Jogger in Washington D.C. (Photo : Reuters)
A popular, long-held theory is that the feeling of ecstasy and relaxation that a runner has after an intense exercise session (runner's high) results from "happy" chemicals known as endogenous morphine or endorphins. However, a new study with lab mice implies that the runners' feel-good phenomenon could be the result of chemical compounds called endocannabinoids, which create the "high" caused by marijuana's -tetrahydrocannabinol (THC).
The study was conducted by researchers at the University of Heidelberg medical school in Mannheim, Germany.
In the research scientists found higher levels of endocannabinoids (natural type) in people's and animals' blood. This was after exercising.
The researchers compared endorphins' and endocannabinoids' effects. They put lab mice on wheels and then conducted some tests.
After running, the mice were calmer and less pain-sensitive. They also had high levels of endorphins and endocannabinoids.
Next, the researchers then used drugs to block the effects of one of the chemicals. When they blocked the effects of endocannabinoids, the runner's high symptoms vanished, according to Business Insider. However, when they blocked the endorphins in the mice no changes happened. .
The findings suggest that the post-run buzz was the result of endocannabinoids rather than the endorphins. However, it is unclear if the same effect would occur in humans.
Endorphins function as the human body's natural painkillers. After scientists learned in the 1980s that endorphin blood levels spiked after exercise, the assumption was that this created the feelings of elation in the brain.
There is a big problem. Researcher Johannes Fuss explained that endorphins are too large to fit through the "gate" between the blood and brain, so it is impossible they cause the high after a good run, according to Scientific American.
For the past decade researchers have been searching for another explanation. They discovered that cannabinoids are small enough to cross the blood-brain block and attach brain receptors.
