The Backyard Ultra World Championship format requires runners to start a 6.706-kilometer lap every full hour, in other words the difference between how long it takes them to do a lap, and 60 minutes, can be had as rest time.

At the same time, early finishers must wait until the full hour before starting their next lap. In short, the highest number of laps a competitor could do in 24 hours would be 24.

The competition for one team continues as long as at least two competitors are still running. When a team is down to one runner, that person can complete a "victory lap" to clock up the team's final lap tally.

The overall result is determined by the total number of laps completed by all runners in each team.

Teams are by country, with a maximum of 15 members per team.

As if that were not enough, the race is being done virtually – competitors do not need to travel anywhere and can adjust start times to their time zone, and run the set laps in their own country.

In the case of Estonia, this was all done at a course in Keila, just outside Tallinn.

As of Sunday, four Estonians from the team of 15 had dropped out.

11 of the 61 teams still had all their runners in the game, and had completed the maximum possible 160.9 kilometers (ie. 6.706 x 24), or 100 miles, by day's end.

Estonia's total number of completed laps stands at 340 after the first day, placing them 20th as noted.

In last year's event, the U.S. was the most resilient, putting in 860 laps in the 24 hours, followed by Belgium (788 laps) and Australia (744).

The official event site is here.

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