The New Science Behind Runner’s High

Molly Hurford
by Molly Hurford
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The New Science Behind Runner’s High

Ever get that elusive feeling on a run where your legs suddenly feel weightless and you feel like you’re floating from step to step, smashing PRs along the way — and loving absolutely every person and every thing? Welcome to the runner’s high, the reason why running is so addictive.

The good news: It’s not just in your head. The bad news: Science doesn’t really know how to explain it, either.

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In 1990, one scientist came close. Mihaly Csikszentmihalyi published his landmark book on the concept of the flow state, which is similar to runner’s high. Flow state can happen anytime, but it’s most commonly referenced in sports. Being in the flow state means feeling “strong, alert, in effortless control, unselfconscious, and at the peak of their abilities,” he wrote. Sounds a lot like how you would describe runner’s high, right? And to get to that flow state, you need to be fully immersed in an activity — usually one that’s doesn’t come easily, like a hard run — before you get there.

“Most enjoyable activities are not natural; they demand an effort that initially one is reluctant to make,” he explains. “But once the interaction starts to provide feedback to the person’s skills, it usually begins to be intrinsically rewarding.” In short, finding your flow is sinking into a mental state that has the physical side effect of a euphoric feeling.

Despite all that, the exact reason why we get into a state of runner’s high was still elusive. In the “Encyclopedia of Sport and Exercise Psychology,” Michael Sachs suggests that it’s a combination of factors ranging from the psychological — entering Csikszentmihalyi’s flow state — to the more biological: the release of endorphins and other hormones flooding the brain. However, he notes that it’s a hard concept to study, since the runner’s high is often accomplished when runs are unmonitored and untethered, and it’s nearly impossible to test for it on a treadmill in a lab.

So why do we get a feeling of euphoria doing something that may not be super fun? It might be an evolutionary mechanism designed to convince us to keep running to stay healthy. A 2012 study in the Journal of Experimental Biology explains it this way: “Humans report a wide range of neurobiological rewards following moderate and intense aerobic activity, popularly referred to as the ʻrunnerʼs high,ʼ which may function to encourage habitual aerobic exercise.”

The study looked at endocannabinoids, a group of endogenous neurotransmitters that they believed play a major role in generating this feeling — a reward — by activating cannabinoid receptors (the very same system of the brain associated with a marijuana buzz). Testing done on both humans and dogs for the study showed that high-intensity endurance running indeed led to increased endocannabinoid signaling. Low-intensity walking, on the other hand, did not.

A 2008 study also backs up the biochemical theory: Monitoring runners’ brains after long-distance runs showed a perceived increased level of euphoria similar to the effects of taking an opiate like morphine. A 2015 study done on mice concluded the same thing, saying that the mice experiencing runner’s high were the ones with the best endocannabinoid reception in their brains. “Running exercise increases blood levels of both beta-endorphin (an opioid) and anandamide (an endocannabinoid),” the study notes. Assuming your hormones are regulating properly, that’s a physical feeling of euphoria, not just an emotional one based on being almost done with a run — so it’s not just in your head!

How exactly you can get a runner’s high and why you have it are still mysteries, and maybe that’s not a bad thing. Sachs writes, “The runner’s high is likely to remain, for the moment, an elusive but highly desirable and wondrous experience.”

Want to find it for yourself? There’s no faking a runner’s high. You just have to go out, run hard and hope your brain chemistry kicks in.


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About the Author

Molly Hurford
Molly Hurford

Molly is an outdoor adventurer and professional nomad obsessed with all things running, nutrition, cycling and movement-related. When not outside, she’s writing and podcasting about being outside, training and health. You can follow along with her adventures on Instagram at @mollyjhurford.


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