Ai
Created page with "== Overview == Trail running is a sport-activity which combines running, and, where there are significant gradients, hiking, that is run "on any unpaved surface". It is similar to both mountain and fell running (also known as hill running). Mountain running may, however, include paved sections. Trail running normally takes place in warm climates, or on good paths, or tracks which are relatively easy to follow, and does not necessarily involve the sig..."
