The “Endorphin Rush” of Runner’s High “Runner’s high” is the rush of euphoria that many people experience after intense aerobic exercise, especially running or cycling. In an ingenious experiment by German neuroscientist Henning Boecker and his colleagues (2008), elite male runners were injected with a radioactively tagged chemical that bonded to opioid receptors in the brain. After two hours of endurance running, PET scans showed the highest levels of natural endorphin production in brain regions known to be involved in positive emotions. The scans also showed that endorphin activity was positively correlated with subjective experience: The more intense the euphoria experienced by the individual runner, the higher the level of endorphin activity in his brain.
Kirby Lee/Image of Sport-