In February, however, the scientists at the University of Bonn in Germany settled the dispute. They examined 10 long-distance runners before and after a two-hour jog and were able to show conclusively a marked increase in the release of endorphins in the brain.

In addition to endorphins, researchers have identified other chemicals that are stimulated by intense exercise: dopamine, the substance that allows us to feel pleasure; serotonin, which acts as an antidepressant; and epinephrine, the body’s natural amphetamine. It seems likely, then, that the runner’s high is caused not by a single substance but by a whole cocktail of chemicals. This helps explain why celebrities such as Robert Downey Jr., Anthony Kiedis, and Owen Wilson have conquered their demons by becoming workout junkies.

Todd Crandell, who founded Racing for Recovery seven years ago, shares a similar life story with Charlie Engle. At the height of his addiction, he was drinking two fifths of Jack Daniel’s and snorting three or four grams of cocaine a day, supplemented with heroin, crystal meth, Valium, LSD, marijuana, Quaaludes, basically anything he could get his hands on.

"When I woke up in the morning, my first thought would be, Damn, I’m still alive. How much of this stuff is it going to take for me to overdose and die?" says Crandell. "It was a nightmare."

After 13 years as an addict, Crandell stopped using in 1993 and started participating in Ironman triathlon events, which consist of a 2.4-mile swim, a 112-mile bicycle ride, and a 26.2-mile run. Since 1999, the 41-year-old has completed more than a dozen Ironman challenges and has written a book about his struggles, Racing for Recovery: From Addict to Ironman.

"When I’m running, I feel like I’m on amphetamine," he says. "People say to me that I’ve just swapped one addiction for another addiction. They’re both highs, but one is destructive and the other is extremely productive."

Just how productive is evident from the testimonials of the many addicts Crandell’s organization has helped. A year ago, 33-year-old Eddie Freas’ crack cocaine habit was so bad he was suicidal. Then he saw Crandell being interviewed on ESPN and contacted him. Crandell moved Freas from his hometown in New Jersey to a facility called the Lifestyle Center in Toledo, where Freas began running as much as 50 miles a week. While he admits he still gets cravings, Freas says he hasn’t touched cocaine in six months. Recovering alcoholic Aaron Dalley, 28, lives and works at the same facility. "I wouldn’t say that if you go running you automatically get sober," he says. "But the exercise changes you. You sleep better. You eat better. It boosts your self-esteem, which makes it easier to concentrate on staying sober."

Researchers from Butler Hospital in Providence seem to back up Crandell’s program. They found that alcoholics who took part in 12 weeks of aerobic exercise were two and a half times more likely to remain clean and sober than those who didn’t exercise.

"There’s no doubt the drug high is more intense than the runner’s high," says Charlie Engle. "The main difference for me is that, with the runner’s high, I can enjoy the experience and not have to worry about the police coming to bust me. And afterward I can still go and pick my kids up for dinner."