If we run another 23 miles, we might catch a serious buzz! Or we could spark up a doobie...
It has long been thought that “runner’s high”, that euphoric feeling that sometimes accompanies intense cardiovascular exercise, was a product of one’s endorphins, those opiate-like molecules our body produces to mitigate pain. But these molecules are far too large to pass the blood-brain barrier, so even though endorphin levels rise during exercise and mitigate the stress we feel physically, there is no biological reason there should be an accompanying mental “high”.
Recent research, however, has uncovered the role of our natural endocannabinoid system in producing the “runner’s high”. We have endocannabinoid receptors throughout our brains and bodies and this is the system that is activated by consuming cannabinoids in plants, namely, cannabis. It turns out this system could be the reason for the “runner’s high” as exercise produces extra endocannabinoids.
(New York Times) In a groundbreaking 2003 experiment, scientists at the Georgia Institute of Technology found that 50 minutes of hard running on a treadmill or riding a stationary bicycle significantly increased blood levels of endocannabinoid molecules in a group of college students.
Since that 2003 study, a flurry of research has been teasing out the role that endocannabinoids play in the body’s reaction to exercise. In some of Dr. Hill’s work, for instance, rats treated with a drug that blocked their endocannabinoid receptors did not experience the increase in new brain cells that usually accompanies running, suggesting that a well-functioning endocannabinoid system may be required for cognitive improvements from exercise.
But perhaps the most telling experiment was published last year by researchers in France who had bred mice with no functioning endocannabinoid receptors. Mice usually love to run, but the genetically modified animals, given free access to running wheels, ran about half as much as usual. Although the full intricacies of the endocannabinoid system’s role in motivating and rewarding exercise is not yet understood, it seems obvious, the researchers say, that the cannabinoid-deprived mice were not getting some necessary internal message. Typically, the endocannabinoid system “is well known to impact onto central reward networks,” the authors write. Without it, exercise seemed to provide less buzz, and the animals didn’t indulge as much.
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