Endocannabinoids and runner’s high
I’ve written about endocannabinoids in earlier posts, but new studies involving endocannabinoids and exercise recently caught my attention. And boy, was I surprised. I’m sure most of us have exclaimed at the end of a good run, “My endorphins are kicking in!” Endorphins are our body’s naturally produced opioids. Endorphin” comes from combining “endo” (within) and “morphine,” which refers to that opiate. Endorphins have long been credited with producing “runner’s high,” that wonderful sense of well-being and euphoria that swells over us after a great workout. Scientists have called runner’s high “pure happiness, elation, a feeling of unity with one’s self or nature, endless peacefulness, inner harmony, boundless energy, and a reduction in pain sensation.” And I, for one, have praised and thanked endorphins over the years for that great feeling. It turns out that I might have been wrong.
New findings suggest that endorphins aren’t responsible for runner’s high. Instead, scientists increasingly believe that this euphoric feeling may be produced by a completely different but somewhat familiar substance — our body’s own endocannabinoids. These are chemicals that – similar to the cannabinoids in marijuana – “put you in a better mood.” Even sea sponges have endocannabinoids, predating the five-leaf plant that most are familiar with by some 30,000. We’re talking about an old system in our bodies! Back in the 1980s, researchers found that blood levels increased after extended exercise. And, since exercise can cause discomfort or pain, the body produces endorphins that have pain-relieving properties similar to morphine. It made sense then that endorphins were probably what caused the sensations of well-being and euphoria that many people feel when they’ve exercised. There was just one problem with this theory.
Endorphins might relieve muscular pain, but they can’t have any direct effects inside the brain because they are too large to pass through the blood-brain barrier. And it’s inside the brain where we get “high” so to speak. Consequently, scientists began to look for other substances that might make exercisers feel high. Guess what they found – endocannabinoids, especially anandamide (one of the unsung heroes of the “feel-good” chemicals). Research on mice and other animals prompted researchers to explore cannabinoids and the endocannabinoid system. Endocannabinoids are, essentially, internally produced marijuana, or cannabis. Cannabis contains cannabinoid molecules, and they are small enough to cross the blood-brain barrier and attach there to receptors, producing that “dude, I’m high – got anything to eat?” feeling.
Researchers now know that exercise raises the levels of endocannabinoids in the bloodstreams of people and animals, and that makes these molecules good candidates to underlie the runner’s high. Until recently, few studies have directly compared the effects of endorphins and endocannabinoids to determine which really makes exercise mildly intoxicating. A recently published study in Proceedings of the National Academy of Sciences featured experiments carried out at the University of Heidelberg medical school in Mannheim, Germany. Researchers there put healthy lab mice in running wheels and let them run, which they like to do even if nothing is chasing them. This suggests that they may be getting some sort of mental satisfaction from it – maybe a mouse’s runner’s high. Researchers found that endorphin and endocannabinoid levels in the animals’ bloodstream were elevated after running and that the mice were calmer and more pain tolerant. You can read more about this at https://www.pnas.org/content/early/2015/09/29/1514996112 .
In a similar study (https://www.ncbi.nlm.nih.gov/pubmed/22442371) that compared humans, dogs and ferrets, researchers hypothesized that “intense aerobic activity could trigger neurotransmitter signaling associated with the endocannabinoid system. The group focused on anandamide, a cannabinoid known as the bliss molecule.” Anandamide gets its name from the Sanskrit word, “Ananda,” and is a twin to THC, (Tetrahydrocannabinol), the compound in cannabis that is psychoactive and gives you the feeling of being high. Anandamide, like THC, activates certain receptors to produce psychological and physical rewards like euphoria and pain relief (but doesn’t pack the same punch that Mother Nature has put in cannabis). Researchers found that humans had significantly higher anandamide levels after an intense run. The study would seem to indicate that if you want to pump up your anandamide levels, intensive aerobic activities will give you the best bang for your buck rather than walking. Whatever the case, the “runner’s high” is a great natural buzz that serves as a powerful motivator to continue training. Now I can stop saying, “my endorphins just kicked in,” and instead start saying “my endocannabinoids (anandamide) are kicking in!”
It’s amazing what we’re learning about the power of our bodies, minds, micro-dosing, altered states and a wide range of other subjects that we’ve ignored for so long. And none of this should surprise us. There is so much about the power of our bodies that scientists are only now discovering. After all, as an unknown sage has said: we’re nothing more that eternity and starlight dressed up as billion-year-old carbon! Who says you can’t teach an old dog new tricks!