Athletes describe runner's high as euphoria, a loss of pain, heightened awareness.
The cause: our bodies produce narcotic-like chemicals during continuous aerobic exercise, said George J. Trachte, Ph.D., interim department chair of Biomedical Sciences at the University of Minnesota Medical School, Duluth Campus.
What happens during strenuous exercise is the brain secretes endorphins — "similar to morphine, but we make it ourselves," he said — and a marijuana-like chemical, anandamide, a type of endocannabinoid.
It doesn't happen immediately, but if you feel discomfort or pain, this makes it easier to continue, and it could contribute to runner's high feelings, he said.