They've been chasing runner's high for the last 25 years, and, until very recently, have come up empty handed. In her personal and scientific journey, Ultimate Fitness: The Quest for Truth about Exercise and Health, New York Times science writer Gina Kolata devotes more than 20 pages to the quest for runner's high. In the end, she concludes it's a myth.
Kolata notes that running and runner's high seem linked more by chronological association than by scientific proof. Endorphins, some of the body's natural painkillers, were discovered in 1975. Running took off a few years later. Soon, legions of runners were bumping into each other at weddings and cocktail parties, saying things like: "Who needs drugs? I get an endorphin rush every time I run more than 10 miles."
Of course, talk is cheap. Science demands rigorous proof. And last year, in her book and a Times article, Kolata pretty much buried runner's high forever. She interviewed a number of leading experts, and none of them bought into the runner's high theory. "I believe this endorphin in runners is a total fantasy in the pop culture," said psychobiologist Huda Akil, Ph.D., from the University of Michigan.
The endorphin theory had several problems, the most serious being that endorphins are too large to pass through the blood-brain barrier that border-patrols your gray matter. And if something can't get into your brain, it can't make you high. Too bad. What are we going to talk about at cocktail parties? Turns out the answer could be that 1960s favorite: marijuana.
A year ago, Kolata couldn't have known about the work of a marathoning neuroscientist named Arne Dietrich, Ph.D., now at the University of Beirut. He considers himself more a memory specialist than a brain-chemicals guy, but Dietrich has run six marathons with a best of 2:52, and he had to think about something when he was out there.
From his readings in the field, Dietrich knew about a relatively new brain receptor site, first discovered in 1990. This site was shown to be the receptor for THC, the active ingredient in marijuana that produces another kind of high entirely. The site was named the cannabinoid receptor.
Since the body is an intelligent system that doesn't develop receptors for no reason at all, this meant the new receptor must be home to a natural body chemical--and not just THC, an exogenous, or "outside the body" substance. The natural chemical was discovered in 1992. It's called anandamide, from the Sanskrit word for "bliss." Anandamide is very similar to THC, and it produces pleasant feelings of relaxation and pain cessation similar to those often described by runners and pot smokers.
Could anandamide be the missing link to runner's high, the substance that endorphins were not? On one long run, Dietrich worked out all the details. "I was convinced that I had hit the nail on the head when it came to a biological explanation for runner's high," he says. "Of course, it would take me two years to prove it."
He started by devising a simple experiment with a small group of subjects who ran or bicycled for 40 minutes at 76 percent of their max heart rate, and then had blood samples drawn immediately after exercising. Next the blood samples were flown to a special lab in Irvine, California. The results showed that both the runners and bicyclists had significantly more anandamide in their blood after exercising, with the greatest increase among the runners.
