A year ago, Reston, a place with hundreds of triathletes and its own triathlon each September, had no triathlons for kids. Now it has two.

On Sunday, Reston Association and the YMCA will host its first Reston Kids Triathlon. More than 200 athletes ages 6 to 14 will swim, bike and run on a course starting at Ridge Heights Pool at 8 a.m. and ending on the track at South Lakes High School.

 Children ages 6 to 8 will swim 50 meters, bike 1.1 miles and run 0.6 miles. Children 9 to 11 will swim 100 meters, bike 2 miles and run 1 mile. Children 12 to 14 will swim 200 meters, bike 4 miles and run 1.4 miles.

In May, the inaugural Be Amyazing Triathlon - organized by South Lakes student group Amy's Amigos in memory of friend Amy Boyle, who died of a brain tumor in 2006 - also took place on a similar South Reston course.

That race's registration filled up quickly, as did signups for the Sunday's race. Reston Association Parks and Recreation Director Larry Butler, the organizer of Sunday's race, says he was not surprised.

"Triathlon is one of the fastest-growing sports in the country," he said. "If you look on one of the race calendars, there are two other kids' triathlons in Northern Virginia in the next two weeks. Two or three years ago, you never would have seen that.

"I hope this will be an annual event, and that Amy's Amigos will continue theirs too," he said. "There is clearly a demand for it."

Butler said he has been impressed with the enthusiasm of young athletes as they took part in race clinics this summer. While many participants are already seasoned athletes, some are new to all facets of the sport, said Butler.

At Laurel Learning Center, which has a large number of low-income students,  26 kids have been training as part of the camp day. The center even brought in a stationary bike trainer to boost training.

Butler says the triathlon was able to offer 50 race entry scholarships to low- income kids in the community. Donations from sponsors also included 30 bikes and helmets, which awardees can keep.