If you are (or you’ve ever been) an avid runner or obsessive gym rat, you’re likely familiar with that coveted post-workout sense of euphoria popularized as the “runner’s high.” But what exactly is it? The runner’s high has been characterized in scientific literature as “pure happiness, elation, a feeling of unity with one’s self or nature, endless peacefulness, inner harmony, boundless energy, and a reduction in pain sensation.”
Some scientists hypothesize the runner’s high is a neurobiological reward following moderate to intense aerobic activity that incentivizes us to participate in habitual physical activity. It’s logical to think we developed this reward mechanism through evolution to get us off the couch (or out of the cave) and engage in health-promoting activities.
Interestingly, our ability to sustain highly intense endurance tests is unique in the animal kingdom. In a lecture, “Why Humans Run: The Biology and Evolution of Marathon Running,” Harvard Anthropology Professor Daniel Lieberman explains, “Hairless, clawless, and largely weaponless ancient humans used the unlikely combination of sweatiness and relentlessness to gain the upper hand over their faster, stronger, generally more dangerous animal prey.”
Not only can the effects from the “runner’s high” motivate us to exercise, they can help us sustain intensive aerobic activity over longer durations. Likewise, given the fact that intensive aerobic activity expends significantly more energy (and carries a higher risk for injury) than less intensive activities, this built-in neurobiological reward plays a vital role in motivating us.