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
Marathon earlier. In 2014, an estimated 550,600 runners completed a marathon within the United States. This can be compared to 143,000 in 1980. Today marathons are held all around the world on a nearly weekly basis. For a long time after the Olympic marathon started, there were no long-distance races, such as the marathon, for women. Although a few women, such as Stamata Revithi in 1896, had run the marathon distance, they were not included in any official results. Marie-Louise Ledru has been credited as the first woman to complete a marathon, in 1918. Violet Piercy has been credited as the