No one doubts that exercising is good for your health. But exercising to extremes can become a physical addiction . This conclusion has been reached by Robin Kanarek of Tufts University and his colleagues. In experiments with 84 rats they found that, after spending too much time running on their wheels every day, the rodents showed a certain degree of addiction. To measure it, they were administered naloxone , a drug that does not produce any effect in healthy individuals but that, in individuals with dependence, generates withdrawal syndrome. Rats that had been subjected to excessive physical activity developed withdrawal symptoms : pupillary dilation, tachycardia, muscle tremors, … This response indicated that the same changes experienced by drug users had occurred in their brain .
"Exercise, like drug abuse, causes neurotransmitters such as endorphins or dopamine to be released excessively, linked to the sensation of reward," concludes the researcher.
From the results, the scientists suggest that, if exercise can become so addictive, a possible therapy for drug addicts would be to substitute drugs for sports.
