The hottest new event in distance running sounds like a riddle. The fastest runner doesn’t always win. It has no finish line. And it can drive adults to eat baby food. Behold the backyard ultramarathon, or “backyard ultra.” The rules are simple: Run one 4.167-mile loop in an hour. Then do it again and again, each hour on the hour. The race keeps going—sometimes for days—until there’s only one person standing. There’s no limit on how far the races can go. 📷: Ilana Panich-Linsman for WSJ, Getty Images, Reuters, Bo Shelby, Jennifer Edwards Reporter/Host: Rachel Bachman Producer: @jacob.ohara #backyardultra #marathon #running #race #wsj