While parkour is a new sport and little research has been done, an early study suggests that parkour may be safer than most common sports. The study found parkour injuries occurred at a rate of about 5.5 incidents per 1000 exposures. This incident rate would then place the risk of training parkour to be about as risky as women’s volleyball or men’s baseball at 4.9 and 5.8 incidents per 1000 exposures respectively. This suggests that parkour may be several times safer than football (35.9), wrestling (29.6), and soccer (18.8). If fact, this suggests that parkour is even safer than field hockey (7.9). (source)
Research seems to suggest parkour is exceptionally healthful. In particular, on study said that parkour shows how lifestyle sports can “contribute to physical health, wellbeing, community and civic engagement, appealing to groups of male and female participants not engaged by traditional sporting activities, and particularly team games. (source)” So, parkour not only helps develop well-rounded athleticism and physical fitness without the danger of repetitive injuries, it also develop strong character, self-confidence, and social skills.
Parkour was developed in the suburbs of Paris in the 80s and 90s. To read an excellent history of the sport, check out “Breaking the Jump” by Dr. Julie Angel.