For decades we’ve believed that endorphins (naturally-occurring painkillers in our bodies) were the chemicals responsible for what’s commonly known as a “runner’s high.” In case you aren’t familiar with the term, a runner’s high can be experienced by pushing yourself hard with any serious exercise. Without getting too technical, when somebody hits a certain point of exertion, their brain will reward their efforts with a lovely burst of chemicals. This cocktail causes a pretty intense sensation of euphoria, happiness, excitement and a floaty feeling. The fact we thought this high was caused by endorphins makes sense, as full-on exercise will lead to physical discomfort, and physical discomfort causes your body to dispense endorphins as a natural painkiller. As endorphins have a lot in common with morphine, this explains the pleasurable effects. Logical, right?
Or at least that’s what we thought.
The latest findings suggest that runner’s high is actually caused by the body’s own naturally-occurring endocannabinoids, which are chemicals that have a lot in common with marijuana. In addition to causing pot-like effects on the human brain, endocannabinoid molecules also have a similar size to cannabis molecules. This is a very important fact, as the size issue is the exact reason why we know endorphins don’t deserve the credit anymore.
The fact is that endorphin molecules are much, much larger than endocannabinoid molecules, and are simply too big to pass through the blood-to-brain barrier. So while endorphins have the ability to soothe pain in your muscles, for them to cause a euphoric effect they’d have to hop from the bloodstream and into your brain, which isn’t possible. It’s a camel-and-the-eye-of-the-needle situation, and endorphins are the camel.
A team at the University of Mannheim in Germany started looking for another suspect, and endocannabinoids were the most likely culprit. For one, the cannabis molecules in pot are definitely small enough to cross the blood-brain barrier and attach to your receptors (as half of society can personally appreciate). The German scientists tested their theory by blocking off the endocannabinoid systems of some mice. As soon as this chemical was taken out of the equation, those particular squeakers ceased to get the benefits they’d usually receive from their time on the wheel, and became noticeably more anxious and twitchy (which is the definition of a mouse, so that’s saying something). Blocking the endorphin systems of a second group of mice, however, had no effect on the benefits they got from running, and they carried on as normal.
“Oh man, that wheel was SOOO good! I wish I was running on it right now!”