RIO DE JANEIRO (AP) — The reasons for triathlon’s burgeoning appeal are as varied as the sport itself.

—Fitness freaks looking for a new challenge.

—Millennials wanting something to hold both their interest and youthful physique.

—Gen Xers coaxed in by NBC’s annual Ironman competition in Hawaii.

The biggest factor, according to USA Triathlon, is the inclusion of the sport in the Olympic program.

“Looking at the causes for this growth, one must first turn their attention to the 2000 Olympic Games, triathlon’s first appearance at this international event,” the sport’s national governing body said in its most recent demographics report. “This elevated the publicity of the sport on the national level.”

Triathlon could get another big boost from the Rio de Janeiro Olympics, where two British brothers crushed the course on Copacabana Beach and where American Gwen Jorgensen, the two-time defending ITU world champion, is the gold medal favorite in the women’s race Saturday.

“When the races are being played in every bar in America, it’s impossible for it not to help,” suggested Patrick Lemieux, Jorgensen’s husband and operations manager, who added that he’s seen a giant leap in the sport’s awareness in the U.S. just since the 2012 London Games.

USA Triathlon touts itself as the world’s largest multisport organization, sanctioning more than 4,300 races and connecting with a half million members annually. It’s also the national governing body for duathlon, aqua-thon, aqua-bike, winter triathlon, off-road triathlon and para-triathlon. In addition to working on the grassroots level, it supports elite athletes competing in international events such as the International Triathlon Union world championships and the Olympics.

The 30-year-old Jorgensen was a late-comer to triathlon, recruited to the sport after an All-American track career at the University of Wisconsin, where she also was on the swim team.

Others start as soon as they can.

“I’ve been around the sport two-thirds of my life, since I was about 8 years old,” said Ben Kanute, a 23-year-old Olympian from Geneva, Illinois, whose father was a triathlete and helped organize the first kids triathlon at a health and wellness center near their home about the time the sport debuted at the Sydney Olympics.

Kanute said he started out swimming a couple of hundred meters, followed by a five-mile bike ride and a mile-long run, and he felt like those Ironmen he loved to watch on TV.

“I fell in love with the sport,” said Kanute, who hung with Alistair and Jonathan Brownlee on Thursday until the brothers broke free midway through the 6.2-mile run that followed a one-loop ocean swim and a steep 24-mile bike ride at Copacabana.

“It might just be that parents put them in there to blow off some steam, but’s it’s kind of the wow factor with triathlon,” Kanute said. “You get to swim, bike and run all in the same day. It’s pretty kid friendly.”

As they graduate to adulthood, triathletes typically start with the shorter sprints and move up to the Olympic-length races. Some move up to Ironman, which is 140.6 miles: a 2.4-mile swim, 112-mike ride and a marathon. There’s also half of that, the Ironman 70.3.

The Olympic races are over in an appealing two hours.

“And I think that’s the beauty of it,” Lemieux said. “In triathlon, you can do a sprint that’s one hour long, you can do an Ironman, which are eight hours for the fastest, 14 or 15 for others. So, the nature of the sport is that it can cater to anyone and I think that’s something that’s really appealing to people.”

Jay Brown, a 31-year-old counselor and track coach at Vista Peak Preparatory School in Aurora, Colorado, is a typical triathlete: he got into the sport in his mid-20s after souring on long runs and was hooked.

“The variety is the appeal. You have three sports instead of just running, which had gotten boring,” Brown said. “I was looking for something else to do and a friend suggested I try triathlon. I said I can do that. I just started swimming 50 meters in the pool and I didn’t even own my own bike. I used an old road bike.”

Soon, it was his passion. His training got more intense, his diet changed accordingly and as he gained the requisite energy and expertise, he also acquired his desired equipment, an aerodynamic bicycle. He even has a coach and a sponsor, Tabata Songs.

“A 23-year-old right out of college might not have the means to buy a triathlon bike, hire a coach and pay for travel and Ironman entry fees,” Brown said. “So, a lot of people get into it a little later.”

No matter their age or the discipline, triathletes find a close-knit community.

“Every triathlon that I go to just has a very cool vibe,” Kanute said. “There’s camaraderie because everyone knows how hard each person has trained to get there.”

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