Not that any of us needed any proof, but researchers now have scientific evidence that the "runner's high" -- that euphoric, calm state that we feel at the end of a long run -- does exist. More specifically, scientists in Germany found that the body's endorphins are responsible for the runner's high. Using brain imaging, they were able to show the increased release of endorphins in certain areas of athletes' brains during a two-hour running session.

Now if only those scientists could figure out a way to make the runner's high last longer...

Why People Run

Exercise and Stress Relief

_{The Runner's High: Opioidergic Mechanisms in the Human Brain,Cerebral Cortex , February 21, 2008}