The results of the 2002 NHIS survey suggest that 5% of civilian non-institutionalized U.S. adults in 2002 used yoga for health, reflecting over 10 million yoga users.3
We found substantial differences in the use of yoga for health; users were more likely to be young, female, college educated, and white. While yoga users smoked less, they were more likely to drink alcohol. Yoga users tended to have a better health status and were more likely to be normal weight rather than obese. Yoga users were more likely to have mental health conditions (depression and anxiety), musculoskeletal conditions (arthritis, rheumatoid arthritis, gout, lupus, fibromyalgia, and joint pain), severe sprains and asthma, but less likely to have hypertension and COPD. A majority of yoga users reported yoga as important for maintaining their health, while a smaller number used yoga to treat specific conditions. Of those yoga users that practiced yoga for specific medical conditions, most used yoga for mental health and musculoskeletal conditions. Approximately 3 of 4 yoga users felt that yoga helped these two conditions. While most yoga users did not disclose their use to a medical professional, more than 1 in 5 reported that a medical professional recommended yoga for a specific condition.
Our results are similar to a previous report on yoga users based on a smaller nationally representative survey conducted in 1998.2
Although the methodologies of the two surveys differed, a higher prevalence of use is reported in 2002 of 5.1%3
compared to a rate of 3.7%2
in 1998. As with our analysis, yoga users in 1998 consisted mostly of well-educated, younger females. This prior study was limited by a sample size with 143 respondents who used yoga at least once in their lifetime, and 76 who used yoga within the last 12 months. Of those that used yoga at least once in a lifetime, lung disease was the only medical condition independently associated with increased yoga use. The results of our analysis based on a larger sample size of yoga users (n
1593), found asthma positively and COPD negatively associated with yoga use. A recent study has also identified that yoga users are less likely to be obese.4
A majority of yoga users identified yoga as being helpful for health maintenance. We also found that yoga users tended to report a higher health status as compared to non-yoga users. This suggests that yoga is being used mostly for health maintenance among healthier individuals. In mainstream media and culture, yoga is identified as a conventional form of exercise.5
As a form of aerobic exercise measured by metabolic equivalents, many forms of yoga may be categorized as low aerobic intensity.6,7
In this regard, yoga may have a potential role in patients with limited aerobic capacity or limitations that restrict use of conventional exercise. Given a growing prevalence of use and high perceived benefit for general well being, the potential mechanism and application of yoga for health requires rigorous evaluation.
Our findings suggest that patients with certain medical conditions, such as musculoskeletal, mental health, severe sprains, or asthma, are more likely to use yoga than the general population. Among yoga users, 16% reported using yoga to specifically treat musculoskeletal and mental conditions with yoga. Recently there has been increasing research on the use of yoga for specific medical conditions including those related to the musculoskeletal, psychiatric, cardiovascular, and respiratory system.8
However, many studies are methodologically flawed with absence of control groups, varying yoga interventions, poor definition of medical conditions and/or lack of allocation concealment.
Yoga has been studied for its efficacy in the treatment of musculoskeletal conditions including randomized controlled trials demonstrating potential benefit for lower back pain.9–12
A recent practice guideline, published jointly by the American College of Physicians and the American Pain Society, suggests yoga as a therapeutic option for patients with lower back pain that does not improve with self-care options.13
Yoga has shown potential benefit for other musculoskeletal conditions in the following studies: a randomized controlled trial (RCT) among patients with for osteoarthritis of the hand;14
an uncontrolled pilot among patients withosteoarthritis of the knee;15
a controlled trial for hand grip among patients with rheumatoid arthritis;16
an uncontrolled pilot for hyperkyphosis;17
and a RCT among patients with carpal tunnel syndrome.18
In addition, multiple randomized controlled trials have evaluated yoga for depression.19–22
All of these studies suggest benefit, but conclusions are limited based on heterogeneity of yoga interventions, depression severity, and subjects’ age, along with other methodological issues. Yoga may be beneficial for various anxiety disorders, especially obsessive compulsive disorders; however results are also preliminary and limited for similar reasons.23
Results of randomized controlled studies utilizing yoga for patients with asthma and COPD have been mixed. For asthma, studies have used various yoga interventions, including postures, meditation, and/or breathing exercises.24–30
Comparison of these studies is difficult because individual studies used different yoga protocols and clinical outcomes. A few studies suggest benefit of yoga use for patients with COPD.31–33
The cardiovascular yoga literature is growing with potential applications for patients with coronary artery disease, heart failure, and hypertension.34–36
Among subjects with hypertension, yoga interventions have demonstrated a benefit in seven of eight studies 37–43
with a single negative study.44
We found a negative association between yoga use and hypertension. This may suggest that yoga use lowers blood pressure. Alternatively, yoga users may be a select population less likely to have hypertension.
The decision to practice yoga for potential health benefits should be weighed against adverse effects. However, there are limited data on the potential adverse effects of yoga. Clinical trials of yoga lack adverse event reporting and few case reports are scattered through the literature.45–52
We report a positive association of musculoskeletal conditions and severe sprains with yoga use that may represent injuries secondary to yoga. Alternatively adults who practice yoga may be more prone to musculoskeletal conditions and/or sprains. Another possibility is that individuals who have these conditions utilize yoga for treatment or to prevent re-occurrence. We report a low disclosure rate of yoga use to medical physicians (25%). This parallels other complementary medical therapies (23–37%).53–56
In light of low disclosure rates and current literature, the actual frequencies or populations at risk for adverse events from yoga use remain unknown.
There are limitations to our study. Respondents self-reported all information; therefore the data may be subject to recall bias. Yoga users were defined by yoga use in the last 12 months, but the frequency of yoga use during this time period is unknown. Respondents were initially asked if they used yoga for health. There may be individuals who use yoga for personal or spiritual growth, rather than health, such that actual prevalence of yoga use may be higher. Given the cross-sectional survey design of NHIS, we cannot identify causal relationships between characteristics of yoga users and yoga use. For example, the lower likelihood of hypertension among yoga users does not necessarily mean that yoga lowers blood pressure. Lastly, our analysis from data collected in 2002 may not reflect current trends and characteristics of yoga users. Despite these limitations, this report represents the largest national survey of yoga use in the United States, and is the most detailed national portrayal of yoga use to date.
With ancient roots in India, yoga has evolved over two millennia from a discipline of mind and body for spiritual goals to a global practice aimed at maintaining physical health and psychological well being.57
Yoga, as a mind body practice, emphasizes mental discipline as much as physical, both synergistically intended to help with personal transformation. How this transformation may translate into health benefits has yet to be determined. We identified differences in yoga use among individuals based on demographic characteristics and health conditions. Future research should identify which populations are most likely to benefit from yoga practice. Research is necessary to determine which types of yoga are most beneficial for specific conditions, especially specific musculoskeletal and mental health conditions. Only more rigorous randomized clinical trials with large sample sizes will elucidate the potential therapeutic and preventive applications of yoga. With more than 10 million yoga users in the U.S., this line of inquiry will likely be of increasing interest to the medical community in years to come.