" Some sources point to the origin of a runner's high being increased endorphin production as a result of exercise. Running injuries There are many injuries associated with running (due to it being a high impact activity) . Common injuries are "runner's knee" (pain in the knee), shin splints, pulled muscles (especially the hamstring), "jogger's nipple" (soreness of the nipple due to friction), twisted ankles, and Iliotibial Band Syndrome. The most common running related injuries are due to over-use. Repetitive stress on the same tissues without enough time for recovery or due to improper form or muscle imbalances, leads to many of the above. Generally these can be minimized by warming up beforehand, wearing proper running shoes, improving running form, performing strengthening exercises, and getting enough rest. There is a very strong consensus among the running and scientific community that all of those can be very effective in minimizing or recovering from running injuries. Country Cross Logo Running Another injury prevention method that is very commonly recommended in the running community, but is actually controversial is stretching. While stretching is often recommended as a near requirement to avoid running injuries, the relevant medical literature does not represent as much of a consensus that it is effective. "

" Any running that covers a distance further than a marathon is called ultrarunning; the event is an ultramarathon. Such events can be measured in distance (for example, 100 kilometers) or by time (whoever has run the farthest after 24 hours). Examples include the London to Brighton run in England which is just over 54 miles (87. 085 km), the Comrades Marathon run between Pietermaritzburg and Durban in South Africa which is about 89 km (55. 3 miles), and the Badwater Ultramarathon between Death Valley and Mount Whitney in the United States which is 135 miles (215 km). Road running is unique among athletic events because in many cases first time amateurs are welcome to participate in the same event as members of running clubs and even current world-class champions. Professional road racing's governing body is the IAAF. Art Clip Country Cross Running Competitors from around the world participate in what is dubbed the "elite" races for cash prizes. Kenyans and Ethiopians are renowned for their skill and it is rare for a race's top finishers not to include competitors from these countries. "