We all are familiar with the much sought after runner’s high. For many years we have explained this high in terms of the release of endorphins, our natural opiates, to explain the phenomena while running. I have actually had this happen on runs a few times over the years where it felt like I was getting IV Demerol. It seems, however, that another mechanism may be more commonly at work.
Several years ago, the natural neurochemicals related to marijuana were identified. They are the endocannabinoids. A paper entitled “Wired to run: exercise-induced endocannabinoid signaling in humans and cursorial mammals with implications for the runner’s high”, published in 2012, showed that more intense aerobic exercise activated the release of endocannabinoids in cursorial mammals. Cursorial mammals are defined as those designed to perform endurance running. This study also showed that cursorial mammals, humans and dogs, experienced this release and non-cursorial mammals did not experience it at a significant level.
The authors postulate, “a neurobiological reward for endurance exercise may explain why humans and other cursorial mammals habitually engage in aerobic exercise despite the higher associated energy costs and injury risks, and why non-cursorial mammals avoid such locomotor behaviors.”
Perhaps this is why runners experience a “chilled out” feeling during and after a run. It’s a great treatment for stress and anxiety.