Actors in “Marathon ’33” demonstrate what happens when you try to dance forever.

If you thought Olympic athletes had to work hard, consider what the characters in the American Century Theater’s production of “Marathon ’33” are up against. Based on the experiences of writer June Havoc, the show recreates a dance marathon, a nationwide phenomenon during the Great Depression.

People cutting a rug for as long as they can sounds harmless, but the longest ones went for more than 4,000 hours, says artistic director Jack Marshall, who can’t believe the conditions that contestants (who were mostly poor, unemployed and starving) suffered through.

They got a 15-minute break once an hour, which included the time it took to get on and off the dance floor — a recipe for hallucinations and breakdowns.

The physical demands led to leg cramps and painful blisters. And if the dancers developed issues that demanded medical attention, such as a tooth that needed to be extracted, a doctor came onto the dance floor. “They used no anesthesia, and the line judge was there to say, ‘Keep dancing,’” Marshall says.

Although the show portrays a 3,000-hour-long marathon, Marshall’s cast members dance for only 2½ hours. Still, they have to survive 15 musical numbers, a tap competition and two “sprints.” (“When [judges] wanted to eliminate people, they told [the contestants] to race walk around the arena until somebody dropped,” Marshall says.)

One cast member ruptured a disc trying a common dance marathoner trick from the ’30s: They would tie handkerchiefs around their wrists to hang their arms around their partner’s neck and get dragged around while they snoozed.

The government eventually banned these dangerous events, so “Marathon ’33” is as close as you can get to experiencing one today. And that’s probably a good thing.

The Gunston Arts Center, 2700 S. Lang St., Arlington, Va.; Fri. through Aug. 25, $30-$35; 703-998-4555,