parkour dangers???

Question

ways to prevent them

Answer 1

(park-or) an urban activity where a traceur completes a 'run', overcoming obstacles on the route with a variety of gymnastic and acrobatic moves including elements such as jumps, vaults, and wall runs.

Parkour (also called Le Parkour, PK, or free running) is a sport in which participants attempt to clear all obstacles in their path in the most fluid manner possible.
Parkour is a physical activity that is very difficult to categorize. It is definitely not an extreme sport, but an art that resembles martial arts. However, most traceurs are content to simply put parkour in its own category: "parkour is parkour".

The most characteristic aspect of parkour is efficiency. The basic meaning of this is that a traceur must not merely move as fast as they can, but move in a way that is the least energy-consuming and simultaneously the most direct. In addition, since parkour's unofficial motto is être et durer (to be and to last), efficiency also involves avoiding injuries, short-term or long-term.
http://en.wikipedia.org/wiki/Parkour

all the best.