runner’s high?

Most of us know a compulsive runner or gym rat who completely freaks out if they have to miss a workout, but it’s been debated whether exercise addiction is a real or imaginary phenomenon. Now a study from the University of Wisconsin-Madison in the Dec. 1 issue of Behavioral Neuroscience suggests that it may indeed be a physical condition. Researchers showed that animals deprived of exercise revealed brain activity normally associated with drug withdrawal. Zoologist Stephen Gammie and his colleagues studied a special type of mouse, bred to run longer distances than the typical lab mouse. Both the “high-running” mice and the lab mice were allowed to run on a wheel for as long as they liked for six days, with the high-running mice running as much as three times farther in the same amount of time than the lab mice. On the seventh day, the researchers denied access to the wheel to half of the mice in each group, allowing the others to run as before. Then the researchers measured the brain activity in each group. All the mice denied the wheel showed high levels of activity in 16 out of 25 brain regions, but, stated Justin Rhodes, one of the paper’s authors, “in the high-running mice, certain brain regions displayed extremely high levels of activity, more than normal. These were the same brain regions that become activated when you prevent rats from getting their daily fix of cocaine, morphine, alcohol, or nicotine.” Whether these findings apply to humans still remains to be seen, but true “gym mice” appear to exist after all.

This news brief appeared in the Random Data column of the Boston Globe’s Health/Science section on 12/09/2003.