Editor’s note: This article was originally published March 13, 2014

A documentary about an aging ultra-marathon runner will get one final screening in Austin this Saturday.

"The Immortalists" focuses on 62-year-old molecular biologist and long-distance runner Dr. William Andrews, who runs at least one 100-mile race each month in an effort to stop the aging process. Andrews calls the practice "longevity running," because he believes it lengthens his telomeres, the caps at the end of chromosomes that wither away with age.

He is studying telomeres and the enzyme telomerase at his biotech company, Sierra Sciences, and thinks he can develop a pill to make human cells immortal.

Andrews and his wife Molly Sheridan, also an ultra runner, ran a 50K on their way to the premiere of the film, directed by David Alvarado and Jason Sussberg, during the SXSW Film Festival last weekend at the Stateside Theatre. That’s a relatively short run for Andrews, who attempted a 138-mile high-altitude race in the Himalayas in 2010, as recounted in the film.

This weekend’s final screening is scheduled for 11 a.m. March 15 at the Topfer Theatre, 1510 Toomey Road.