With regard to Kilian Jornet's FKT, I'll quote an entry from trailrunningsoul.com in its entirety. It discusses the route, Jornet's record and some history. Jornet's run was fully supported by his corporate sponsor (Salomon), complete with video footage via helicopter (videos are accessible via trailrunningsoul.com.)
After winning last year’s Ultra-Trail Mont Blanc, breaking the record of the race at only 20 years-old, Spaniard Kilian Jornet faces now new challenges out of the regular racing calendar. His official sponsor, Salomon, has nicknamed it “The Kilian’s Quest”, and will take him to try to break the John Muir Trail current record in September. But he had his immediate challenge closer to home: the Island of Corsica.
The GR20 is one of the most famous footpaths in Europe which crosses nearly the complete island from North to South. 118miles and nearly 69000 feet of accumulated height on a clearly waymarked terrain which for most people takes around 15 days of hiking. The northern part is the most steep and rocky part while the southern is considered easier and with a lower altitude.
Early morning on Monday, Jornet kicked off his challenge with a clear goal in mind: to beat the current course record. In 2006 Pierrot Santucci run the distance in 36h 53', setting a very high mark. There were two more attemps in 2008 to break the record: Vincent Delebarre (2004 UTMB winner) in June and Jean-Louis Cinqui two months later had to quit before covering the full distance. With this in mind, Kilian Jornet left at 3:55AM on Monday from Calenzana with only 1.5 pounds of weight and a record to break.
He decided to start fast his attempt with 1 hour 30 ahead of schedule after 12hours. At 4.10PM local time he passed Pietra Plana almost 2 hours ahead of schedule and after 16 hours of running, he got his first deserved break. He stopped for 20min at Vizzanova, taking pastas and drinking a lot of water, as temperatures were really high in Corsica. That’s when Pierrot Santucci, who had been advising the young runner on this challenge, welcomed Kilian, together with many local runners.
The plan was to use 4 pairs of shoes. He started with the Speed Cross, which he switched for the XT Wings S-Lab (a new prototype also from Salomon), and which he would change again during Tuesday morning. Another change of gear during the challenge was the Exo calf, which he switched for the Exo tight when the fatige was starting to wear him down.
At midnight he was at 5250 feet, on his way to the refuge de Prati at an amazing 600m/hour after 20 hours of running. With the most rocky part behind him, he kept a good pace during the night hours, with local runners running along and helping keep the right path. Though the pace was getting slower (as planned), he was still ahead of schedule.
At 10:00am local time he left the Bavella pass to tackle the last major climb. He then left his GPS beacon at the refuge Paliri. He was suffering quite a lot… and he even didn’t want to run with it in the first place. He finally run througth the last 12Km of downhill to Conca, where he arrived at 12:59PM with the new record set at 32hours, 54 minutes and 24 seconds.
Kilian knew the GR20 on vacation with his family when he was 3. 18 years later he made it one of his greatest accomplishments in his (short) life as a runner.