Many people associate a runner’s high, or the sense of euphoria felt after exercising, with endorphins. But experts now suspect another molecule may be at play.

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If you’ve ever completed a long run and felt like you could keep going a few more miles, you may have experienced a runner’s high.

This sense of euphoria helps athletes feel relaxed and calm. It can also help shield against pain from the long bout of exercise, at least temporarily.

But not everyone who runs or exercises will feel this brief moment of bliss.

Keep reading to find out why a runner’s high occurs. This article will also review what’s responsible for this feeling and why it may not be as easy to experience as you might hope.

A runner’s high is a brief, deeply relaxing state of euphoria. Euphoria is a sense of extreme joy or delight.

In this case, it occurs after intense or lengthy exercise. Often, people who experience a runner’s high also report feeling less anxiety and pain immediately after their run.

Not everyone who runs or exercises intensely will get a runner’s high, however. It’s difficult to measure “euphoria” because the experience is subjective. But what we do know is that it’s likely rare.

Plus, you may need to run for several miles at a time to reach the point where a runner’s high could occur. For many people, this distance might not be easy or possible.

So if you complete a lengthy jog and you don’t feel like you could begin your race again, you’re probably not alone. But good for you for taking that healthy run anyway.

A runner’s high isn’t the only possible benefit of running or exercising. Indeed, there are several physical benefits caused by the chemicals released when you’re running, and they’re not all related to your cardiovascular system.

Running and aerobic exercise release a flood of endorphins into your blood. Endorphins are often called the “feel-good” chemicals because they produce feelings of happiness and pleasure.

They also help you feel less pain while you’re running. That can act as a natural pain reliever, helping you endure longer periods of exercise.

For decades, scientists believed endorphins were responsible for a runner’s high. It makes sense — they do have a great deal of beneficial effects.

But in recent years, research has revealed that endorphins may not have much to do with it after all. Instead, new research points to another type of molecule: endocannabinoids.

These molecules act on your endocannabinoid system. This is the same system that’s affected by tetrahydrocannabinol (THC), the active compound in cannabis.

Like endorphins, exercise releases endocannabinoids into the bloodstream. If you feel euphoric or deeply relaxed after a run, these molecules may be the responsible party.

Endorphins are neurochemicals released naturally by your body. They’re made by your central nervous system and pituitary gland.

Endorphins act on the same part of your brain as opioids like morphine. That’s why they’re called the “happy” chemicals. They’re released during exercise or in times of pain or stress, as well as in response to eating or sex.

Endorphins, however, are large molecules. Of course, they’re microscopic and can’t be seen by the naked eye — but when compared with other chemicals in the body, they’re considered large.

And their size prevents them from crossing the blood-brain barrier. This is an impediment in the body that keeps your brain safe from certain pathogens and molecules. Endorphins are one of those molecules that can’t cross over to your brain.

This means endorphins can’t actually be responsible for a runner’s high — it must be something else.

That something else may be endocannabinoids. These molecules are small enough to cross the blood-brain barrier, and they act on receptors in your endocannabinoid system. This is the same system that’s activated by THC, the most active compound in cannabis.

A type of endocannabinoid called anandamide is found at high levels in the blood of people who’ve recently completed a run. Some research suggests anandamide may trigger a runner’s high. This results in short-term psychoactive effects like:

  • reduced anxiety
  • euphoria
  • a feeling of calm

However, research that looks at how the brain and body respond to endocannabinoids after exercise is quite limited.

In fact, the most significant study was conducted on mice in 2015. It’s unclear if the same results occur in humans. Research in this area is still ongoing.

A runner’s high is not a guarantee for everyone who laces up and takes off to pound pavement. Other benefits are more likely and just as beneficial in many ways.

Some of the most common benefits of running include:

A runner’s high is a short-lasting feeling of euphoria or bliss that occurs after exercise or running. Not everyone who runs or exercises will experience a runner’s high — but those that do may find themselves exercising to chase that exquisite feeling.

People who experience a runner’s high also report feeling less anxiety and reduced pain, and they say they feel calmer and happier after exercise.

Your body produces a number of chemicals while you’re running, and researchers are beginning to understand the many ways your body may respond to exercise. This includes sensations like a runner’s high.

However, it remains unclear why some people experience a runner’s high and some do not. It’s also unclear what you can do to make a runner’s high happen. But even without feeling this euphoric state, exercise like running is a healthy choice for most people. And that’s a feel-good reason as any.