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COLUMBUS, Ohio – Conventional wisdom – and many an anecdote – suggest the stretching, balance and breathing associated with yoga practice provides benefits for the body and mind. But Ohio State University medical researchers are the first to put science behind the popular belief in those benefits by conducting a study to test yoga’s effect on stress in women.

“Everyone thinks yoga has health benefits, but a look at the literature shows we just don’t have good evidence proving those benefits exist,” said Janice Kiecolt-Glaser, director of the division of health psychology in The Ohio State University College of Medicine and principal investigator on the study. “That’s what this study is about – to see if we can find that evidence.”

The recently launched study is the latest by scientists in Ohio State’s Institute for Behavioral Medicine Research, whose body of work has provided compelling examples of the mind-body connection, most notably how stress can slow wound healing.

Why investigate yoga? Because, institute director and study investigator Ronald Glaser says, “If we can say a simple behavioral intervention such as yoga could reduce levels of stress hormones, that could have implications for reducing the risk for many diseases.”

The study is designed to compare how experienced yoga practitioners and those new to the practice respond to a variety of stressors. The researchers are beginning with the assumption that more experienced yoga practitioners will enter the study with lower baseline levels of stress hormones and be able to return to their baseline more quickly, all because they have a history of yoga practice to draw on as their bodies respond to stress imposed as part of the research, said investigator Dr. William Malarkey, an endocrinologist at OSU Medical Center and a longtime yoga practitioner.

The research team will zero in on immune and endocrine responses, running a battery of measurements on each individual to assess changes in proinflammatory cytokines, which aid the immune response and healing but cause trouble in the bloodstream if they’re elevated for too long; the release and regulation of stress-related hormones such as cortisol and adrenaline, which at prolonged high concentrations can disrupt a number of the body’s systems; blood pressure and heart rate; the ability of the skin to repair minor irritation; and mood.

Each of the 50 women between ages 35 and 65 – 25 experienced yogis and 25 novices – will be subjected to stressors before three daylong sessions during which their responses are measured. One session will involve the practice of hatha yoga restorative or immunity-enhancing postures. One control session will involve mild exercise designed to match the yoga’s metabolic demands, and a second control session will involve neutral activity with no movement. The stressors include a mental arithmetic test and dipping research participants’ feet into ice water, which prompts physiological stress.

The research will provide data about physiological changes over time by timing blood draws for each assessment before, during and after the performance of the yoga postures and the control activities.

“We are able to keep a catheter in the arm to take these blood draws at key points in the action to see exactly how and when stress hormones are changing,” Kiecolt-Glaser said. “What we’re hoping to show is that there are differences in inflammatory and immune responses between novices and experienced practitioners to show that yoga modulates the stress response.”

The study seeks to answer three specific questions:

· Are there reliable differences in behavioral, autonomic, endocrine, immune and cutaneous responses to a yoga session compared to the two control conditions;

· Do prior yoga experience and age relate to baseline differences, as well as behavioral and physiological responsiveness to the three intervention sessions; and

· How do an individual’s expectancies and mood influence behavioral and physiological responses to the interventions?

This same team of researchers’ previous work on the relationship between stress and health has concentrated on cytokines, compounds that start the healing process, and how stress hormones can slow the delivery of cytokines to injury sites, delaying the healing process. One cytokine in particular, however, called interleukin-6 (IL-6), has been linked to long-term inflammation when it is sustained at higher than normal levels, said Glaser, a professor of molecular virology, immunology and medical genetics. Those sustained higher levels of IL-6 have been linked to long-term inflammation, which can contribute to the development of such age-related illnesses as cardiovascular disease, osteoporosis, arthritis, type-2 diabetes and certain cancers, he said.

Malarkey, also director of the Clinical Research Center in which the study is conducted, noted that early acknowledgment of the mind-body connection is key to reducing the complications of aging.

“The notion here is we recognize that most disorders have a stress component that shows up very early,” he said. “If we can make small adjustments earlier in life, rather than waiting until we have a disease diagnosis, that will provide benefits for our own longevity.

“You can’t change your gene pool, but you can change your behavior,” he said.

This research is supported by the National Center for Complementary and Alternative Medicine, part of the National Institutes of Health.

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