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Posted on 12/01/2003 8:10:32 AM PST by milestogo

Exercise is as addictive as booze and fags, say scientists

Tim Radford
Monday December 1, 2003
The Guardian

It's now official. Some joggers may become addicted to running just as other people become hooked on cocaine, tobacco or booze, according to new research today.

The proposition that exercise can trigger a "high" based on brain chemistry has been around for decades. But there has been less research into what happens when the trainers are locked away and the tracksuit sent to the cleaners. Now a team from the University of Wisconsin-Madison has confirmed that not pumping iron or pounding the pavement could trigger telltale changes in neuronal activity. They watched mice manically sprinting on exercise wheels and then measured withdrawal symptoms when they are kept off the treadmill.

"In the high running mice, certain brain regions displayed extremely high levels of activity, more than normal," said one of the researchers, Justin Rhodes. "These were the same brain regions that become activated when you prevent rats getting their daily fix of cocaine, morphine, alcohol or nicotine."

He and colleagues at Wisconsin report in the December issue of Behavioral Neuroscience that they worked with two populations of laboratory mice.

Some were normal or "couch potato" mice and others were marathon mice, a special breed selected over 29 generations for their enthusiasm for exercise.

Scientists were surprised to find that mice prevented from running showed surges of neuronal response. The more compulsive the urge to run, the higher the surges when the treadmill was locked away. These surges were the equivalent of cocaine cravings in human drug addicts.

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