Mike Fremont, 82, of Glendale, runs through Sharon Woods park. (Gary Landers/The Cincinnati Enquirer)

Hours after he ran the Boston Marathon, Mike Fremont encountered three men wearing Marathon shirts on an airport shuttle April 18. He congratulated them and mentioned he, too, had competed.

They didn't hide their surprise.

"They were like, 'You were in it?' " Fremont said. "And I said, yep! I was the oldest guy in the marathon."

Fremont, 82, started running at age 37 and hasn't stopped since. The avid athlete has run 37 marathons, including 11 Bostons, and was not at all pleased that 85-degree heat slowed him down at the 109th running.

"I ran a 5:45. Terrible," Fremont said.

Greg Hayes, communications assistant for the Boston Marathon, said Fremont was the oldest male finisher by two years. The eldest female finishers were both 71.

Fremont's running career began 45 years ago after the death of his first wife, Jacqueline. Left to raise three small children, he turned to running to relieve stress. Every day he'd come home from work and run a bit and "it would take the tension away," he said.

Five years later, he branched out into marathon canoeing, an activity he and his wife, Marilyn Wall, enjoy together. They were on their way to Florida to pick up their car, which had their canoe on top, when Fremont met the three marathon runners on the airport shuttle.

A 35-year volunteer for preserving and restoring rivers, Fremont still spends much of his week working for Rivers Unlimited in Wyoming. During his 16 years of "retirement," he has been busy with conservation efforts and exercising.

He said his fitness regimen (9 miles every other day) and diet (vegetarian) have helped him stay fit.

As one of few male runners in his age group in any race, winning his division or beating the generous qualifying times for other races is usually pretty easy. To qualify for Boston he had to run a five-hour marathon, which is a half-hour slower than his average.

Fremont has no plans to stop training. His goal is to reach the "ultimate age group," where, in 10 years, he hopes to better the world marathon record set by 92-year-old Fauja Singh. Singh finished the Toronto Marathon in 5:40 in 2003.

Fremont finished the Flying Pig Marathon in 4:28 last year and is considering running again today - unless it's too hot.

"I'm tired of running hot marathons. I don't have to," Fremont said. "I don't have anything to prove."