Runner’s high is a colloquial term that refers to a neurochemicl reaction in which a rush of endorphins is released during a long workout. The high concentration of endorphins leads to a feeling that is at once relaxed and energized. Although popularly associated with marathon runners, the feeling is also reported by wrestlers, skiers and others who participate in extremely physical sports.
A similar sensation can result from another type of neurochemical reaction that occurs when a fear is successfully conquered. This natural high can be addictive, leading those who experience it to seek out ever bigger thrills. Those who become addicted to the feeling are sometimes known as adrenaline junkies.