What The Heck Is An Endorphin – And Is It Really The Cause Of The ‘Runner’s High?’


Whether you’re a runner or not, you’ve likely heard of the term, ‘Runner’s High.’ This pertains to a word that is also quite commonly thrown around – Endorphin. Despite the common use of the word, most people and athletes don’t really know what it is. In full transparency, despite researching a lot of different areas for the UESCA Running Coach Certification, I didn’t know all that much about it either… So let’s dig in!


The word, Endorphin is the combination of parts of two words, Endogenous and Morphine. Endogenous means to originate within an organism and Morphine is an opiate that acts on the central nervous system to reduce pain.


Endorphins are hormones produced naturally by the body and in respect to athletics, they are produced in response to pain. They are produced by both the central nervous system (CNS) and the peripheral nervous system (PNS). There are three main types of endorphins:

  • A-Endorphin
  • B-Endorphin
  • Y-Endorphin

Endorphins block neurotransmitters. They are often considered natural pain killers as they activate the same opioid receptors in the brain that reduce pain.

In the CNS, the endorphin binds to a receptor that as a result of blocking a specific neurotransmitter, increases the production and release of dopamine. Dopamine is a neurotransmitter (chemical) within the brain that when released, can cause feelings of euphoria – hence, the ‘Runner’s High.’ While this type of high is generally viewed as a good thing, drugs such as cocaine and heroin cause large spikes in dopamine, which causes the user to want more and more of it.

In the PNS, endorphins released from the pituitary gland bind to receptors and this binding inhibits pain signals of peripheral nerves by blocking a particular neurotransmitter.


According J. Kip Matthews, Ph.D, a sport and exercise physiologist, most studies done regarding endorphins look at blood plasma endorphin levels and thereby deduce that if endorphin levels rise in the blood, then endorphin levels also rise in the brain. However, this might not be the case as Matthews states that B-endorphins cannot pass through the blood-brain barrier. Therefore, as endorphins in the brain are what would cause the feeling of euphoria, might there be something else that is responsible for the ‘runner’s high?’

In a 2015 study by Fuss et al., Fuss noted that running increases levels of endorphins as well as a neurotransmitter called, Anandamide. Unlike B-endorphins, Anandamide can pass through the blood-brain barrier. Anandamide binds with cannabinoid receptors. In Fuss’s study, the ‘runner’s high’ effect in mice was the result of anandamide.


The exact duration and intensity required for someone to have a runner’s high is very much individually-based. Some sources have noted that the release of endorphins does not occur until around the 60 minute point. It should also be noted that some people do not experience a runner’s high when running (or working out).


The reduction of pain and the ‘high’ that runners (and other athletes) get from the release of endorphins is a good thing. This is also one of the main reasons why exercise is often used as a treatment method for anxiety and depression.


Like the example of cocaine and heroin noted above, for some individuals the reduction in endorphins when not exercising results in the craving for the ‘high’ and thus can lead to exercise addiction.


It is likely that both exercise-induced endorphins and anandamide both contribute to a ‘runner’s high.’ Regardless of the source of one’s runner’s high, the fact that exercise can help with anxiety/depression, reduce pain and for some, get a euphoric feeling is quite an amazing thing!


Rick Prince is the founder/director of United Endurance Sports Coaching Academy (UESCA), a science-based endurance sports education company. UESCA educates and certifies running, ultrarunning and triathlon coaches (cycling coming soon!) worldwide on a 100% online platform.

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Fuss J1Steinle J2Bindila L3Auer MK4Kirchherr H5Lutz B3Gass P2. “A runner’s high depends on cannabinoid receptors in mice.” Proc Natl Acad Sci U S A. 2015 Oct 20;112(42):13105-8. doi: 10.1073/pnas.1514996112. Epub 2015 Oct 5.

Goldstein A, Lowery PJ (September 1975). “Effect of the opiate antagonist naloxone on body temperature in rats”. Life Sciences17 (6): 927–31. doi:10.1016/0024-3205(75)90445-2PMID 1195988.

Boecker H, Sprenger T, Spilker ME, Henriksen G, Koppenhoefer M, Wagner KJ, Valet M, Berthele A, Tolle TR (November 2008). “The runner’s high: opioidergic mechanisms in the human brain” (PDF)Cerebral Cortex18 (11): 2523–31. doi:10.1093/cercor/bhn013PMID 18296435.

Li Y, Lefever MR, Muthu D, Bidlack JM, Bilsky EJ, Polt R (February 2012). “Opioid glycopeptide analgesics derived from endogenous enkephalins and endorphins”Future Medicinal Chemistry4 (2): 205–26. doi:10.4155/fmc.11.195

Rick Prince

Rick Prince

Founder/Director of United Endurance Sports Coaching Academy (UESCA).

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