Benefits of yoga for physical fitness and overall wellness
What are the benefits of yoga for physical fitness?
A few years ago, researchers at the University of Nevada, Las Vegas, found that a brief yoga session allowed high school track athletes to improve their time for a one-mile run by an average margin of one second.
Not a particularly earth-shattering result—especially when you realize the same researchers also found that 20 minutes of motivational shouting (“You’re the definition of speed!”) improved performance by five seconds.
The point here is that it’s very difficult to tease apart the mental and physical components of athletic performance. That’s especially true for yoga, a word whose very meaning—“to yoke, or unite”—refers to the goal of integrating body, breath, and mind. “Yoga would say that there’s really no way to affect the mind without affecting the body, and there’s no way to affect the body without affecting the mind,” says Timothy McCall, a San Francisco doctor and author of the 2007 book Yoga as Medicine. Increasingly, though, people are turning to yoga in search of physical benefits. According to a 2008 survey, 15.8 million Americans were practicing yoga, and 49.4 percent of them started with the goal of improving their health (compared to just 5.6 percent in a similar survey five years earlier).
Considered strictly as a form of exercise, yoga has many strengths and a few key weaknesses. A 2001 study at the University of California, Davis, found that an eight-week program of two 90-minute hatha yoga classes per week led to significant increases in strength, muscular endurance, and flexibility. Other studies have found improvements in balance and even bone density. This is not really surprising—yoga is, after all, a weight-bearing physical activity. If you want to know how much you’ll improve, that’s a more difficult question, because there’s such a bewildering array of yoga styles. Like any other form of exercise, the benefits depend on which specific activities you do, how often you do them, and how vigorously.
A more controversial question is whether yoga is vigorous enough to count as aerobic exercise that improves cardiovascular fitness. While the UC-Davis study observed a small but measurable improvement of 6 percent in aerobic fitness, other studies have failed to confirm this. In a 2002 Northern Illinois University study of 45-minute “power” (ashtanga vinyasa) yoga sessions, the participants’ heart rates stayed below the recommended threshold for aerobic exercise. Similarly, a 2007 study found that average energy expenditure during a hatha yoga session was equivalent only to a leisurely stroll, although heart rates did reach a moderate level during the “sun salutations” portion of class.
That doesn’t mean yoga can’t provide a good aerobic stimulus. Karen Rzesutko, the lead researcher in the Northern Illinois study, says she believes an experienced power yoga practitioner “who is motivated enough to give 100 per cent to the practice” can reach and maintain a suitably high heart rate. But at a certain point, it’s probably best to accept yoga’s strengths and weaknesses rather than fight them, and seek your aerobic exercise in other ways. After all, McCall points out, having a balanced approach is a worthy yogic principle—that’s why he hikes, bikes, and dances in addition to doing yoga.
What are the benefits of yoga for overall wellness?
Of the eight “limbs” of classical yoga, formulated over 2,000 years ago, only one relates to physical fitness as we now think of it. The others include ethical principles, the flow of vital energy, and meditation as paths toward self-knowledge and enlightenment. These days, many people have a more casual attitude to yoga. But even if you just drop in to an occasional class, you’ll spend time on breathing and concentration exercises that you wouldn’t encounter in a typical gym routine—part of the discipline’s continuing commitment to a state of wellness defined much more broadly than the usual fitness markers.
Science, needless to say, seeks to classify and measure these benefits. One theory is that yoga helps to control the “fight-or-flight” response that physical, mental, or emotional stress triggers in your body. The stress hormone cortisol, for instance, triggers a cascade of physiologic, behavioral, and psychological effects through the endocrine system; similarly, your nervous system responds to stress by sending signals to elevate heart rate, blood viscosity, and blood pressure. If these responses are triggered too often, your body gets run down and susceptible to illness.
Several studies have found that yoga programs can lower levels of cortisol throughout the day, including a 2009 randomized trial that compared yoga with “supportive therapy” in a group of 88 breast cancer patients. (In contrast, yoga failed to change cortisol levels in another 2009 study of women with rheumatoid arthritis.) Various other studies have seen positive effects from yoga on outcomes like perceived stress, mood, and sleep patterns.
Of course, researchers have observed many of the same benefits from non-yogic exercise. A Rutgers University study in 2008 pitted hatha yoga against strength training in a head-to-head comparison, putting subjects through 50-minute sessions and then measuring the effects on anxiety, tension, calmness, and other mental health variables at 15-minute intervals afterwards. Both yoga and strength training had positive effects—yoga improved scores on anxiety and calmness, while resistance training improved all variables. Interestingly, yoga’s impact was most pronounced immediately afterwards, then began to fade within an hour. Strength training, in contrast, produced effects that intensified as recovery progressed, suggesting a longer-lasting result.
It’s important to note that the weights session was perceived by participants to be “moderate exercise,” while the yoga session was “light exercise”—a difference that could explain why weights had a bigger effect. But, lead author Joseph Pellegrino explains, the details of the sessions were carefully chosen to mimic how people really do weights and yoga, in order to do a real-world comparison.
Other studies have found, in general, more similarities than differences between yoga and other forms of exercise. A review of 81 studies by University of Maryland researchers in 2010 concluded that “yoga may be as effective as or better than exercise” for a variety of health-related outcomes but acknowledged a lack of rigorous studies.
For now, researchers haven’t been able to isolate and identify any secret ingredients that yoga offers and other forms of exercise don’t. But it’s clear that, whether you choose a yoga class or a relaxing bike ride along a waterfront path, you’ll be getting benefits for both body and mind.
CHEAT SHEET: FLEXIBILITY AND CORE STRENGTH
• Stretching increases your range of motion, but studies have failed to confirm that stretching reduces injuries. The best time to stretch for flexibility is after exercise, not before.
• “Static” stretching reduces strength, power, and speed for an hour or more, thanks to a combination of neuromuscular effects and lowered force transmission in “loose” muscles and tendons.
• Runners who display greater flexibility in a sit-and-reach test run less efficiently, and pre-run static stretching also lowers efficiency and worsens performance.
• Warming up with “dynamic” stretching exercises raises the temperature of muscles and prepares them for exertion but doesn’t decrease strength, power, speed, or endurance.
• Stretching after exercise makes no difference to how sore you are the next day.
• Hip muscles and deep abdominal muscles are more important than the superficial “six-pack” muscles for core stability and injury prevention.
• The benefits of yoga depend on the style and level; in general, yoga classes are good for flexibility and strength but are insufficient to count as an aerobic workout.
• Like other forms of exercise, yoga can help reduce stress hormones and control mood.