Wanna know what's going on in your brain during that surprising mid-marathon elation? Your body just got you stoned, dude.
According to a team of researchers from the University of Mannheim in Germany, the "runner's high" is probably not from a massive release of endorphins, the happy chemicals your brain makes, like we previously thought.
In a paper in the journal Proceedings of the National Academy of Sciences, researchers argued that the "I'm sweaty and everything feels great!" sensation comes from your body producing endocannabinoids — which are also the driving force behind the uplifting, blissed-out effects of marijuana.
The study found that, after lab mice spent time running on a wheel, their anxiety levels and pain sensation were reduced, and both their endorphin and endocannabinoid production had increased. Essentially, they got high from the inside.
Here's the big discovery: The team went further to show that if they blocked production of endorphins, the mice didn't change — they still had low pain sensitivity and stayed out in the open, which is only seen in the least anxious mice in a lab setting. But when researchers halted the reception of endocannabinoids, the effects of their long wheel runs — which, apparently, averaged three miles a day — stopped short.
The problems: Unfortunately, the tests weren't run on humans, so we don't really know how that three-mile run in mice translates to our substantially larger bodies, and the Mannheim team isn't positive it works the same way. Also, according to the study, euphoria in mice "cannot be studied."
More than anything, it's another step toward learning about how our bodies and brains may actually work, updating a long-running myth about our anatomy.
h/t Business Insider