You've probably heard the ancient tale of Pheidippides, an Athenian herald in handmade sandals who ran 25 miles home to the Acropolis from the Battle of Marathon in 490 B.C., thereby reporting Greek victory over the Persians. You may not know he accomplished this shortly after sprinting the 150-mile round trip from Marathon to Sparta in search of foreign aid. Pheidippides can thus lay claim to being the world's first ultrarunner, meaning anyone who runs farther than the traditional 26.2-mile length of a marathon. It should be noted, sadly, that he croaked, "Rejoice, we won!" and died on the spot.

Such are the risks associated with pushing one's body beyond the mundane. Micah True, born Michael Hickman in Boulder, Colorado, died in March 2012 while ultrarunning in New Mexico's Gila Wilderness. The autopsy revealed cardiomyopathy. "That's an enlarged heart," explains Garry Harrington, promoter for a documentary called Run Free: The True Story of Caballo Blanco. "That's common among long-distance runners and endurance athletes. It's an occupational hazard."

True gained minor celebrity from an appearance in Christopher McDougall's 2009 book Born to Run, but he first grew enamored with ultrarunning in the 1980s and '90s in Central America. The Tarahumara people of northwestern Mexico run extremely long distances in street clothes and handmade huaraches, at an elevation of over 10,000 feet. "They run as transportation, mostly," says Harrington. "They don't have any other way to get around. There's a lack of roads, lack of money, lack of vehicles."

Seattle-based documentarian Sterling Noren created Run Free in collaboration with True's last girlfriend, Maria Walton. It calls True the sobriquet he was given by Copper Canyon villagers, who dubbed him "White Horse" for his complexion and flowing blonde locks. "What makes me proud," Walton says, "is that you hear his voice. It couldn't be more organic and more beautiful. People see a different side of Micah that the book doesn't portray, and Micah himself wouldn't open up to that much."

Run Free will screen at the Olympia Film Society, followed by a Q&A with the filmmakers. It pays tribute to a remarkable athlete and the 50-mile "Ultra Marathon" he launched in Copper Canyon. True "had a simple little vision," recalls Walton. "He just wanted to run with these beautiful people of Mexico, and he didn't want their age-old tradition of running to die. Their name means the light-footed ones. They're running people."

Run Free: The True Story of Caballo Blanco, Tues., Oct. 6, 6:30 p.m., Capitol Theater, 206 5th Ave. SE, Olympia, $12-$15, 360.754.6670

Sunday, Oct. 18, 6:30 p.m., The Grand Cinema, 606 S. Fawcett Ave., Tacoma, $12-$15, 253.593.4474