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You may have heard an exercise-mad friend talk about getting a “runner’s high” – a feeling of euphoria after going for a run1. If you’re not a runner yourself, you may have thought this was crazy talk, but it’s biology – that “high” your friend gets after running is produced by endorphins1.   

What are endorphins?

Put simply, they’re small proteins manufactured in your brain that act as natural painkillers2. Endorphins work by binding to the same opioid receptors in your nervous system as the active ingredients in opioid painkillers, like morphine2. They also allow your body to produce excess dopamine, a chemical associated with pleasure – hence that “high”2.

Endorphins as painkillers

Your body releases endorphins in response to pain or when it feels under threat3. This could be a real threat, or an imaginary threat – it reacts in the same way3. Endorphins have a powerful painkilling effect, even more potent than morphine3.

The opioid conundrum

The problem with opioid painkillers is that the medication and your body’s natural endorphins compete for the same receptors so the longer you take opioid medication, the less your body produces endorphins2. That means you need more medication to dull your pain and so a cycle of addiction can begin2.

Boost your endorphins

Studies have explored whether deep-tissue massage and acupuncture can trigger your body to release endorphins because there is a degree of pain involved, but they’ve been inconclusive3. One group of researchers suggested it could be because you’re too relaxed in those environments and that you need the combination of pain and being under stress to trigger the endorphin release4. Exercise, on the other hand, has been found to trigger the release of endorphins and could even be a natural way to get relief from pain – although the type of exercise and the intensity play a role3.While moderate-intensity exercise tends to be more enjoyable, high-intensity and endurance exercise are best for triggering the release of pain-relieving endorphins because you feel like you’re exerting yourself more, which triggers a stress response4. It’s best to consult your healthcare provider before starting a new exercise programme.


1. Leuenberger, A. Endorphins, exercise, and addictions: A review of exercise dependence. Impulse: an Undergraduate Journal for Neuroscience. (2006).
2. Sprouse-Blum, A.S. et al. Understanding endorphins and their importance in pain management. Hawaii Med J69(3), 70–71 (2010).
3. Pilozzi, A. et al. Roles of β-Endorphin in Stress, Behavior, Neuroinflammation, and Brain Energy Metabolism. Int. J. Mol. Sci. 22, 338 (2021). 4. Saanijoki, T. et al. Opioid Release after High-Intensity Interval Training in Healthy Human Subjects. Int. J.Neuropsychopharmacol.43,246–254 (2018).