text: Motivation A feature of such activities in the view of some is their alleged capacity to induce an adrenaline rush in participants. However, the medical view is that the rush or high associated with the activity is not due to adrenaline being released as a response to fear, but due to increased levels of dopamine, endorphins and serotonin because of the high level of physical exertion. Furthermore, recent studies suggest that the link to adrenaline and 'true' extreme sports is tentative. Brymer and Gray's study defined 'true' extreme sports as a leisure or recreation activity where the most likely outcome of a mismanaged accident or mistake was death. This definition was designed to separate the marketing hype from the activity.Eric Brymer also found that the potential of various extraordinary human experiences, many of which parallel those found in activities such as meditation, was an important part of the extreme sport experience. Those experiences put the participants outside their comfort zone and are often done in conjunction with adventure travel.
  Some of the sports have existed for decades and their proponents span generations, some going on to become well known personalities. Rock climbing and ice climbing have spawned publicly recognizable names such as Edmund Hillary, Chris Bonington, Wolfgang Güllich and more recently Joe Simpson. Another example is surfing, invented centuries ago by the inhabitants of Polynesia, it will become national sport of Hawaii.