Frequent runners know that not every run they set out on is going to be a good one. It just isn’t how running goes. Somedays are just, off.
But sometimes, when everything falls into place, an exceptionally good run happens and runners feel like they could go forever. And perhaps the best part about these runs is the elusive runner’s high that follows.
Not everyone has experienced a runner’s high. But those who have seek it almost like a drug, never wanting to come down from their cloudy, elevated state, and seeking it all the more intently the next time they hit the pavement. But where does a runner’s high come from?
Scientists believe the runner’s high is triggered by the endocannabinoid system. Similar to cannabis in marijuana, endocannabinoids are a chemical that can alter and lighten our moods. Our body produces them naturally, and have been shown to increase after prolonged running and cycling.
But what isn’t certain is how this sensation system has evolved and affected humans over the centuries, and whether the caveman human and 21st century human ran for the same reasons – driven by the runner’s high or not.
David A. Raichlen, a professor of anthropology at the University of Arizona, led a study on the runner’s high that was recently published in the Journal of Experimental Biology. He and his team looked at whether natural selection may have used neurobiological mechanisms to encourage exercise activity. They wondered if endocannabinoids played a role in the evolution of man, and wanted to know whether humans continued to run not because they had to for survival, but because they’d become hard-wired to actually enjoy it.
To test their theories, they compared the endocannabinoid response in species that historically are and are not runners, in order to see which animals experience a runner’s high. And the animal they chose to examine? The ferret.
Comparatively speaking, the human and the ferret are nothing alike. But scientists thought the animal a perfect subject since they are typically not likely to run long distances, and are somewhat slow-moving, unlike (active) humans. Scientists also used dogs in the study as they have an active nature similar to humans.
The scientists studied small groups of ferrets, recreational runners and dogs of varying breeds, taking blood samples before and after a 30 minute treadmill run at a challenging pace. Human endocannabinoid levels showed significant increases after running, as did the dogs – suggesting for the first time that they too experience a runner’s high. While the ferrets showed no increase after exercise, suggesting they gain no real pleasure from running.
What Dr. Raichlen and his team believe these findings suggest is that a ‘reward response to aerobic activity seems to be part of our evolutionary history. And furthermore, that it appears humans have the evolutionary drive to exercise, but over time we’ve learned to ignore it – which is why so few humans run today.’
While the study was somewhat isolated and the findings can’t be taken as absolute truth, scientists were pleased with the results and believe it provided some evidence that our evolutionary history may include a reward system for endurance activities, and that we are in fact, naturally hard-wired to move.