CAMBRIDGE — Standing poolside in sleek, black swim trunks and a lemon-colored swim cap, Christian Farmer was about to find out if the second time would be a charm.
At his first triathlon last September, Farmer surprised family and friends by notching a third-place finish with little training and no previous experience.
“He was still on training wheels,” said Colleen Wade, Farmer’s mother, who waited nervously for her son to plunge into the Massachusetts Institute of Technology pool. “But now, he’s got the bike down,” she said.
For his first attempt, it wasn’t too shabby. Especially for a 5-year-old.
“He had a great experience with the first triathlon,” said Wade, whose son is now 6 and trains at the Hockomock Area YMCA. “He found that instant gratification.”
He was one of more than 400 youngsters ages 5 to 15 who paddled, pedaled, and pumped in the first ever New England Kids Triathlon hosted at MIT’s Johnson Athletic Center on Sunday morning.
Once the territory of serious athletes and exercise fanatics, triathlons are permeating mainstream exercise culture, thanks to organizers and proponents who are spreading the swim-bike-run gospel to younger audiences.
The sport has a variety of draws, said Tom Gildersleeve, chief volunteer for the nonprofit group Kids Triathlon Inc., that organized the New England event.
Gildersleeve said some of the youngest triathlon converts hail from competitive swimming backgrounds, where many children burn out by middle school, tired of swimming’s lonesome, individual nature.
Others come for the challenge, or the confidence that completing the event inspires.
Shelley Maroney, 21, was standing against the rope line on Vassar Street where the helmeted competitors whizzed by on bicycles, some grinning, some grimly focused, while others hunched and huffed.
Maroney, who taught a series of triathlon training sessions at the Taunton YMCA, turned out to watch her students.
As a child, she said, she would have embraced a chance to swim, bike, and run competitively.
“Just to finish a triathlon, for a 6-year-old, is a big deal,” Maroney said.
But training was a luxury to many who had leaped into the event late.
Nate Ruffin said he and his daughter, Natalia, found out about the competition only two weeks ago, but decided to give it a whirl anyway.
“She’s only 10, but she’s in a phase where she’s trying anything,” said Ruffin, who lives in Randolph with his wife, Michelle, and their 7-year-old son. “I’m hoping she finishes and likes it.”
Other youngsters committed earlier.
Scott Foster of Marlborough said he asked his son, André, if he wanted to train for the 2013 race, but the 8-year-old pushed to compete sooner.
“He said, ‘no, Dad, I want to do it this year,’ ” said Foster. “I think I’m probably more nervous than he is.”
To expand the sport nationally, Kids Triathlon Inc. has partnered with scores of YMCA centers across the country and with a half-dozen NFL franchises in six major cities.
If all goes according to plan, the nonprofit said it will introduce races in at least four new markets next year.
While the distances are a fraction of what they can be in adult triathlons, the nonprofit tailors the scale to challenge all participants: Children ages 11 and older swim 200 yards, bike 6 miles, and run 1 mile. Those age 10 and younger compete at half those distances.
The feat was enough to make Tony Povoas reel, though.
He drove from Sandwich to see his 5-year-old grandson, Benjamin Brodsky, compete, and was amazed at the athleticism exhibited by many of the competitors at such early ages.
“I couldn’t do it in a car, boat, and motorcycle,” Povoas said. “To focus that much at 5, 6 years old, it’s pretty amazing.”