Long-distance running only the placing is of importance. Other less popular variants such as fell running, trail running, mountain running and tower running combine the challenge of distance with a significant incline or change of elevation as part of the course. Multisport races frequently include endurance running. Triathlon, as defined by the International Triathlon Union, may feature running sections ranging from five kilometres (3.1 mi) to the marathon distance (42.195 kilometres, or 26 miles and 385 yards), depending on the race type. The related sport of duathlon is a combination of cycling and distance running. Previous versions of the modern pentathlon incorporated
Half marathon Half marathon A half marathon is a road running event of 21.0975 km (13 mi 192½ yd)—half the distance of a marathon. It is common for a half marathon event to be held concurrently with a marathon, using almost the same course with a late start, an early finish or shortcuts. If finisher medals are awarded, the medal or ribbon may differ from those for the full marathon. The half marathon is also known as a 21K, 21.1K or 13.1 miles, although these values are rounded and not formally correct. A half marathon world record is officially recognised by the