Research at Tech locates source of ‘runner’s high’ experienced by athletes

Sean Selman
Institute Communications and Public Affairs

A new study conducted at Georgia Tech and the University of California, Irvine suggests that a class of chemicals known as cannabinoids may be the missing piece of the “runner’s high” puzzle long-sought by scientists.

“Exercise is good for the mind. For the millions of people who exercise, this is not a secret,” said Arne Dietrich, the study’s principal investigator and a former visiting professor. “It helps reduce stress, lowers anxiety, suppresses pain, produces a feeling of well-being and can even lead to a euphoric state. To scientists, however, the process that leads to this last phenomenon — popularly known as the ‘runner’s high’ — remains an elusive mystery.”

	During moderate exercise, a naturally occurring chemical produces effects similar to that of the psychoactive ingredient in marijuana.

A critical clue in the mystery may have been found, however. As published recently in the journal Neuroreport, Dietrich’s research team has found high levels of a naturally occurring cannabinoid called anandamide in runners and cyclists who exercised at moderate intensity for an extended period.

Anandamide produces effects similar to those of THC, the psychoactive constituent of marijuana, leading researchers to speculate that “runner’s high” may not be caused by endorphins released by the human body – as previously thought — but by a naturally occurring cannabinoid high.

This study was conducted this past year in Georgia Tech’s Exercise Physiology Laboratory – part of the School of Applied Physiology — when Dietrich was a visiting professor from the Georgia College and State University’s Department of Psychology.

“I was aware of the limitations of the endorphin theory for explaining the runner’s high, and I thought that Dr. Dietrich’s novel hypothesis fit well within recent endocannabinoid discoveries,” said Professor Phil Sparling, co-director of the Exercise Physiology Lab and Dietrich’s host at the Institute.

Of interest to researchers when they began their investigation were cannabinoids produced naturally in the human body, called endocannabinoids.

”The body’s endocannabinoid system has evolved primarily for pain modulation — that is, pain or stress activates the system naturally,” Dietrich said. “This activation, in turn, helps the body to modulate pain.”

This natural analgesic system is independent of and complementary to the body’s opioid system, he said, and it performs other natural functions such as vasodilation, bronchodialation and sedation.

Dietrich believes the human body begins to produce high levels of cannabinoids — and thus a natural “runner’s high” — during moderate-to-intense exercise that produces prolonged stress and pain.

It does not appear that this effect causes any harm to runners and athletes, however.

“In exercise, there is a reason why the endocannabinoid system is activated,” Dietrich said. “One has to deal with a physical stressor, and the endocannabinoid system fulfills its purpose. Smoking marijuana is a different story. This is an unnatural abuse of the system, not intended to be used this way by evolution.”

Dietrich believes this study provides a viable biological mechanism to explain the “runner’s high,” and it suggests that exercise might be useful in the treatment of chronic pain or glaucoma, both of which are treated in some parts of the country in clinical experimental trials using plant-derived cannabinoids such as THC.

Faculty development

Dietrich is an assistant professor of psychology at Georgia College and State University in Milledgeville, where he also directs the Department of Psychology’s Behavioral Neuroscience Laboratory. His one-year stay at the Institute was made possible through the College of Sciences’ Faculty Development Program, which Dean Gary Schuster said provides an exciting way for the Institute to help advance science throughout the state.

“The whole idea here is that Georgia Tech has resources available to it that some other institutions in the University System of Georgia do not, and faculty members at those institutions need to stay current in their disciplines just as much as ours do,” Schuster said. “After all, only people who are active in their disciplines can transmit that excitement and inspiration on to their students.”

The Faculty Development Program provides an opportunity for other University System of Georgia faculty to spend either a semester or a year at Georgia Tech, collaborating on research and teaching students.