Yoga offers some obvious benefits: stress reduction, muscular flexibility, an enhanced sense of well-being, even cute clothes. But does it qualify as an aerobic workout?
Aerobic activity, characterized by an elevated heart rate and increase in the body’s use of oxygen, is closely linked to improved health and prolonged life spans; current guidelines suggest that people get at least 150 minutes of moderate aerobic exercise each week. Scant research has examined whether yoga is exercise under those guidelines, though. Now two new studies in Complementary Therapies in Medicine indicate that it can be, at least if it’s done rapidly.
The practice of yoga in America typically consists of bodily poses interspersed with or followed by breathing exercises and meditation. The most famous movements are incorporated into the sun salutation, a series of poses that includes the downward-facing dog, among others. These are usually performed near the start of yoga classes and can be among their most physically demanding segments. Yet according to a 2016 review of yoga research, the energy expended by those who move slowly during sun salutations generally compares to the demands of a stroll at three miles per hour. (This was the case for both standard yoga and the poses used in Bikram-style hot yoga.)
Exercise scientists at the University of Miami wondered whether less-languid yoga would be more aerobically beneficial. They outfitted 22 healthy adult male and female volunteers with masks and sensors that measured energy expenditure and muscular activity and had them complete as many sun salutations as possible in eight minutes while taking either 12 seconds to hold and flow from pose to pose or three seconds. (The subjects had experience doing yoga.)
Not surprisingly, doing yoga faster required greater effort and burned far more calories: about 48 calories on average during the eight-minute sessions, compared with 29 calories while doing the standard salutations. But the researchers were intrigued to find that most of this exertion took place in between poses rather than during the poses themselves.
The salutations, particularly when done three times as fast, functioned as intense interval training, says Joseph Signorile, a professor at the University of Miami and the senior author of the studies. Transitioning from pose to pose was similar to sprinting, he says, while the poses allowed for brief recovery. Eight minutes of almost any type of high-intensity interval training qualifies as an aerobic workout.
Of course, most yoga classes are not structured as this experiment was. Those seeking physical exertion should look for classes billed as “power” yoga, according to Melanie Potiaumpai, who led both studies as a doctoral candidate in Dr. Signorile’s lab.
Dr. Signorile acknowledges yoga’s nonaerobic virtues. “We’re not saying that you should ignore the meditative side,” he says. The guided contemplation of body and self provides significant psychological benefits. But the energy expended to achieve those gains is about the same that you would spend taking a nap.