For adults, it can take weeks – maybe months – of training to get ready for a triathlon. But if you already spend your spare time swimming, biking and running -- for fun, not for the workout -- the three-sport race comes a little more naturally.

"Triathlon is a perfect sport for kids," says Dave Deschenes, a coach with Tampa Bay Tri Sports. "As a kid, what do you do in the summer? You run around the neighborhood, you go to the pool, you jump on a bike."

Children are participating in triathlons in record numbers. For some, it's just a more structured version of what they do on a typical weekend. Others tackle the race with the same practice and commitment they would apply to soccer, Little League and other traditional youth sports.

Since 2006, the year USA Triathlon began requiring memberships for its sanctioned events, the number of youth athletes has climbed by more than 23,000 nationally. Last year, 37,238 7- to 17-year-olds were members of the triathlon organization.

That age group makes up about a quarter of the total USA Triathlon membership, which also is rising and surpassed 140,000 last year.

Ava Sykes surprised her parents three years ago when she told them she wanted to do a triathlon. She was 6.

Neither of her parents had competed in one, although her father bikes. But she had seen her cousin compete and wanted to do the same. Her mother, Leigh Ann, says Ava is a bit of a daredevil and likes to try new things, so they let her sign up for "Tri If You Dare" in Seminole, unsure of how she would do.

"She really took to it," Leigh Ann Sykes says.

Now 9, the Largo fourth-grader competes in a dozen triathlons a year. She trains with a coach and team through Tampa Bay Tri Sports, performing speed drills and working on her form. Usually, she concentrates on one sport per day, but occasionally she does "brick" workouts, where she may bike and run, for example, back to back.

Last year, Ava became the 8-year-old girls' IronKids national champion, and she will compete again this month in nationals in Iowa. She says she's shooting to compete in the Olympics some day.

Ava says she likes how team members cheer for each other; and although the biking comes easiest to her, none of the sports seems too hard.

"It's really fun to do," she says.

Deschenes says Florida children are especially lucky, because they can play outside for most of the year. The tri calendar is filled almost every weekend from March to November.

That likely contributes to the large number of triathletes in the state. Florida has the second-highest number of adult and children USA Triathlon members nationally. Only Texas has more. Youth membership in Florida surpassed 3,600 last year, up from 1,220 in 2006.

Deschenes has seen that growth reflected in the Tampa Bay area.

Two years ago, Deschenes, who was coaching preteens and teens, merged programs with coach Karen Quilty and her 6- to 11-year-olds and Michael Benedict's developmental program in New Tampa. They've gone from about 20 participants to 45.

Tampa Bay Tri Sports now is one of 17 sites nationally that USA Triathlon designates as a high performance team, which means it has training programs equipped to develop world-class athletes. It serves 6-year-olds through teenagers, starting with the basics and a heavy emphasis on fun.

Once children gain experience, they work on getting acclimated to open-water swims, learn about bike safety and riding with other people surrounding you, and the proper form and technique for running.

But newcomers should keep it simple.

Dr. John Gross, a St. Anthony's physician who is board-certified in family medicine and sports medicine, says triathlons should start as an extension of kids' play.

"Triathlon is a way to organize that play together in a race," he says. "Up until you get in your teens, it's not really about winning the race – it's about getting out there and having fun."

Gross, a triathlete and medical director for Ironman Florida and the St. Anthony's Triathlon says St. Anthony's "Meek & Mighty" race for ages 7 and older is a nice entry point for children.

Competitors do the swim portion at North Shore Pool – not in Tampa Bay like the adult participants – and the run and bike route is wide and open without a lot of turns. The distances vary depending on age.

The medical staff is rarely called on for the children's race, Gross says, and most kids are conditioned enough through their daily play that they don't need formal training for small races. Parents should have their children's bikes checked before the race and make sure they have a good helmet. A good pair of running shoes is also a worthwhile purchase, Gross says.

Like most sports, triathlon participation can cost as much as parents are willing to invest. Entry fees and travel expenses will depend on how many races kids register for and where they are. Coaching at Tampa Bay Tri Sports runs $50 per month for two organized practices a week.

Deschenes says he has seen girls riding pink Barbie bikes with training wheels and tinsel hanging off the handlebars as well as kids on $3,000 bikes. But beginner triathlons are welcoming places, he says, featuring a pool swim, a bike ride on a road closed to traffic, and a run through a park or baseball field.

Children who play organized sports are likely to have the fitness they need to finish a race, but Gross says if they want to become more competitive in triathlons they can practice putting the different segments together. Swim a little bit and then bike, he says, or try going from the bike to a short run.

Gross recommends that young athletes measure how many minutes they spend on an activity rather than the how far they go.

Injuries from overuse can happen, such as shoulder aches from swimming or knee pain while running, but Gross says kids usually are good about telling their parents when something hurts. Parents should listen to their children, he adds, and not push them too hard.

Remember, just going out there is an accomplishment. Gross says the surge in interest in triathlons is a refreshing change from hearing about so many children fighting obesity.

"It definitely warms my heart to see more kids involved in this," Gross says. "This is a way to get them away from the TV and video games."