Today, we look at the effect yoga may or may not have on a wide variety of conditions, and…yes, I do a little myth-busting in both directions.
The practice of yoga for health has become popular in the United States and worldwide. A 2016 survey estimated that 36 million Americans may be involved in yoga to varying degrees. Though the origins of yoga go back thousands of years, it was only introduced to the United States about a century ago. What are the risks and the benefits?
Yoga users tend to report having a better health status, but that doesn’t necessarily mean yoga was the cause. For example, yoga practitioners were more likely to be normal weight rather than obese, and that alone could give you better health. Of course, if the yoga was responsible for the weight loss, then that would be to yoga’s credit. But yoga users are also more likely to be white, female, young, and college-educated—all of which are independently associated with better health status. The same thing with higher socioeconomic status.
Yoga practitioners also tend to exhibit other positive health behaviors––specifically more regular physical activity in general and a vegetarian diet. And the more yoga people practiced, the more likely they were to cut out meat and to eat more and more fruits and vegetables. For every additional day per week of yoga practice, the odds of being vegetarian increased 20 percent. About one in three yoga teachers surveyed in the UK follow a plant-based diet––much higher than the general population.
So, when you’re doing a study like this, comparing the cardiovascular health of yoga practitioners to runners, to sedentary individuals, you can see how difficult it would be to tease out the effects of yoga when significantly more yogis reported refraining from eating meat compared to the other two groups. It’s like when I was reading about the role of yoga in the prevention and management of various cardiovascular diseases, I was so excited to read that yoga could significantly reduce cholesterol levels. After all, heart disease is the #1 killer of men and women. And when I looked up those studies, I got really excited. Reversal of coronary atherosclerosis with yoga? I thought the only lifestyle intervention that could reliably do that was a whole food plant-based diet. Well, what do you think the Yoga Lifestyle Intervention was? A diet packed so full of whole plant foods—fruits, vegetables, whole grains, beans, and nuts—they were getting about 50 grams of fiber a day. No wonder they got heart disease reversal. But what role, if any, did the yoga itself actually play?
Now, if yoga gets you to adopt a better lifestyle—stop smoking, eat healthier—great. Whatever gets people to take better care of themselves. If your tinfoil hat tells you Martians want you to skip the doughnuts, I’m all in favor. Whatever it takes. But if we are to tease out whether practicing yoga has any special benefits in and of itself, we really need to look to interventional studies, randomized controlled trials that go beyond just associations and correlations, and can instead prove cause and effect.
For example, when we find yoga users have better health status, and are less likely to be obese, that could be reverse causation––meaning instead of yoga leading to better health and a normal weight, maybe being in better health, not being obese, is leading to more yoga. Same with the flipside. When you read that yoga practitioners are more likely to have mental health conditions—depression, anxiety—musculoskeletal conditions, like arthritis, gout, lupus, fibromyalgia, joint pain, sprains, and asthma, yeah, maybe yoga could be contributing to some of these conditions, like muscle sprains, but for most of these, it’s probably reverse causation—people with diseases seeking help. Are they getting it? The only way to know for sure, is to put it to the test, which we’ll explore, next.
Yoga is practiced by millions of Americans, and is often recommended as therapy for a variety of medical conditions. But does it work, and for what? In my last video, I talked about how yoga practitioners tend to report better health status. But they also tend to be wealthier, and confounding factors like that make it hard to draw claims about yoga efficacy. For example, when population studies have taken factors like education or income into account, the yoga effects often evaporate. You can’t really tell if something is good or bad until you put it to the test.
Unfortunately, only about a quarter of the published studies examining the effects yoga on health or well-being outcomes were randomized controlled trials, and of those, half compared yoga to basically just doing nothing. And in that case, if you find a benefit, you don’t know if it’s the yoga itself, or whether any kind of exercise would have achieved the same or even better effect. Now look, any kind of physical activity is good, but is there more to yoga than exercise? For example, any kind of exercise, whether low intensity, such as yoga, or high intensity, such as aerobics, may help with menstrual pain––compared to not doing anything. In studies on alcoholics, aerobic exercise alleviated depression and anxiety symptoms more than yoga––presumably just because of the greater exercise intensity.
Typical yoga is probably best described as a light intensity physical activity. For example, here’s the metabolic equivalents of some typical yoga poses. The average maybe two or three. Compare that to walking at a typical speed, which is about three. So, in general, walking burns about as many calories as yoga, and brisk walking would burn even more. There’s all sorts of crazy claims about how so-called “hot” yoga expends up to like 1,000 calories. But no, you burn about the same calories at room temperature. So, 90 minutes would just be more like 300 calories. But isn’t yoga so much more than just a workout? Let’s see how the data pan out.
Multiple sclerosis, for example. We know that exercise can be beneficial in many health conditions, including neurological disorders. And it may not be surprising that yoga, which involves a series of poses, postures, movements, and breathing patterns that could improve balance, muscle strength, and flexibility, should be found beneficial to patients with, say, multiple sclerosis. Let’s see if that’s actually true. No benefit for overall quality of life, or physical quality of life, or psychological quality of life. Also, no benefit for sexual function or cognitive function. And this was all comparing yoga to doing nothing. A similar failure to find much improvement in quality of life for people living with chronic diseases in general was noted, with only one in seven trials finding a clinically significant benefit. Researchers did find yoga helped fatigue in patients with MS, but not any better than regular exercise.
Same with chronic low back pain. Yoga might decrease pain and improve function, compared to not really doing anything, but had the same effect on pain and disability as any other exercise or physical therapy. So, if you like yoga and want to make that your exercise of choice, great. But it doesn’t appear to have any unique benefits for back pain.
Same with insomnia. Yoga works compared to nothing, but not to physically active controls. And, for cancer patients—mostly breast cancer patients—walking was found to be more effective than yoga at improving sleep. For markers of systemic inflammation in breast cancer survivors, six months of yoga had the similar effect as six months of non-yoga exercise. Same with cancer-related fatigue and quality of life for women with breast cancer––better than nothing, but no better than other types of physical activity. Finally, for breast cancer survivors, the effectiveness of yoga Interventions in breast cancer-related lymphedema, an abnormal accumulation of fluid for which there is no effective treatment, and adding yoga does not seem to help.
There are some conditions for which yoga really does appear to pull ahead of the pack, though. For example, chronic nonspecific neck pain. Based on 10 randomized controlled trials, not only was yoga better for neck pain than control groups in general––which included doing nothing, yoga also seemed to beat out active controls, other types of exercises. The authors tentatively conclude that yoga can relieve neck pain intensity, improve pain-related disability, increase range of motion, improve quality of life, and boost mood among neck pain sufferers.
Finally, today, what happens when real yoga is compared to sham yoga?
Yoga is an ancient mind-body discipline which originated in India thousands of years ago, and that’s where most yoga studies are done to this day. This has raised concerns that national pride might incline Indian researchers to quietly shelve any negative results and just publish studies showing yoga works. This fear is not without precedent. For example, research conducted in China, Japan, Hong Kong, and Taiwan was found to be uniformly favorable to acupuncture; all trials, without exception, were positive. Now, one possible explanation for this finding is that acupuncture is just more effective in countries where it is traditionally practiced. But it is a little suspicious. So, are Indian yoga trials more likely to be positive than those from other countries? They looked at hundreds of randomized controlled trials of yoga, both done in India and done in other countries, and trials on yoga conducted in India had about 25 times the odds of reaching positive conclusions as those conducted elsewhere. Again, yes; yoga might be more effective in India than elsewhere, but it is a little suspicious.
So, for example, if you’re interested in whether yoga is helpful for treating headaches, and you read that yoga appears to be helpful for those suffering from tension-type headaches. But then you find out that nearly all such studies were conducted in India, what do you do with that information? Also, notably, none of the control groups had any sort of exercise component, though this may be less critical for tension headaches, since neither aerobic exercise training…nor strength training appears to help them. So, if we’re to believe the Indian study conclusions, yoga may indeed help with tension headaches, but even they found no effect for migraines. What may help migraines, though, is other types of exercise––specifically aerobic exercise, decreasing migraine pain intensity, frequency, and duration, at least in the short term.
What about the benefits of yoga practice compared to physical exercise in the management of type 2 diabetes? A significant reduction in both short-term and longer-term blood sugar control was noted in the yoga groups compared to other exercise control groups. However, the findings may need to be interpreted with caution, since nearly half of the studies didn’t define and adhere to a well-planned exercise regimen in the control group. Furthermore, an exercise intervention comparable in intensity to yoga was followed only in three out of the eight studies included. And, for what it’s worth, the majority of the studies, six out of eight, were from India.
When yoga was carefully compared to sham yoga, which consisted of chair exercises, standing exercises, and slow walking to match the yoga session, the relative yoga benefits evaporated. Both yoga and sham yoga had identical effects on blood sugar status. Hence, further well-controlled randomized trials are required prior to drawing conclusions about the benefits of yoga in comparison to physical exercise in patients with diabetes.
Similar tentative conclusions were reached for yoga for osteoarthritis. Put all the studies together, and yoga may indeed be effective for improving pain, function, and stiffness in individuals with osteoarthritis of the knee––compared not only to doing nothing, but compared to other kinds of exercise. They had some issues with the quality of some of the studies, and so, only a weak recommendation for the use of yoga for osteoarthritis. But hey, if you like yoga, or if yoga is the only kind of exercise you’re willing to do, then it’s probably better than nothing.
Finally, in this video, let’s look at the effects of yoga compared to active and inactive controls—meaning like compared to other exercise regimens, or just like doing nothing—on physical function and health-related quality of life in adults aged 60 and older. Compared to doing nothing, they found clear evidence that yoga improves physical function and psychological wellbeing in older adults. So, definitely better than nothing. What about compared to other exercises? Yoga pulled ahead for lower limb strength and lower body flexibility, but for improving balance, mobility, and walking speed, yoga appeared comparable. Psychologically, yoga appeared to beat out other exercises for alleviating depression in older adults, but not anxiety or perceived mental health in general.
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