MADELEINE BRAND, host:
What's the value of a good run? Well you could ask this guy.
Mr. ERIC FOSTER (Runner): Hi, I'm Eric Foster, and I'm training for Ironman currently at the moment. So today's the long run, so I'll probably do 15 miles and some hills.
ALEX CHADWICK, host:
OK, Eric Foster, he's kind of an extreme example, but we did talk to many people on their morning runs yesterday. People who run a lot.
Ms. LISA DAY (Runner): My name is Lisa Day (ph), and I run between 12 and 17 miles a week.
Ms. EILEEN KIM (Runner): Hi, I'm Eileen Kim (ph), and I run 30 miles a week.
Mr. KEVIN TIDELL (Runner): I'm Kevin Tidell (ph), and I run three to four times a week.
CHADWICK: And what value could these people be getting out of it? Why do they run so much?
Ms. DAY: I don't know, you just feel generally better about everything.
Ms. KIM: You feel like a burst of energy.
Mr. TIDELL: You know, not really light headed but you just feel like kind of on top of the world type feeling, like a rush.
Mr. FOSTER: It's kind of like a euphoric feeling, say a good high for a little while, and then you've just got to run again to get it.
BRAND: Ah ha, the ever famous runner's high. For years, athletes have claimed it really does exist. For those less athletically inclined, those claims make runners sounds like they are high on something else.
CHADWICK: But avid runner and New York Times science reporter Gina Kolata has now written about a new study that may finally put the skepticism to rest. This was conducted at the University of Bonn in Germany.
Ms. GINA KOLATA (Reporter, New York Times): They used the latest technology to actually answer this old question because I was never - it was always just sort of hanging out there as a popular hypothesis with no real evidence.
CHADWICK: The researchers scanned the brains of a group of runners before they ran for two hours.
BRAND: And afterward, they scanned their brains to see if endorphins were active in certain parts of the brain. Endorphins are those hormones that our bodies release to kill pain, kind of like a natural morphine.
Ms. KOLATA: Turned out that endorphins were attaching themselves to areas of the brain that really were associated with senses of well being, euphoria, calmness, all these things that people attribute to runner's high.
Mr. DAVID WILLEY (Editor, Runner's World): The problem is that some of the faults with that theory still haven't been fully debunked.
CHADWICK: David Willey knows about the runner's high. He is a runner. He is the editor in chief of Runner's World. There's a problem with the endorphin theory, he says. Because of our brain's physiology, endorphins really can't get into it. But one protein can.
Mr. WILLEY: It's a fatty acid called anandamine, which is the Sanskrit word for bliss, and it's similar to THC, which you can find in marijuana.
BRAND: So maybe long distance running just got a lot more appealing, but Gina Kolata of the New York Times doesn't think this proof of runners high is going to result in masses of non-runners hitting the pavement.
Ms. KOLATA: If you don't like running, I can tell you a thousand times, oh you'll get a runners high. You're just going to look at me like I'm crazy.
CHADWICK: Day to Day is a production of NPR News with contributions from Slate.com. I'm Alex Chadwick.
BRAND: And I'm Madeleine Brand.