Parkour is a physical activity which is difficult to categorize. It is not an extreme sport, but an art or discipline that resembles self-defense in the martial arts.According to David Belle, the physical aspect of parkour is getting over all the obstacles in your path as you would in an emergency. You want to move in such a way, with any movement, that will help you gain the most ground on someone/something as if escaping from it, or chasing toward it.Thus, when faced with a hostile confrontation with a person, one will be able to speak, fight, or flee. As martial arts are a form of training for the fight, parkour is a form of training for the flight. Because of its difficulty to categorize, it is often said that parkour is in its own category: "parkour is parkour."
An important characteristic of parkour is efficiency. A practitioner moves not merely as fast as he can, but also in the least energy-consuming and most direct way possible. Efficiency also involves avoiding injuries, short and long-term, part of why parkour's unofficial motto is être et durer (to be and to last).
Parkour is also known to have an influence on practitioner's thought process. Traceurs and traceuses experience a change in their critical thinking skills to help them overcome physical and mental obstacles in everyday life
http://en.wikipedia.org/wiki/Parkour
