This Sunday, May 4th, runners will toe the line at the ungodly hour of 4 a.m. at the Sports Authority Field to simultaneously race against runners in 32 locations around the globe—1p .m. in Alanya, Turkey, 10 p.m. in Auckland, New Zealand, and for Californians, 3 a.m.—for the first ever Wings For Life World Run. Among the professional athletes lining up in Denver include the Broncos’ DeMarcus Ware, snowboarder Louie Vito, skier Chris Davenport, freeskier Grete Eliassen, and ultrarunner Karl Metzler.

The motivation for getting up so early is a simple one: 100 percent of proceeds go to the Wings for Life, a foundation that funds cutting-edge research for curing spinal cord injuries, a familiar and devastating risk that comes with some of our favorite mountain and adventure sports.

Plus, this race is unlike any you’ve run: There’s no finish line. Instead, once the runners take off, a “Catcher Car” will give chase 30 minutes later, accelerating at intervals in sync with the other racecars around the world. You’re finished when it passes you and soon after, a shuttle will scoop you up to bring you back to the start. If you run a 10-minute mile, you’ll make it 5k and be out for 50 minutes, a 7-minute mile will get you to 10k and you’ll be on your feet for 1 hour 10 minutes. Winner is whoever can get the furthest before they’re caught. Pretty cool, huh?

Registration ended on April 27th, but there are a limited number of first-come, first-serve spots available. Head down to Original Brooklyn’s (2644 W. Colfax Ave.), from 12 p.m. to 5 p.m. on Saturday to snag one.