Backyard Ultra is a lap race which means that the participants must run a lap of 6.7 kilometers every hour - as long as they can.
The Swedish record is 68 laps, which means a distance of almost 460 km in 68 hours.
The first Backyard Ultra competition in Sweden was organized in 2015 and now today the competition was held for the first time in Karlshamn.
Charlie Bergström from Sölvesborg has run some Backyard Ultra races before and his record is 25 laps, that is almost 170 km.
- You can get quite tired in the wee hours but it seems to be nice weather both today and tonight so we will see what it lands on this time, says Charlie Bergström who is one of a total of 14 participants in the race.
Watch the participants run in the clip above.