Runners and potheads may experience similar highs because the chemicals that cause each of them are very similar, scientists have found in a new study.
According to The New York Times, runners commonly cite a rush of endorphins for the euphoric feeling that frequently accompanies a workout. The feeling likely has much more to do, however, with the body's own endocannabinoids, which are similar to the cannabinoids in marijuana.
Scientists studying mice published new findings this week in the
Proceedings of the National Academy of Sciences that suggest that endorphins are unlikely to cause runner's high because endorphin molecules are too large to pass through the blood-brain barrier.
"They might staunch pain in the muscles, but they wouldn’t have effects directly inside the brain, where any high would originate," explained the Times.
With that suspect eliminated, scientists are now pointing to endocannabinoids as the likely source of the natural high.
During the experiment, scientists had one group of mice run on a treadmill, and forced another group to be inactive for five hours. The mice that did not work out were much more likely to exhibit anxious, non-euphoric behavior, such as staying in the shadows and avoiding pain at all costs.
In a follow-up round, the researchers added endocannabinoid and endorphin antagonists.
"We thus show for the first time to our knowledge that cannabinoid receptors are crucial for main aspects of a runner’s high," the researchers wrote.
The Washington Post reported another research team has suggested in their own study that the hormone leptin, which regulates energy stores in the body, could also play a part in producing a runner's high.
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