For years, scientists maintained that exercise-induced endorphin highs were the stuff of myth. We're happy to report that they were dead wrong.

As marathoner Deena Kastor crossed the finish line at the 2004 Olympics in Athens, winning a bronze medal, she felt as if she could have run another few miles at the same pace. When Ryan Hall

SLATER ON NATURAL HIGH "There are all these chemicals your body releases. And when they're released in the right way, they can be stronger than any drug, with no bad side effects. Some days it happens, some days it doesn't. That's part of the beauty of it."

shattered the U.S. half-marathon record in 2007, he had an almost out-of-body experience, watching himself from above as he crossed the finish line. Even I, a half-assed jogger, occasionally experience a soothing calm during my lung-searing runs through the diesel-particulate fog near the Brooklyn-Queens Expressway.

All these sensations are different forms of runner's high, a phenomenon that endurance athletes have celebrated for decades but that, until recently, was as scientifically proven as Sasquatch. That's because there wasn't a way to observe the effect of endorphins—the body's self-produced opium—on the parts of the brain associated with exhilaration and euphoria. While plenty of studies found endorphins in the bloodstreams of people who'd just finished exercising, scientists debated whether or not those endorphins actually pass through the blood-brain barrier. Some thought the high was a myth.

But then a study published last year by researchers at the Technical University of Munich, Germany, gave ample evidence that runner's high is very much real. Neurologist Henning Boecker gathered ten runners, injected them with radioactive (but safe) tracers, then took a PET scan—a noninvasive snapshot—of their brains. On another day, Boecker's team took scans immediately after the runners com­pleted a vigorous two-hour workout. Result: The tracers showed endorphins busily binding to receptors in the limbic and prefrontal portions of the brain—the areas responsible for feelings of ecstasy and joy. "We'd suspected that the release of endorphins must come from the brain," says Boecker. "But nobody was ever able to show that until now." (Prior to Boecker's PET scans, the only way to disprove the skeptics would have been to subject runners to a spinal tap—not an easy study to recruit for.)

To a lot of runners and coaches, this was a case of science catching up with common knowledge. "It would be more surprising if they found nothing," says Terrence Mahon, Hall's coach. "Any runner could tell you runner's high exists," adds obsessive ultramarathoner Dean Karnazes, who recently ran for 48 hours straight on a treadmill. "When I'm able to push through the pain and not black out, I arrive at a different place." [Editor's note: Not recommended.]

But Boecker's research goes beyond just vindicating those who swear by an athletic high. The fact that endorphins can give you a lift means that running—or cycling, or swimming, or any endurance sport—has the potential to treat depression, addiction, and pain, though more research is required. Once laughed at, runner's high could, before too long, become a staple in your doctor's Rx closet.

TAKE ACTION:
Tie One On
It feels sooo good. Trust us.

1. Build a base first. If you're a newbie, jog for 30 minutes three times a week. If your muscles and bones are sound, your runs should start to feel good in three to four weeks.

2. Everyone's endorphins kick in at different points—it's all about intensity in regard to your personal limits. Figure out a tough one-mile pace for yourself, and try to run at 80 to 85 percent of that speed for the longest distance you're comfortable, whether it's two miles or ten. Just don't try to sprint to a runner's high—intervals place such a huge demand on the body that you'll never have a chance to enjoy the endorphins.

3. Train in the best outdoor setting you can find. "I don't know whether it connects with serotonin levels, or endorphins, or dopamine," says Mahon, who coaches distance runners among the peaks of Mammoth Lakes, California. "But from an anecdotal standpoint, people are drawn to the outdoors because it makes their bodies feel good."