Runner’s High May Come From More Than Endorphins

The famous “runner’s high” is probably not mainly caused by endorphins, as people believed for years. During long-lasting exercise, the body increases its production of endocannabinoids—natural substances that act on the same receptor system affected by cannabinoids found in marijuana.

In marathon runners, levels of anandamide, whose name comes from a Sanskrit word meaning “bliss,” began rising clearly during the run. This went along with less anxiety, less pain, and a better mood.

Interestingly, an even longer run does not necessarily mean a stronger feeling of euphoria. In one study, ultramarathon runners covering 100 to 230 kilometers had lower endocannabinoid levels than regular marathon participants, probably because their effort was less intense and their bodies were extremely exhausted. Of 36 ultramarathon runners, 12 reported a clear runner’s high. Another endocannabinoid, 2-AG, stayed elevated longer and may help control inflammation and support the body’s recovery after extreme exercise.