Athletes sometimes say they experience a runner’s high or are “addicted” to exercise.

In fact, scientists have shown that rhythmic, continuous exercise — aerobic exercise — can in fact produce narcoticlike chemicals in the body.

Now researchers suggest that those chemicals may have helped turn humans, as well as other animals, into long-distance runners causing them to experience runner’s high.

The man behind the research is University of Arizona anthropologist David Raichlen, a runner himself. He does about 25 miles a week.

Being human, Raichlin has some tools that help — short toes that don’t get in the way, for example, and big joints in the legs to absorb shock. But he thinks humans are also “wired to run.” 

“Wired to run, meaning that our brains are probably, have been sort of rewired from an evolutionary sense to encourage these running and high aerobic-activity behaviors,” Raichlen says.

Many anthropologists think early humans learned to run long distances to chase down and exhaust prey, like antelopes.

Meat is one payoff for runners. But Raichlen thinks there may have been another reward: a runner’s high. He designed an experiment to test this idea.

But first, let’s take a look at this thing they call a runner’s high.

I caught up with Christina Morganti to learn more. She’s an orthopedic surgeon at the Anne Arundel Medical Center in Maryland, and a longtime competitive runner.

She runs races, but not for medals. “To be honest,” she says as she starts a morning run on a sunny spring day, “I don’t really care that much about the competition as much as that feeling you get when you’re in shape. That’s what I’m looking for.”

She starts slowly. “You know, when you first start, you feel a little stiff, a little logey, but then once you get started, everything loosens up.”

As a doctor, Morganti knows what regular running does for her body. “Your heart gets stronger. It gets bigger. The amount of blood your heart can pump is more.” That’s called “stroke volume.” Oxygen metabolism gets more efficient, as well. “That means your blood vessels and muscles absorb more oxygen,” she says. “Running also builds new bone.”

But when I ask her about “a runner’s high,” she lights up. “Oh, it’s really like an empowerment. And zen at the same time. You feel strong and light, and you feel relaxed.”

Morganti injured herself running two years ago and had to stop running. “And everything else fell apart,” she admits. “My ability to cope with the stresses of life, my organizational skills juggling your job and motherhood, everything like that, wasn’t as acute as it was when I was able to run and be fit.”

About 3 miles into the run, Morganti is getting her rhythm but also feels some pain… CONTINUE READING


runner's high

Christopher Joyce is a correspondent on the science desk at NPR. His stories can be heard on all of NPR’s news programs, including NPR’s Morning EditionAll Things Considered, and Weekend Edition.