Birkebeinerrennet (lit. The Birkebeiner race) is a long-distance cross-country ski marathon held annually in Norway. It debuted in 1932 and has been a part of Worldloppet since Worldloppet's inception in 1979. The Birkebeinerrennet is one of three races held under the Birkebeiner moniker, the other two being Birkebeinerrittet (bicycling) and Birkebeinerløpet (cross-country running). The race was inspired by a notable journey made by the Birkebeiner loyalists Torstein Skevla and Skjervald Skrukka to save the infant heir to the Norwegian throne, Håkon Håkonsson, in the winter of 1206. Researchers at the Manchester Metropolitan University found that the metabolic cost for modern ski models is about 2.5 J/kg*m as compared to about 5 J/kg*m for ski models dated 542 AD. They also estimated maximum cross country speed for the 542 AD ski to 5 m/s, compared to about 12 m/s for modern cross country skis; for long distance skiing (several hours) results were 3 and 7 m/s respectively. This corresponds to about 5 hours for the original 1206 AD Birkebeiner flight. Race The race starts at Rena and ends at Lillehammer, a distance of . The number of participants has been steadily increasing each year, and for the 2011 race, the limit was set at 16,000. The following aid stations are present: Skramstadsetra, 9 km Dambua, 15 km Kvarstad, 28 km Midtfjellet, 35 km Sjusjøen, 40 km History Origin The Birkebeinerrennet has been held since 1932, and commemorates a trip made by the Birkebeiner loyalists Torstein Skevla and Skjervald Skrukka to save the infant heir to the Norwegian throne, Håkon Håkonsson, in 1206. All participants carry a backpack weighing at least 3.5 kg, symbolizing the weight of the then one-year-old king. The inaugural edition was won by Trygve Beisvåg. An own class for women was established in 1976. Until 1991, the start city was alternated between Lillehamer (finish at Rena) and Rena (finish at Lillehamer). The last time that Birkebeinerrenet started at Lillehammer, the start was located on the site where the Lysgårdsbakken ski jumping arena were built for the 1994 Winter Olympics. Special 2002 FIS World Cup Race In 2002, the race was included as the last event in the FIS World Cup. The World Cup class was won by Thomas Alsgaard and Anita Moen Guidon finishing in 2:24:08.7 and 2:43:39.1, respectively, faster than all records set prior to 2012 for men and prior to 2015 for women. However, the participants