Endorphins and the Runner's High

How Endorphins Impact Your Body

Exercise can cause a release of endorphins.
Exercise can cause a release of endorphins. Peopleimages/Getty Images

Often referred to as the body's natural pain relievers, endorphins are biochemical substances your body makes that have some of the same properties as substances made from opiates. Released into your body as a response to a variety of situations like pain or stress, endorphins help to reduce pain and can bring about feelings of euphoria, calm, relaxation, and well-being.

How Endorphins Work

Endorphins are classified as "endogenous opioid polypeptides" and there are over 20 different kinds. They're proteins that are produced by the pituitary gland and hypothalamus during strenuous exercise, as well as in response to pain, excitement, and other stress stimuli. Acupuncture can also stimulate your body to produce endorphins.

If they're produced in response to pain, endorphins are distributed throughout your nervous system where they interact with your opiate receptors to reduce your perception of pain. These neurotransmitters not only reduce pain, they also make us feel good, boost our immune systems, aid with memory, balance our appetites, contribute to the release of sex hormones, and help regulate our body temperature. So when we're laughing, stressed out, engaging in a sexual activity, exercising, or in pain, you can bet endorphins are being released into our bloodstreams.


Endorphins were first discovered in 1974 by two separate groups of independent investigators, both of whom were utilizing and studying the brains of animals. Scientists John Hughes and Hans W. Kosterlitz, both from the University of Aberdeen in Scotland, first identified and isolated endorphins from the brain of a pig. Simultaneously, Rabi Simantov and Solomon Snyder, both from the United States, identified endorphins in a calf brain. It was also discovered around this time that these endorphins in the human body, as well as the body of many animals, are capable of producing morphine-like effects.

The Painkilling Effect

The results of this varied research enabled neuroscientists to determine that the human brain contains endorphins to limit pain, which your pituitary gland releases when your body is under stress or feeling pain. These endorphins interact with receptors to reduce the overall perception of pain by allowing more dopamine to be released into the body. The effects of this process are similar to the use of a drug such as morphine.

Thus, if an artificial painkiller such as morphine is introduced into your body, it has an effect on the naturally occurring endorphins. As such a painkiller is introduced, it occupies more of your brain’s pain receptors. Your body senses this, and in return, less naturally-occurring pain reducers are produced, a balancing technique your body creates. However, when the artificial source is removed, many pain receptors become empty. This causes a craving for endorphins, often in the form of narcotics, and this is how addiction can begin.

The Runner’s High

For some individuals, running a long distance can cause a sense of euphoria that's comparable to the high you can get from drugs. The reported sensations of this runner’s high include feelings of extreme peace, a sensation of floating, bliss, euphoria, and increased pain tolerance. Some people also call the good feelings they have after a long workout a runner's high.

This runner’s high has been credited to an increased level of endorphins in the brain. Though endorphins are consistently released to your body as you run and certainly increase in your bloodstream, research has shown that they may be too big to move from your blood into your brain, so they may not actually be the chemical that's responsible for creating a runner's high.

According to a 2015 study on mice, what might be behind these feelings instead is a neurotransmitter called anandamide, an endocannabinoid that, along with endorphins, is released into your blood when you run. Since both chemicals are also released in mice when they run, the study was done with mice that ran on a wheel, using medications to block the effects of each chemical. When endorphins were blocked, there was no change in the symptoms of runner's high like calm, pain tolerance, and sedation. However, when they blocked anandamide, all the runner's high signs went away. Thus, the researchers found that cannabinoid receptors, and specifically the release of anandamide, may be the key to the feelings behind a runner's high.

The bottom line is that it may be a while before scientists figure out exactly which chemicals are responsible for a runner's high, but research increasingly points to endocannabinoids rather than endorphins.

Long-Term Benefits

Thanks to brain chemicals, if you're a habitual long-distance runner, your anxiety level is likely much lower than the average person's and you may have less sensitivity to pain too. The neurotransmitters dopamine, serotonin, and norepinephrine are also boosted when you exercise, which can account for the good feeling many of us get when we're done with a workout.

If you're just getting started with running, you too can build up this level of calm, relaxation, pain tolerance, and feelings of well-being by consistently engaging in moderate to intense levels of exercise. In fact, it's often the reward of those good feelings we get after a long run, which seem to be heavily influenced by endocannabinoids like anandamide, that inspires us to do it again and again, despite the risk of injury and the time and energy running takes.

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