Yoga may reduce stress by reducing baseline levels of inflammation and reducing inflammatory responses to stressors.
Do yoga and your body
- Starts with less stress (via less inflammation)
- Reacts with less inflammation (meaning less stress)
Sensationalism aside, a new research study showed that these may be benefits of yoga.
The new research paper titled “Stress, Inflammation, and Yoga Practice” by Janice Kiecolt-Glaser, Lisa Christian, Ronald Glaser and fellow researchers at Ohio State University appeared in Psychosomatic Medicine January 2010.
The researchers took a look at inflammation by examining cardiovascular, inflammatory and endocrine responses of new and experienced yoga practitioners. They also tested signs of stress and inflammation before, during, and after the students did yoga vs. control tasks (walking and TV watching).
Why care about inflammation and stress?
When it comes to aging, stress and the inflammation it causes are the body’s mortal enemy. Inflammation is a known to play a role and a risk factor in diseases as varied as heart disease, strokes, arthritis, osteoporosis, gastrointestinal conditions, Alzheimer’s disease, arthritis, heart disease, allergies, Type II diabetes, many auto-immune diseases, periodontal disease, and frailty and functional decline. In addition, inflammation is now regarded as a risk factor for most cancers because of the evidence that inflammation influences tumor promotion, survival, proliferation, invasion, angiogenesis, and metastases. (Kiecolt-Glaser, 2010. p.1) ¹.
Even obesity is characterized by a state of chronic low-level inflammation. Chronic inflammation messes with the critical relationship between immunity and metabolism. (Inflammation, stress, and diabetes. (Wellen 2005.) ²
Stress causes inflammation. Stress comes in many forms including emotional and physical. [Emotions actually have a physical and whole body process, but that’s for another post.] Emotional and physical stressors activate immune and endocrine pathways that can enhance inflammatory molecules (pro-inflammatory cytokines).
Stress really is killing us.
Since inflammation is killing us, it would be useful to look at interventions (like yoga) that could reduce our levels of inflammation. If we can minimize the autonomic and inflammatory responses to stressful encounters then we reduce the total burden of stress on the body.
This newest study shows that experienced yoga practitioners begin with a lower baseline level of inflammatory molecules, and produce less of those inflammatory molecules in response to stress.
In fact, the same inflammatory molecules that are found at higher levels in obesity were found in lower levels amongst experienced yoga practitioners.
Since reducing inflammation may provide substantial short- and long-term health benefits, effective interventions such as yoga should become part of the standard of care. Preventative medicine becomes a key solution to our health care crisis. One of the study’s authors, William Malarkey, MD stated, “People need to be educated about this. They need to be taking responsibility for their health and how they live. Doing yoga and similar activities can make a difference.” (Science Daily) ³
I have a great interest in encouraging transparency and the free flow of information with regard to yoga research. Many times I find myself reading a summary of a new study or “finding” and wanting more than just the take away sound bite. I want to know who was part of the study, how methodical it was, what was measured, what kind of yoga they did, etc.
So this time, I did some digging around to find more details. The breakdown that follows is my own work and done in the spirit of creating openness and appreciation around clinical research being done.
I hope the following study breakdown provides useful information for yoga teachers, yoga students, and research nerds like myself
Yoga Research Study: Design and Goals
The study was designed to measure the power of yoga to promote recovery after a stressor. The study was designed so that the stressful event occurred before the yoga session (the intervention). In this manner, the researchers could look at two questions:
1) Does yoga speed up the bodies’ recovery from a stressor? =
Compare yoga and other activities.
Here we ask whether yoga worked relatively immediately, like a drug, and promoted recovery from the stressor. This would be like giving Tylenol to a sick child with a rising fever–the drug changes the body chemistry and results in a lower fever.
2) Does regular yoga improve the bodies’ ability to withstand stressors? =
Compare novice and expert yoga students.
Here we ask if the research subjects who had more yoga experience before the study (yoga “experts”) actually reacted to the stressor differently in the first place. Perhaps regular yoga practice had changed the way students’ bodies reacted to stress down at the level of chemicals in the body.
Who were the research subjects?
50 healthy women (mean age, 41.32 years; range, 30 – 65 years). Primarily white; all with some college education. 14 women were post-menopausal.
Classified into two groups:
- 25 “Novices” who had participated in yoga classes or home practice with yoga videos for 6 to 12 sessions.
- 25 “Experts” who had practiced yoga regularly one to two times per week (75–90 minutes sessions) for at least 2 years, and at least two times per week for the past year.
For a total of 50 women.
Notes: Women who were classified as “intermediate level” were not included in the study.
What were the stressors?
- “Emotional Stroop” test. In the regular Stroop test, someone is asked to name the color of a printed words. The printed word could actually be the color as in red green blue yellow green red blue or the color could conflict with the word as in green red yellow blue red yellow green. The greater difficulty in naming the second set of colors is known as the Stroop effect. The point of interest is your difference in difficulty. The researchers in this study used an emotional Stroop. Here the participants named the colors in which negative or threatening words were printed. The words fell into anxiety- and depression-relevant negative words, positive words, and neutral household words.
- Cold pressor: one foot into warm water, then icy cold water for a minute. Purpose: essentially a down and dirty way to get some mild pain and provoke an endocrine and inflammatory response in the body.
- Mental arithmetic of progressing difficulty for 5 minutes.
What was the yoga session? The intervention (what was the “drug” being researched)? The controls?
- a restorative hatha yoga session in the Iyengar tradition [Check back for the poses and sequence. I will post later. If you want them sooner, let me know.]
- Movement-control: Walking on a treadmill at 0.5 mile per hour plus resting supine (because best approximated the heart rates during the restorative yoga session).
- Passive-control: a neutral video without any music (included segments on quantum physics and chemistry and teaching high school physics).
Experimental design resulted in an overall mean heart rate for yoga that did not differ from the movement control.
How long was data collected?
Over 3 years.
When was the testing done?
The subjects were tested before, during, and after a restorative hatha yoga session, as well as in two control conditions (walking and TV watching).
Each participant had a yoga session, a walking session, and a TV session. Sessions were at held at least 2 weeks apart. The order of sessions was random.
What was tested?
The researches intended to study yoga’s effect on inflammation by examining inflammatory and endocrine responses.
The researchers took a look at self-reported measures of nutrition, sleep, and mood. In the lab they tested
- Inflammatory, and
- Endocrine responses.
The researchers measured things like abdominal fat (to look at obesity), oxygen consumption via V02-max (to look at cardiopulmonary endurance and heart health), skin barrier repair–“a stress-sensitive process modulated by both cortisol and cytokine production” (Kiecolt-Glaser, p.2), blood levels of cortisol, catecholamines, and six pro-inflammatory cytokines (more info below). The point is less memorizing what they measured, but to recognize the wide swath of measures the researchers took. Ultimately only a couple of their measures gave interesting differences between novice and expert yogis and between yoga and non-yoga sessions.
The women were stressed before their yoga (or walking or video) sessions. The researchers looked at changes in their self-reported measures and lab tests.
What were the results?
Many of the measures and tests resulted in no statistical difference between experts and novices, and between the yoga and non-yoga interventions.
A few interesting things to pull out:
Positive affect increased in participants after they had their yoga sessions. Translation: yoga improves people’s mood. Yoga makes you feel good.
On the surface, no difference between novices and experts–both slept the same number of hours the night before their sessions. But when the researchers controlled for previous night’s sleep, the experts actually slept significantly more hours of sleep than novices on the night following their 6-hour-testing days. This provides interesting fodder and food for thought. Why would yogis require more sleep? Maybe they were able to relax more easily that night?
Significant effects for time and condition and interaction between time and yoga expertise
Experts had statistically significant lower heart rates than novices during the stressor (not including Stroop). At other test points, heart rates were similar. Remember that the emotional Stroop with the negative words occurred before the feet in cold water and math problems? Both novice and experienced yogis increased heart rate for the Stroop test and increased their heart rate even more for the cold feet and math stressors. Interestingly, the novices’ heart rates jumped significantly more than the experts.
The blood levels of several pro-inflammatory cytokines were measured. All those cytokines measured showed the hypothesized difference between experts and novices–with lower levels of inflammation in yoga experts compared with yoga novices. However, only IL-6 (on wikipedia) serum levels showed a statistically significant difference.
The yoga novices also produced significantly more Il-6 after the stressors compared with the yoga experts.
Cytokines are signaling molecules helping cells communicate information. In this case, IL-6 is part of the immune response. This cytokine of interest communicate trauma and helps arouse an inflammatory response from other cells.
This is the cytokine that you’ll hear about in the news and fanfare that “yoga reduces inflammation“. At baseline, novice yoga students had levels of IL-6 levels were 41% higher than experts.
To be clear:
- Experts had a lower overall IL-6 serum level baseline than novices.
- Experts produced less IL-6 in response to the stressors
In addition to Il-6, other statistical analysis supports the finding that more yoga experts have a lower baseline for all six inflammatory markers tested. That is as baseline (before stress):
- Most yoga novices produce more inflammatory markers.
- Yoga experts produce less inflammatory markers compared to novices.
This is a positive answer to the second question posed under study design:
2) Does regular yoga improve the bodies’ ability to withstand stressors? = Compare novice and expert yoga students.
1) Does yoga speed up the bodies’ recovery from a stressor? = Compare yoga and other activities.
No, at least not according to this study.
Yoga sessions improved participants affect (mood), but the researchers did not find differences in inflammatory or endocrine responses that were unique to the yoga session. That means there was no difference between yoga, walking or video sessions on these measures. (The researchers note a limitation of their study: that the mild stressor and gentle nature of the yoga may not have been the best test of yoga’s immediate “drug-like” benefits.)
Whew. Seems like a lot of work, time, planning, and study designing to get this one positive, statistically significant result.
But that’s how this modern western scientific method works today. Big changes happen in small, incremental steps–studies build on studies, which build on studies. A study comes out, it declares proof that the world is not flat but round, and then everyone goes back to their labs or their clinics and tries to replicate the result. If other labs can replicate those results, and build on them, you have a winner. If the results aren’t replicable, it’s a dud, fading into obscurity.
Some very important ideas and discoveries have come out of this system. But to the person living today who wants to take action, it can all seem very slow. So it’s tempting to take these studies and take them as fact and declare: “see! yoga/acupuncture/meditation/aikido/running/swimming/flying-kites/flying-balloons/my-lifestyle cures/prevents EVERYTHING!”
Patience and all is coming.
This is a perfect time to step back, be smart, and be patient. That is not to say to ignore research or not apply its findings (this blog is quite the contrary to that!) Just that we should be mindful of how we may take a research’s findings as final and develop a whole life plan around it. Be smart.
But smile a bit to recognize that the PhD’s are catching up with what you intuitively know:
Yoga affects the whole body and mind.
The science is just beginning to tease out a few of yoga’s effects and benefits.
I hope the above study breakdown gives more insight into the process and thought of study design and their results. My goal is that we can begin to think critically about studies–to evaluate, to understand, and to use their results. A critical eye tuned to research gives us knowledge we can put into practice.
Thanks for making it though this LONG post. (If this was useful to you, let me know. I may do some versions in the future.)
As always your feedback appreciated. I welcome more questions about the study methods, results, my interpretation, or your ideas about applications. Also I welcome feedback if you find any errors—factual, logical, or otherwise. Please let me know in the comments below.
References and further exploration
- Pubmed Abstract Stress, Inflammation, and Yoga Practice.
- Breakdown and study design sourced from original paper: Kiecolt-Glaser JK, Christian L, Preston H, Houts CR, Malarkey WB, Emery CF, Glaser R. Stress, Inflammation, and Yoga Practice. Psychosomatic Medicine. 2010 Jan 11. Footnoted 
- Biography of lead author Janice Kiecolt-Glaser
- William Malarkey, coauthor quotes from Science Daily release “Yoga Reduces Cytokine Levels Known to Promote Inflammation, Study Shows.” ScienceDaily 14 January 2010. (Retrieved 01/18/2010) Footnoted 
- Pubmed Abstract: Wellen KE, Hotamisligil GS. Inflammation, stress, and diabetes. J Clin Invest. 2005 May;115(5):1111-9. Review. PubMed PMID: 15864338; PubMed Central PMCID: PMC1087185.
Further discussion on the connection between obesity and metabolic diseases (including Diabetes) and chronic inflammation, the full paper Inflammation, stress, and diabetes (PDF) along with others can be found here at the Hotamisligil Laboratory: Inflammation, Stress and Metabolic Diseases at the Harvard School of Public Health. With papers in Nature, Science, and Cell, this lab is the real deal. Highly recommend a perusal through the full paper, parts are more readable than the lab page. Also check out their Inflammation and Metabolic Disorders (Abstract | PDF). This was a review in Nature 2006. Little chemistry, more narrative, cool figures, concepts, evolution, the lay of the land, future therapeutics. Even more highly recommended. Footnoted 
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