Trail running is an individual sport where competitors run across terrain that includes mountains, deserts and forests.

Trail running differs greatly from running in that it is performed on hiking trails that traverse varying terrain like hills, mountains, deserts, and forests; these trails are often inaccessible by road except at the trail head. It is common for trail runners to ascend and descend thousands of miles during a trail run.

In competition, the goal of trail running is to finish the race in the shortest amount of time.

Common distances for trail races range from 5 to 30 kilometers. Each race determines their distance and particular rules regarding the kinds of equipment runners are allowed to carry during the race.

Trail Running Shoes

Trail races are commonly equipped with aid stations supplying food and beverages every 5 to 10 kilometers. Nevertheless, runners in trail races, particularly longer ones, usually carry their own water and food along the course.

While trail running is an individual sport, training is commonly done in small groups. Runners, out of necessity, always carry their own equipment during training runs. Navigational skills are also important during training runs because runners are covering a large, undefined area and veering of course is typical.

http://en.wikipedia.org/wiki/Trail_running