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
IAAF World Half Marathon Championships IAAF World Road Running Championships. Aside from the name change, the significant difference was the distance of the race, changing from a half marathon to a 20 kilometres road race. The 20 km race featured only at the 2006 edition, and the half marathon distance returned for the 2007 World Road Running Championships. On 29 November 2007, the IAAF announced that the name of the competition would revert to its original title of the IAAF World Half Marathon Championships, beginning with the 2008 IAAF World Half Marathon Championships in Rio de Janeiro, Brazil on 12 October 2008. This competition should