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It hurts so good: the runner’s high

The views expressed are those of the author and are not necessarily those of Scientific American.

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I just came back from an 11 mile run. The wind wasn’t awful like it usually is, the sun was out, and I was at peace with the world, and right now, I still am. Later, I know my knees will be yelling at me and my body will want nothing more than to lie down. But right now? Right now I feel FANTASTIC.

What I am in the happy, zen-like, yet curiously energetic throes of is what is popularly known as the “runner’s high”. The runner’s high is a state of bliss achieved by athletes (not just runners) during and immediately following prolonged and intense exercise. It can be an extremely powerful, emotional experience. Many athletes will say they get it (and indeed, some would say we MUST get it, because otherwise why would we keep running 26.2 miles at a stretch?), but what IS it exactly? For some people it’s highly emotional, for some it’s peaceful, and for some it’s a burst of energy. And there are plenty of other people who don’t appear to get it at all. What causes it? Why do some people get it and others don’t?

By the end, some of these people will be blissful, some will want to hurl, and others will be both.


Well, the short answer is that we don’t know. As I was coming back from my run, blissful and emotive enough that the sight of a small puppy could make me weepy with joy, I began to wonder myself…what is up with me? As I re-hydrated and and began to sift through the literature, I found…well, not much. But what I did find suggests two competing hypothesis: the endogenous opioid hypothesis and the cannabinoid hypothesis.

The endogenous opioid hypothesis

This hypothesis of the runner’s high is based on a study showing that enorphins, endogenous opioids, are released during intense physical activity. When you think of the word “opioids”, you probably think of addictive drugs like opium or morphine. But your body also produces its own versions of these chemicals (called ‘endogenous’ or produced within an organism), usually in response to times of physical stress. Endogenous opioids can bind to the opioid receptors in your brain, which affect all sorts of systems. Opioid receptor activations can help to blunt pain, something that is surely present at the end of a long workout. Opioid receptors can also act in reward-related areas such as the striatum and nucleus accumbens. There, they can inhibit the release of inhibitory transmitters and increase the release of dopamine, making strenuous physical exercise more pleasurable. Endogenous opioid production has been shown to occur during the runner’s high in humans and well as after intense exercise in rats.

The cannabinoid hypothesis

Not only does the brain release its own forms of opioid chemicals, it also releases its own form of cannabinoids. When we usually talk about cannabinoids, we think about things like marijuana or the newer synthetic cannabinoids, which act upon cannabinoid receptors in the brain to produce their effects. But we also produce endogenous cannabinoids (called endocannabinoids), such as anandamide, which also act upon those same receptors. Studies have shown that deletion of cannabinoid receptor 1 decreases wheel running in mice, and that intense exercise causes increases in anadamide in humans.

Not only how, but why?

There isn’t a lot out there on HOW the runner’s high might occur, but there is even less on WHY. There are several hypotheses out there, but none of them, as far as I can tell, are yet supported by evidence. First there is the hypothesis of a placebo effect due to achieving goals. The idea is that you expect yourself to achieve a difficult goal, and then feel great when you do. While the runner’s high does have some things in common with goal achievement, it doesn’t really explain why people get them on training runs or regular runs, when they are not necessarily pushing themselves extremely hard.

Another idea is the idea that we need to run due to our history, that we evolved as persistence runners, outrunning animals not because we could run faster, but because we could run longer. In this case, any system that would allow us to continue running despite the pain of, say, bad knees, shin splints, or a slightly twisted ankle would be beneficial. The hypothesis supposes that the release of the endogenous opioids is for the purpose of killing pain and allowing us to run longer. There is no question that endogenous opioid release reduces our sensitivity to pain, but it’s very hard to prove this kind of hypothesis. I also wonder whether it’s a GOOD idea to experience the dulling of pain. It’s good for the race right now, but if you are being faced with the potential for chronic injury, that will be a major detriment to your hunting in the long term.

A third hypothesis is that the high may merely be the result of a partial brain shutdown. Because the runner’s high commonly occurs during glycogen depletion, the hypothesis is that the brain doesn’t have enough glucose on hand to keep it functioning normally while still controlling your workout, and you get a little loopy. I have never seen any support for this, though a PET study looking at brain glucose binding in athletes experiencing runner’s high might be able to determine whether this hypothesis holds any water.

Is there a finish line in sight?

Not for these studies. Scientists are still chasing the runner’s high, and there’s not yet a lot out there. Right now the evidence appears to support the hypothesis that endogenous opioid release and cannabinoid release in the brain triggers the effects, but of course, there’s lots of room in the brain for the answer to be more complicated, involving other neurotransmitters such as dopamine in the exercise-induced bliss. Even less known, however, is the why of the runner’s high. Maybe it’s exhaustion? Maybe it’s pain killing? Maybe it’s just to get us back out there the next time.

And now, if you’ll excuse me. I started this post after my run yesterday. But I finished it today and…I’ve got to get to the gym. It’s time to chase that runner’s high.

Galdino GS, Duarte ID, & Perez AC (2010). Participation of endogenous opioids in the antinociception induced by resistance exercise in rats. Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas / Sociedade Brasileira de Biofisica … [et al.], 43 (9), 906-9 PMID: 20802976

Boecker H, Sprenger T, Spilker ME, Henriksen G, Koppenhoefer M, Wagner KJ, Valet M, Berthele A, & Tolle TR (2008). The runner’s high: opioidergic mechanisms in the human brain. Cerebral cortex (New York, N.Y. : 1991), 18 (11), 2523-31 PMID: 18296435

Fuss J, & Gass P (2010). Endocannabinoids and voluntary activity in mice: runner’s high and long-term consequences in emotional behaviors. Experimental neurology, 224 (1), 103-5 PMID: 20353785

Sparling, P., Giuffrida, A., Piomelli, D., Rosskopf, L., & Dietrich, A. (2003). Exercise activates the endocannabinoid system NeuroReport, 14 (17), 2209-2211 DOI: 10.1097/00001756-200312020-00015

Hinton ER, & Taylor S (1986). Does placebo response mediate runner’s high? Perceptual and motor skills, 62 (3), 789-90 PMID: 3725516

Dubreucq S, Koehl M, Abrous DN, Marsicano G, & Chaouloff F (2010). CB1 receptor deficiency decreases wheel-running activity: consequences on emotional behaviours and hippocampal neurogenesis. Experimental neurology, 224 (1), 106-13 PMID: 20138171

Scicurious About the Author: Scicurious is a PhD in Physiology, and is currently a postdoc in biomedical research. She loves the brain. And so should you. Follow on Twitter @Scicurious.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. nthmost 1:15 am 03/12/2012

    I think the “runner’s high” is about as healthy a buzz as smoking crack.

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  2. 2. daedalus2u 4:58 pm 03/12/2012

    If you start to feel euphoric, that is a sign you are overdoing it. You should stop when you feel pain before you start to feel euphoric. People who don’t experience the runners’ high, don’t do so because they are wise enough to stop while they still have reserve metabolic capacity.
    My hypothesis is that the runners’ high is one aspect of a near death metabolic state. The state your body enters when you can’t afford to stop for anything, for example when you are running from a bear and to stop is certain death. I call that the Euphoric Near Death State, ENDS for short.
    When you are running from a bear, any injury short of death is infinitely better than being caught. Animals can run themselves to death. In the story of the first Marathon, the runner did exactly that, dropped dead after bringing word of the victory. Through force of will, you can overcome the pain, and run yourself to death too.

    We know that muscle can work itself to death. That is what a heart is doing during a myocardial infarction. The reason physiology is set up that way is because a beating heart with necrotic spots is infinitely better than a non-beating heart with no necrotic spots. If your heart stops beating, you are dead in a couple of minutes, a couple of seconds if it happens while a bear is chasing you.

    There is no emergency energy source that comes on line after near exhaustion. The reason you feel you have more energy is because ATP consumption by “housekeeping” pathways gets shut down, as in ischemic preconditioning. Those pathways can only be shut down for limited periods of time (if they could be shut down long term, they would be so organisms would have more ATP to devote to reproduction).

    This is also where the “energy” comes from when using stimulant drugs of abuse. There is no “extra” energy, there is diversion of energy from keeping you alive to doing what you want to do while you are on stimulants. That is why people on stimulants can easily die, as from PCP induced rages. That is also why people who do stimulants experience all the degenerative diseases at an accelerated rate.

    Then physiology induces the delusion that you can run forever. You can run “forever”, until you drop dead from exhaustion which is the same as “forever” in an evolutionary sense. I think this is the same euphoria as comes from stimulant drugs of abuse, from autoerotic asphyxiation, from solvent huffing, the euphoria of drowning and is the source of the “light” that some people see in near death experiences.

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  3. 3. scicurious 8:18 pm 03/12/2012

    I’ve never heard this perspective before, Daedalus. It’s interesting, but I’m not sure how well it works. After all, if the runner’s high is induced only in a near death state, shouldn’t a lot more runners and athletes be dying?

    In addition, the runner’s high does not require the experience of horrible pain or exhaustion, I certainly wasn’t pushing myself very hard when I last experienced it. You would also expect the high to be more often experienced when runners under or over hydrate, or fail to get needed nutrients while exercising, but people who take care to hydrate and carry and take energy sources with them also experience the runner’s high. While I do think the runner’s high may be a sign of decreases in brain glucose, for example (at least that’s one hypothesis which seems as reasonable as others), I’m not sure it’s so drastic as near death.

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  4. 4. rushil2u 5:23 am 03/13/2012

    Daedalus and nthmost, have you ever pushed your body till you felt the runner’s high? I have and do so every time I run or hit the road on my bike, which I do several times a week. As far as I can see, I’m a lot healthier than the other guys in my lab who prefer to sleep late and ride their motorcycles and scooters to work.

    It seems to me that a lot of fat, lazy folks out there are looking for a way to justify their unhealthy habits.

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  5. 5. rushil2u 5:26 am 03/13/2012

    Oh, and a myocardial infarction happening as a result of a heart beating itself to exhaustion? Go look it up on Wikipedia before coming here and embarrassing yourself!

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  6. 6. nthmost 2:00 pm 03/13/2012

    I have indeed felt the runner’s high, roughly 8 years ago when I was running because I thought cardiovascular exercise would have a positive effect on my physique (it didn’t).

    You (rushil2u) may be healthier than the guys who are sleeping late and not doing anything physical all day.

    But in comparison to people who are serious about their physical fitness and opt instead for heavy resistance training coupled with high-intensity interval training, people whose main form of exercise is steady-state cardio are sickly by comparison. Hormonal profiles of cardio-only exercisers don’t come out pretty.

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  7. 7. just me 8:37 pm 03/13/2012

    Dulling the pain is only part of the evolutionary rationale, Scicurious. The main reason for runners’ high was to amply reward ancient long distance running hunters for engaging in this vital yet highly taxing pursuit. (Sex is so gratifying for precisely the same reason.) Many athletes who are both runners and cyclers/ swimmers (like myself) insist that while all sports can provide equally strenuous workout, nothing compares with the euphoria induced by running. If cycling and swimming had played similar role in our evolutionary history, they’d also produce comparable highs…

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  8. 8. coreyjf 11:41 am 03/14/2012

    @daedalus2u doesn’t really match up with my experience. I typically run between 8.5 and 12.5 miles depending on how much time I can spare. Runner’s high typically kicks in for me around mile 2 or 3. I am no where near exhausted at that point. Even when I do my long runs 11 to 12.5 miles, I know I can go farther, but limited on time (have preschool age children at home and don’t get enough time with them during the week). If i am really hitting the point of exhaustion a 2 miles, it shouldn’t be so easy for me to go 6 times that distance.

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  9. 9. 4Learning 4:53 pm 03/14/2012

    Thanks for a thoughtful article. I ran a half marathon on Sunday and was impressed by how many of the 3,000 runners seemed to experiencing some kind of runners high. I know that since I have been running my mood is better, I have more energy, my MD says my heart sounds stronger than ever, I have the blood pressure of somebody twenty years younger. For me running feels good. I wonder if in part running helps us avoid the “non-running low.” This article from Duke does not address running specifically but the results are impressive in terms of treating depression. Thanks again. Enjoy you running.

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  10. 10. perfectly cromulent 5:11 pm 03/14/2012

    Maybe you’re on to something when you describe the experience as “zen-like”. Long bouts of exercize often involve counting, focus on breathing and rhythms, and zoning out and clearing the mind of extraneous thought. More or less exactly what meditation is. Perhaps some of the euphoria and clarity comes from achieving not just the physical state of exhaustion, but the mental state of “serenity”, or whatever you want to call it.

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  11. 11. clouston 7:06 pm 03/14/2012

    i wouldn’t know an endorphin if it bit me on the ass. Exercise is torture. Always has been. Any bright ideas?

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  12. 12. daedalus2u 9:20 pm 03/16/2012

    I am not saying that if you experience the runner’s high you are going to die, but you are (very likely) experiencing what is usually called over training, where you push yourself such that you harm your body instead of producing positive effects through exercise. If feeling good meant you were doing good things for your body, then how do over use injuries happen?

    If you are running from a bear, you want to be able to run until you drop dead from exhaustion. We know that people can do that. We know there has to be physiology that allows that to happen. What would that physiology have to look like? It would have to induce euphoria at near death metabolic stress because near death metabolic stress hurts like $%#&. When muscle dies, it sends out pain signals to let you know. You can over ride those pain signals, but the pain doesn’t get blocked unless endorphins are triggered to block the pain. If you are running from a bear and need to over ride those pain signals, that is what your physiology does.

    nthmost is correct. If you want to train for marathons you don’t run marathons. You do resistance training and interval training.

    A feeling of euphoria (like all feelings) is a very complex mental state where myriad nerves and other things are activating “just right”.

    We know that extreme metabolic states such as are experienced during autoerotic asphyxiation do cause euphoria. Why would we think that the euphoria of autoerotic asphyxiation is different than the euphoria of the runner’s high?

    I think that some people are experiencing something that is less euphoric than the runner’s high.

    There is no “emergency” energy source that kicks in after a certain degree of exhaustion. The number of mitochondria available doesn’t change in that time frame. The only possible place that “extra” energy can come from is turning stuff off that was consuming ATP before it got turned off. We know that happens in ischemic preconditioning. Why shouldn’t the “extra” energy that comes after a period of exercise be similar to the ATP conservation pathways of ischemic preconditioning?

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  13. 13. coreyjf 5:04 pm 03/21/2012

    @daedalus2u Why would you think the euphoria associated with auto-erotic asphyxiation is the same as runner’s high. There are lots of things that can cause euphoria including mediation. Running can have lots of similar qualities. On my run on Sunday I thought about your comments. When I started to feel the runner’s high I checked my GPS, I was at 2.2 miles. My heart rate was under target. My breathing was easy and steady, and I barely cracked a sweat. I was no where near exhausted and ran 13 more miles. Yes I know people that have run themselves to the point of deliriousness. But that is not runner’s high and not what most runners talk about.

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  14. 14. FitPro 7:41 am 05/22/2012

    Its a interesting argument and although I am not a massive fan of running myself, I do have respect for those who are passionate about it. I have put some of my own thoughts on the science behind it here

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