardiovascular issues, seized on the modest
finding as a breakthrough. It was hard proof, they asserted, that yoga is all an individual needs to stay fit. The contention was a bold restatement of Gune’s early claims. Only now—in theory, at least—it had the steel of modern science.

A portrait of the aerobics research formed the heart of a 2002 article in
Yoga Journal.
The glossy magazine prides itself on giving readers “the most current scientific information available.” It spread its lengthy cover story on yoga fitness over nine pages and illustrated it with lots of color photographs of yogis in scientific labs undergoing close scrutiny. A main location for the documentary photos was the University of California at Davis. In its article,
Yoga Journal
reported that it had carefully surveyed the world of science and discovered solid evidence that “optimal fitness” requires no running or swimming to strengthen the heart and no weight lifting to build the muscles.

“Yoga is all you need,” it declared, “for a fit mind and body.”

The article said nothing about the downbeat findings of Cooper and the Duke scientists. It did, however, highlight the Davis study, calling the 7 percent rise “a very respectable increase” and hailing the aerobic finding as a breakthrough. Even so, the article, like the Davis authors, provided little context for the figure—making no comparison, for instance, to what endurance training can do for peak oxygenation.

Reaching further,
Yoga Journal
filled its article with profiles, testimonials, and anecdotal studies of people who hailed the yoga-alone perspective.

It quoted Dina Amsterdam. “I haven’t done anything but yoga and some hiking for ten years,” she said. “Yoga completely brought me back to physical and emotional health.”

The Davis and
Yoga Journal
articles quickly became the go-to authorities around the globe for demonstrating that yoga alone was vigorous enough to meet the aerobic recommendations. The door had opened a crack, and a blast of aggressive marketing shot through.

One of the flashiest promoters was YogaFit, a commercial style that originated in Los Angeles. Its founding goal was to make yoga an integral part of the fitness industry. The style combined push-ups, sit-ups, squats, and other repetitive exercises with traditional yoga postures in a flowing kind of Vinyasa format. A centerpiece was the Sun Salutation. Seeking a wide audience, the style hailed sweat over what it characterized as yogic mumbo-jumbo, focusing instead
on earthy rewards. For instance, its YogaButt program claimed to “totally transform your thighs and glutes,” resulting in a bottom that is “sleek and sexy.” YogaFit sold. Starting in the 1990s, its fast workouts spread through gyms, spas, and health clubs, with thousands of women taking up the contemporary hybrid. Its big hit was YogaButt. To satisfy demand, the company developed a course of training that could certify instructors in four hours.

YogaFit presented itself as a plunge into extreme fitness. Beth Shaw, its founder, claimed that the vigorous style focused minds, trimmed fat, toned bodies, and provided “a tough cardiovascular workout.” Her promotional literature, when enumerating the fitness benefits of the style, cited the number one payoff as “cardiovascular endurance.”

In 2003, the company sought to substantiate her cardio declarations. The sixteen-page paper, “Health Benefits of Hatha Yoga,” cited no lab studies that YogaFit had sponsored. Instead, it reviewed the existing research. The paper cited the Davis study, the
Yoga Journal
article, and other inquiries as demonstrating that the style offered a serious path to the heights of cardiovascular fitness.

As usual in such tellings, the paper ignored the negative findings and the context. Still, it made the best of a tenuous situation and called YogaFit and other energetic styles of yoga “aerobically challenging.”

The good news spread. It traveled far beyond the insular world of yoga into mainstream culture. There, amid the blur of health and beauty tips, it got promoted as a scientific insight—with all the weightiness that such a discovery implied.

In 2004,
Shape
, which calls itself the lifestyle magazine for the active woman, hailed the Davis findings as proving that yoga provided all the cardiovascular benefits that anyone could want. “You don’t need traditional cardio,” it assured its readers, which it put at more than six million. The attainment of this most challenging of fitness goals, the magazine added, requires “nothing more than a yoga mat.”

A principal dynamic in the psychology of scientific advance is the action–reaction cycle. Its workings are often on public display in the case of big claims, especially when the perception arises that the claimants have offered inadequate evidence to back up their declarations. At that point, the pendulum starts to
swing in the opposite direction and the organized skepticism of science takes over. Rivals seek to poke holes in the original claim and try to discredit the original arguments. At times, the resulting disputes get settled quickly. But sometimes they drag on for decades as each side seeks to assemble evidence weighty enough to settle the argument once and for all.

Yoga’s claims of aerobic excellence got caught up in that kind of reactive cycle. A large assertion had been made and had received considerable public notice—that yoga alone is sufficient to achieve cardiovascular fitness.

The claim was big and so were the stakes. If true, yoga could enter the pantheon of activities that global authorities had identified as vigorous enough to produce the array of cardio benefits—to raise stamina and lower the risk of heart disease, diabetes, cancer, and many other diseases.

From a business angle, the claim was pure gold. It could turn a simple form of exercise requiring no costly equipment or investment into a dazzling profit center. The pronouncement caught the attention not only of supporters but, increasingly, of skeptics.

The wave of scientific reaction started in 2005 even as the aerobic claims continued to echo and multiply through yogic and popular culture. It began at Texas State University. Carolyn C. Clay, a young scientist who practiced yoga, talked four colleagues into joining the investigation. Their study appeared in The
Journal of Strength and Conditioning Research
, the scientific forum of the National Strength and Conditioning Association, a nonprofit group of scientists and athletic professionals. The researchers looked at twenty-six women. That was more than twice as many subjects as in the Davis investigation. Moreover, the scientists examined the women not only as they did yoga but as they walked briskly on treadmills and rested in chairs. That gave the scientists a reasonable basis for comparison. It was an experimental control meant to enhance the reliability and—not inconsequentially—the credibility of their measurements.

Another precaution centered on skill. The scientists recruited volunteers from a university yoga class, and the subjects had practiced for at least a month. The experience factor implied that the moves and postures would be more precise and rigorous than with beginners, in theory strengthening the aerobic stimulus.
It bespoke an effort to take the measure of yoga as regular exercise.

Clay and her team also brought new precision to the measurement of oxygen intake. Unlike the before-and-after methods of the Duke and Davis studies, the Texas researchers fitted their subjects with face masks hooked up to breath analyzers, producing direct readings of respiration. The scientists judged that the gains in accuracy would outweigh any inconvenience.

The yoga session was shorter than in the Davis study. It lasted just a half hour, compared to an hour and a half. The scientists said they designed it to resemble a routine in a health club. The Texas study, like the Davis investigation, put Sun Salutations at the heart of the session.

The investigators cited the Davis paper in reviewing prior research. But their findings bore little resemblance. Perhaps most conspicuously, the Texas scientists explicitly addressed how their findings measured up to the official recommendations.

The team examined a variation of VO
₂
max known as maximum oxygen uptake reserve. It expresses the difference between oxygen consumption at peak levels of exercise and during rest. Since the resting metabolic rate of individuals can vary, exercise physiologists consider the reserve formula a more accurate way of making comparisons of athletic fitness. (The method is similar to how the vital index took personal factors into account.) The American College of Sports Medicine, in promoting aerobic conditioning, recommends that individuals draw on 50 to 85 percent of their maximum reserve. By contrast, the Texas scientists found that women walking briskly on the treadmill used about 45 percent.

And yoga? The women, while doing the routine, achieved far less—only 15 percent. The results, the scientists reported, “indicate that the metabolic intensity of hatha yoga is well below that required for improving cardiovascular health.”

The only encouraging news centered on the Sun Salutation. Clay and her team said the fluid pose turned out to represent the workout’s most aerobic aspect—a wide belief in the yoga community that had previously gone untested. The scientists found that Sun Salutations drew on 34 percent of the maximum reserve—more than twice the overall yoga session. And they suggested that the reading, though “significantly lower” than the 50 percent minimum of the American College of Sports Medicine, was nonetheless high enough
for yoga teachers to consider putting more emphasis on the vigorous pose.

“To increase intensity,” the researchers said, “it appears that the Sun Salutation or similar series of
asanas
should comprise the greatest portion of a Hatha yoga session.”

Another downbeat finding emerged in 2005, just a month later. The study was done at the University of Wisconsin. It centered on thirty-four women with no yoga experience and no history of regular exercise. The women were divided into yoga and control groups. The yogis did fifty-five minutes of Hatha three times a week for two months while the non-yoga group did no exercise at all. Compared to the Texas study, the workout was longer and presumably more vigorous.

The investigators in Wisconsin found gains in strength, endurance, balance, and flexibility. But not in VO
₂
max. “The intensity just wasn’t there,” noted John Porcari, one of the scientists.

The Wisconsin team did a companion study to see if Power Yoga—a demanding series of poses based on the Ashtanga system, with emphasis on flowing postures like the Sun Salutation—posed a greater aerobic challenge. The scientists recruited fifteen participants with at least intermediate experience. It turned out that the heightened vigor did make a difference, but only slightly. “You certainly sweat,” Porcari said. “But it’s not an aerobic workout.”

He disagreed with the Texans on the idea of introducing wide customizations meant to increase yoga’s vigor. Porcari said that adding more energetic postures as a way to boost cardio benefits would, by definition, come at the expense of flexibility, balance, and the other traditional benefits.

“It’s always a trade-off,” he said. “Yoga was designed for relaxation, primarily. The more aerobic you make yoga, the less improvement you’ll see in those other areas.”

Many yoga studies go unnoticed. The Wisconsin inquiry made waves, probably because its sponsor was the American Council on Exercise, a nonprofit group that seeks to protect consumers from risky and ineffective fitness programs. That gave the study added authority and exposure. The council, based in San Diego, published a digest of the Wisconsin study in its magazine and sent out a press release. The statement noted that the Wisconsin scientists
had found that each Hatha session burned just 144 calories—similar to a slow walk.

“Aerobics?”
The Washington Post
asked in its headline. “Not Among Yoga’s Strengths.”

Yoga Journal
took notice—defensively, acting like a true believer in denial. Its headline said it all: “Flexible
and
Fit.”

The magazine faulted the Wisconsin study, as well as the reaction of the news media, and went on to cite new evidence of yoga’s aerobic benefits. Once again, it found support at the University of California at Davis—the main source of its original good news on VO
₂
max some four years earlier. A Davis researcher,
Yoga Journal
reported, had studied four yoga instructors who displayed levels of fitness comparable to someone who jogged three or four times a week. The news media, the article insisted, had fallen for a misleading story and had missed an inspiring one.

But the new evidence was thin.
Yoga Journal
gave no details about the new Davis study, just the claims. And, as it turns out, the study was never published. Its existence amounted to a rumor, although the readers of
Yoga Journal
could be forgiven for thinking otherwise.

The more obvious problem was that the Davis scientist had drawn a comparison between extensive and small efforts—comparing teachers who did “several hours of yoga a day” to joggers who ran as little as three times a week. The finding implied that running was far more aerobic—just what an impartial observer might conclude.

“I think you just proved the point,” a reader wrote
Yoga Journal
in noting the lopsided comparison.

A final study, published in 2007, sought to settle the debate once and for all. It fairly breathed thoroughness and rigor. For instance, it did its recruiting in the studios of Manhattan, where youth, fierce competition, and starry clientele had resulted in challenging routines and gifted students—some of the best the planet had to offer. The sites ranged from downtown, to Midtown, to the Upper West Side. They included the torture chambers of Bikram Yoga (“we forge bodies and minds of steel”), the stylish removes of Levitate Yoga (“be free to wear the latest Louis Vuitton or Prada items”), and the sunny halls of the World Yoga Center (“created with a pioneering and idealistic spirit”).