The soldiers of ancient Sparta were known for being among the world's fiercest troops. Today, those who challenge themselves to a Spartan Race are known for being among the fiercest athletes. Held across five continents, these Reebok-sponsored events pit runners against obstacles both natural and manmade, like climbing walls, mud pits, barbed-wire crawls, and fire jumps. In the race literature's own words, these professionally engineered races are meant to "get people back to their primal roots ... to run, jump, climb, and sweat."

That said, athletes of all calibers are welcome to sign up, as courses range in length to accommodate varying skill levels (adults are ages 14 and over). Resources such as WODs and free group workouts help determined athletes up their pre-race game, no matter what their starting level is. There's also the Spartan Kids division for children who have a competitive streak and haven't yet outgrown playing in mud, and Junior and Youth Spartan Races for ages 5 to 10 years of age and 11 to 13. The races are so popular, Spartan Races has even started ranking athletes who have participated in multiple events.