The science behind a ‘runner’s high’

The pain-relieving effects of exercise were described as ’fascinating’ and brought to mind anecdotal evidence of ‘ecstatic states… and anaesthesia’. Later, these effects, along with sedation and reductions in stress and anxiety, became popularly known as ‘runner’s high’, though the term is too imprecise for some experts.

Despite scepticism about the term itself, scientists became absorbed in understanding what caused these effects, focusing on the possible contributions of endorphins – opiate hormones that hit the same receptors as painkillers like morphine. ‘Getting your endorphin hit’ entered the lexicon of sports enthusiasts. What hasn’t filtered through to the mainstream, though, is the fact that theories around endorphins have fallen out of favour in recent years. Meanwhile, new theories have materialised around another group of natural chemicals: lipid molecules called endocannabinoids that have an important influence on our brains. Much as endorphins are considered as our internal opiates, endocannabinoids can be thought of as the body’s natural cannabis, with their receptors including the same one associated with the psychotropic effects of tetrahydrocannabinol (THC) from the marijuana plant.