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Benefits of Yoga: Fact or Fiction?
By Cameron A. Roth
October 5, 2009
The practice of yoga can trace its roots back to Ancient India, where yoga was practiced as a ritual of meditation. Today, yoga is touted as a method to delay aging and guarantee a long, healthy life. There are many alternative medicines and therapeutic treatments being offered today, from acupuncture, herbal supplements and massage. Proponents of yoga claim that they are more relaxed, have a stronger immune system and spend lives their lives with a clearer mind. Here are the benefits listed on Nashville's #1 yoga studio, Hot Yoga Nashville's website (http://www.hotyoganashville.com/):
Accelerate Weight Loss
Increase Well Being
Improve Concentration & Focus
Develop Muscle Tone
Lower Blood Pressure
Improve Running Time
Lower Your Golf Handicap
Love Your Life!!!
These benefits sound fantastic, but are they actually true?
Another yoga studio in Texas advertises that “...you will be able to make real and lasting improvements to your health. This is achieved with a series of low impact breathing and stretching exercises, which work the body and focus the mind. After these exercises there is a relaxation period which calms the mind and body and helps to relieve stress.” (http://www.yogastudio.com/ )
One more Nashville studio claims that you will “Enjoy all the benefits of yoga. With even fifteen minutes of regular daily practice you can begin to feel your body, mind, and emotions all coming into harmony.” You'll become stronger, more flexible, more stress resistant - and you'll have fun doing it.” (http://www.yogacenternashville.com/yogacenter.htm#New To Yoga? )
Through rigorous research on the World Wide Web and scholarly journals, we will uncover the truth about the health benefits of yoga. More specifically, we will be looking at various peer-reviewed studies that address some mental and physical benefit claims of yoga practice.
What is Yoga?
The Merriam-Webster definition of yoga states that yoga is “a Hindu theistic philosophy teaching the suppression of all activity of body, mind, and will in order that the self may realize its distinction from them and attain liberation, a system of exercises for attaining bodily or mental control and well-being.” (http://www.merriam-webster.com/dictionary/yoga)
Hot Yoga Nashville defines it as “a scientifically designed series of postures, which systematically stimulates every muscle, organ, gland, as well as the entire nervous system to move freshly oxygenated blood to 100% of the body. These postures build stamina, flexibility, strength and balance and reduce stress. You will grow concentration, patience, and determination, and regain a calm and peaceful mind- the thing that matters most. All real health requires a calm and peaceful mind.” (http://www.hotyoganashville.com/) Yoga is essentially an Ancient Indian tradition that includes a practice of a series of postures that challenge the human body in terms of flexibility and concentration.
Yoga holds claims that it alleviates both mental and physical ailments. In total body function, yoga claims to “Massage all organs of the body” and engage the body in “complete detoxification.” (http://www.healthandyoga.com/index.html)
The usual #1 claim of yoga practice is the reduction of stress. “Yoga reduces the physical effects of stress on the body. By encouraging relaxation,yoga helps to lower the levels of the stress hormone cortisol. Related benefits include lowering blood pressure and heart rate, improving digestion and boosting the immune system as well as easing symptoms of conditions such as anxiety, depression, fatigue, asthma and insomnia.” (http://www.hotyoganashville.com/)
One of the most important physical aspects of yoga is the ability to learn to take deeper, slower breaths, which in turns lowers heart rate and blood pressure. “Yoga teaches people to take slower, deeper breaths. This helps to improve lung function, trigger the body’s relaxation response and increase the amount of oxygen available to the body.” (http://www.hotyoganashville.com/)
In this review, we will be looking at three case studies that look at both the mental and physical claims of yoga practice. First, we will analyze a study done in India that looks at yoga's antidepressant effects as compared to electroconvulsive therapy (ECT) and imipramine, an antidepressant pill. Secondly, we will also examine the physical part of yoga by looking at two studies that measure the effects of respiratory exercise on the body's metabolism and oxygen/carbon dioxide input/output of the lungs. Through this analysis, we will gain a deeper understanding of whether yoga has the potential to help relieve such mental and physical ailments.
Evaluation and Motives of Claims
The rationale behind excessive claims about yoga is probably very single-minded. Essentially, websites promoting yoga are selling a service. This service can be yoga classes or the sale of yoga products such as mats, towels, balls, etc. People are always looking for a quick fix, especially in this day and age of the ability to live longer and more prosperous. If a website claims that it can lower blood pressure, increase energy and increase metabolism just by doing some silly postures, many people will buy in. In addition, many yoga websites use arbitrary “buzz” words such as “cleansing” “catharsis” “positive impact” and “energy channeling”. All of these words sound mysterious and appealing. Yoga classes and gear can be extremely expensive. For example, Hot Yoga Nashville charges $109 a month for classes. In addition, most yoga studios also sell gear inside the studio in order to gain more profit. After all, the promotion of yoga is a business. We are going to find out if it is worth the money.
Is yoga an effective stress-reducer?
Everyday life contains a lot of stress, and people are always looking for an easy way to make themselves more relaxed. Too many stressors in life can lead to many mental illnesses, the main one being depression.
A study done in India in 2000 looked at the “Antidepressant efficacy of Sudarshan Kriya Yoga (SKY) in melancholia: a randomized comparison with electroconvulsive therapy (ECT) and imipramine.” Inclusion factors included a sample size of 45 (n=45) patients who were classified as melancholic depressive by the DSM-IV. The patients were subsequently randomized into three groups, one for yoga, one for ECT, and one for imipramine. For the patients in the yoga practice test group, they were trained in the practice of Sudarshan Kriya Yoga, a common yoga practice, by a trained individual from the Art-of-Living Foundation. After training, yoga was then practiced at least four days a week for 45 min at a time for four weeks. The ECT group received treatment three times a week, and the imipramine antidepressant pill group a 150 mg dosage nightly. Assessments were done by an unaffiliated psychiatrist. Measurements were done according to the Beck Depression Inventory (BDI) which is a 21 questions self report inventory that measures the severity of depression through a point system from 0-63. Point totals of 0-9 demonstrate no depression, 10-18 mild moderate depression, 19-29 moderate-severe depression and 30-63 severe depression. All of the patients exhibited moderate-severe depression.
The results of the experiment showed that all three groups experienced significant reductions in BDI scores, but there were no differences between them. Focusing on the yoga group, the mean BDI score from Week 0 – Week 4 dropped from 25.1+- 6.5 to 8.3 +- 8.6. Also documented was a 67% remission rate in depressive symptoms. The mean score of the yoga group was significantly higher than the ECT group (26.7 +- 5.0 to 2.5 +- 2.8) but comparable to the imipramine group (22.7 +-5.7 to 6.3 +- 7.9). This demonstrates that while yoga does have an overall reduction effect on depressive and stressful symptoms, electroconvulsive therapy seems like a better option in reducing unwanted symptoms.
Significance of Research/Critique of Methodology
This research clearly shows that yoga practice has a significant effect on reducing depressive symptoms. Unfortunately, the experiment does not name yoga as the best method in doing this, as ECT proved to be the most effective. Some critiques of the methodology are the small sample size and the subjectiveness of the BDI. First, the original sample size (n=45) and the group sample sizes (n=15 for all three) probably did not give enough representation, and in turn a larger sample size could have a provided use with a large statistical significance between treatments. A larger study would be able to see how much more effective ECT than yoga and imipramine, or if the treatments are as close as shown in this study. Secondly, the BDI is a 21 question subjective test that is given to the subject to rate their own personal feelings. Everyone feels differently about themselves, and it is really difficult to compare one person's thoughts of themselves to another. In addition, all of the test subjects were in depressive states, so that could have had an effect on their feelings towards the survey. Unfortunately, it is very difficult to quantitatively measure depressive symptoms without the input of the depressed individual.
Can breathing practice through yoga increase metabolism and lower heart rate?
As America looks to curb the obesity trend, metabolism and heart health are some of the hot topics being addressed. Metabolism is important because it addresses digestion and the distribution of essential nutrients throughout the body. Heart rate is also important because a lower heart rate is associated with a lower blood pressure and a healthier lifestyle.
Two studies address these topics. First, the “Cardiorespiratory and Metabolic Changes during Yoga Sessions: The Effects of Respiratory Exercises and Meditation Practices” conducted in 2008 in Brazil looked at the changes in cardiorespiratory and metabolic intensity through the practice of breathing exercises in yoga practice. Breathing and meditation are an essential part of the yoga practice. Inclusion criteria included nine yoga instructors (n=9) with a mean age of 44 +-11.6 years and a mean yoga experience time of 12.5+- 8.9 years. Measurements taken were the analysis of exhaled gases by a metabolic open circuit computerized system. In simple terms, a machine measured the oxygen uptake and carbon dioxide output through breaths of the individual. Three measurements stages were enacted: first, a measurement at rest, then during breathing exercises, and finally in meditation.
The results of the experiment showed a decrease in volume of oxygen uptake for the meditation period while there was an increase for the breathing exercises. For the meditation the volume of oxygen uptake in liters/min was .177 +- .004 as compared to .266 +- .10 for rest and .311 +- .14 for breathing. On the other hand, the results for oxygen uptake during breathing exercises was the highest. The research shows that during meditation, breathing slows down significantly. Tibetan monks who practice intense and extended meditation have been shown to have a 64% drop in metabolism. Slow breathing corroborates with heart rate, lower blood pressure and a more relaxed mental state. The research also shows that yoga breathing exercises increase metabolism significantly. This is important because this shows that yoga could be another method to help lose weight and establish a normal metabolic cycle.
The second study, “Hatha yoga: Improved vital capacity of college students” conducted in 1998 at a Midwestern university looked for a connection between excellent vital capacity of the lungs and yoga practice. 287 students (n=287), 89 men and 198 women enrolled in the study and participated in two 50 minute yoga classes a week for 15 weeks. Inclusion criteria included men and women with no known lung ailments along with a small sample size of smokers and asthmatics. A hand-held spirometer (device used to measure air inhaled and exhaled by lungs) measured the input and output of lung capacities of the students. All 287 students were instructed in correct yoga practice and breathing techniques before the experiment was conducted. Attendance was rigorously recorded to ensure reliability.
Results of the experiment demonstrated that many students, no matter lung-ailment or not, increased their vital capacity of their lungs over the research time frame. The average vital capacity for men before was 4551 mL and after was 5037 mL. Women also showed an increase; 3073 mL before and 3365 mL. The men's lung capacity is higher to start because biologically men have a larger lung capacity. In terms of groups, the no lung ailment group increased from 3504 mL to 3886 mL, while the smokers went from 3719 mL to 4045 mL and the asthmatics increased from 3485 mL to 3652 mL. It is interesting to note here that the smokers started out with the largest lung capacity even though their condition was the most chronic. This is not significant, but just an interesting side note. The differences in lung capacity due to lung conditions was not significant. The practice of yoga does show a benefit towards increasing lung capacity although it is tough to say whether the improvement is completely credited to the yoga practice.
Significance of Research/Critique of Methodology
Physically, it seems that yoga does have a beneficial effect on the body. These two studies demonstrated, although not completely, that yoga and breathing exercises during yoga practice do have a significant effect on the human body. Breathing exercises can increase metabolism, lower heart rate and increase lung capacity. Some critiques of the studies include the inability to pinpoint whether yoga was the sole reason for the physical improvement. Yoga is a lifestyle choice that usually is paired with healthier eating and feeling better about oneself. This trends itself towards a lifestyle change while practicing in yoga. It is possible that during these experiment time frames, lifestyle changes such as diets and more exercises were implemented in the individual's lives that added to the effect of the yoga practice. This would show up as an improvement in the quantitative tests, which is what was shown. Overall, the research did solely focus on yoga, and the results say that yoga is physically beneficial.
After careful analysis of three research studies and exhaustive research on the World Wide Web, it seems that yoga can be beneficial as a part of a healthy lifestyle that also includes a salubrious diet and good mental health. The research showed that yoga makes a difference in stress, depression, metabolism and breathing, but it does not back it up substantially enough to make excessive claims. From a personal standpoint, I have practiced yoga many times, and although I have no clinical evidence to prove anything, I just feel better, happier and stronger after every class. According to the data, yoga is a great way to continue an already hopefully healthy lifestyle, and can lead to a long and prosperous life.
Birkel, D.A., & Edgren, L. (2000). Hatha yoga: improved vital capacity of college students. Alternative Therapies in Health and Medicine, 6(6)
Danucalov, M.A., Simoes, R.S., Kozasa, E., & Leite, J.R. (2008). Cardiorespiratory and metabolic changes during yoga sessions: the effects of respiratory practices and meditation. Applie Pyschophysiology and Biofeedback, 33(2)
Janakiramaiah, N., Gangadhar, B.N., Naga Venkatesha Murthy, P.J., Harish, M.G., & Subbakrishna, D.K. (1999). Antidepressant efficacy of Sudarshan Kriya Yoga (SKY) in melancholia: a randomized comparison with electroconvulsive therapy (ECT) and imipramine. Journal of Affective Disorders, 57(1-3)
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