Bernie Sanders has not made it a secret that he was once a competitive distance runner, but as the presidential race heats up, that fact has been getting increasing attention.

At a recent Democratic Presidential Town Hall in Des Moines, Iowa, Sanders, 74, said this on CNN when asked about his athletic accomplishments: “I was a very good long-distance runner, I would say not a great runner, but I was captain of my track team, won a number of cross-country meets, and certainly won a whole lot of races. Good, very good, not great.”

Sanders’s assertions have led reporters to do some digging into his past. Their research has revealed that Sanders was indeed a strong runner for James Madison High School in Brooklyn. He was good enough that his name occasionally appeared in The New York Times.

In May, Sanders told CNBC that he believes his best mile time is 4:37. Sanders has repeated that assertion elsewhere, but no one has yet been able to uncover printed proof of his time. But as runners know, not all of one’s best times wind up being printed in a newspaper.

According to The New York Times, Sanders did finish third in mile at the Brooklyn Public Schools Athletic League Track & Field Championships on May 21, 1957, when he was 15 years old. The winning time in that race was 4:37, but only the winning times were printed in the newspaper.

Little is known about Sanders’s current fitness regimen, and his campaign did not respond to a request for comment on his running exploits, past or present. But in November, a video posted on YouTube of Sanders running to catch a train, showed that while he may no longer be a fast miler, he’s still pretty light on his feet. 

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All of the attention on Sanders’s running exploits begs the question: Do any of the other candidates run?

Republican Mike Huckabee, 60, who ended his presidential campaign last week, was the most accomplished marathoner in the presidential race. Huckabee famously lost more than 100 pounds, took up running, and was featured in a 2005 Runner’s World article. He ran four marathons between 2005 and 2006, with a best of 4:26:05 at the 2006 Little Rock Marathon. The last time Huckabee made national headlines for his running was when he announced plans to run the 2008 Boston Marathon, before pulling out with a knee injury.

Huckabee had surgery to remove a bone chip from his knee November 25, 2015, and Huckabee’s campaign did not respond to a request for comment on his running or current exercise routine.

Republican Marco Rubio, 44, a former college football player, claims that he is the fastest presidential candidate running in 2016. That could very well be true, over short distances at least. He has maintained over the years that he ran 4.65 for the 40-yard dash at his fastest, which would put him on par with some NFL running backs.

As with Sanders’s mile, there is no YouTube video to prove it, but Rubio clearly has an athletic background. He attended Tarkio College in Missouri on a football scholarship for one year, and he reportedly works out on a regular basis. Rubio’s campaign did not respond to a request for comment.

Republican Rand Paul’s campaign confirmed in an email to Runner’s World that his exercise routine includes some running.

“Senator Rand Paul exercises every day, and running is certainly part of his routine,” Paul's communications director, Sergio Gor, wrote without elaborating further, before Paul ended his campaign last week.

In April, Paul, 53, tweeted a mid-run selfie that further supported his running background. He even had “safety runner” shirts for men and women so supporters could safely promote their candidate while running around town.

If the other candidates do any running, it’s not something that they’ve broadcast widely. And none of the other campaigns responded to requests for comment about their candidate’s exercise routine.

This article originally appeared on RunnersWorld.com.