February 4, 2010

Yoga's Effects Revealed

Long-time yoga practitioners have far lower levels of two by-products of stress and inflammation: IL-6 and CRP.

Many studies have shown that practicing yoga translates into health benefits. One benefit is yoga's ability to lower stress. Exactly how yoga does this is something of a mystery. A team at Ohio State University set out to measure what changes occur in the blood when people practice yoga.

They didn't find exactly what they were looking for. They did find that long−time yoga practitioners entered the study with lower blood levels of compounds known to promote inflammation. They also found that during the study, stressful activity caused less of a rise of one of these compounds in long−time practitioners than in novices.

Yoga yields its secrets slowly.

The researchers were expecting to see many physiological changes caused by the yoga session and also differences in the responses of novices and experts. They didn't see this.

The most striking finding of the study was that veteran yoga practitioners arrived with a 41% lower blood level of the compound interleukin−6 (IL−6) than the novices did. The body produces IL−6 as part of its general inflammatory response, and high IL−6 has been implicated in heart disease, diabetes and a number of other diseases. Long−time practitioners were also five times less likely to have detectable levels of C−reactive protein (CRP) in their blood, a protein that is an indicator of inflammation.

Stress often leads to heightened inflammation. The implication of the study findings is that people who practice yoga are physically better able to handle the stress that occurs in their life.

The study was of 50 women of average age 41. They were divided into two groups: novices, who had previously participated in 6−12 yoga sessions and experts who had practiced yoga one or two times weekly for at least two years and at least twice weekly for the last year. Participants were fitted with catheters in one arm so blood samples could be taken during the study. They then performed several stressful tasks, including immersing a foot in extremely cold water for one minute followed by performing difficult mathematical calculations without pen or pencil. Afterwards, they would either participate in a yoga session, walk on a treadmill set at the slow pace of 0.5 miles per hour (to simulate the exercise involved in the yoga session) or watch videos.

The researchers were expecting to see many physiological changes caused by the yoga session and also differences in the responses of novices and experts. They didn't see this. One possible reason is that the yoga poses chosen were very simple, poses that novices could perform as well as the experts. They did see that the novices' IL−6 levels rose more in response to the stressful activities than the experts' levels did.

Because there are so many facets to yoga, it is difficult to sort out what specifically makes it effective in reducing stress. The exercise, the breathing, the emphasis on unity of mind and body, and other components may all play a part. Investigations into how yoga works are fairly new and designing meaningful studies is quite challenging to researchers. This study suggests that yoga helps dampen the body's general inflammatory response to the stresses of everyday living. In the long run, knowing that yoga does help people cope with stress is probably a lot more useful than knowing exactly how it does this.

An article detailing the study was published in an early online version on January 11, 2010 by the journal Psychosomatic Medicine.

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