OAKLAND -- First Lena Russell-Zazueta swam the length of a 25-yard pool. Next she hopped on an exercise bike for 10 minutes of leg-burning fun. Finally she ran a few laps around the outside of the 75,000-square-foot downtown Oakland YMCA building.

By 10 a.m. Saturday, a time when some of her peers were likely engrossed in the SpongeBob SquarePants marathon on Nickelodeon, Lena, 7, had earned a medal in the youth triathlon, part of the Healthy Kids Day festivities at the Downtown Oakland Y.

Her favorite part of the triathlon?

"Everything," she said.

That's what Kathleen Gushoney, executive director of the Downtown Oakland YMCA, likes to hear. Approximately 1,900 YMCAs nationwide -- including several in the East Bay -- participated in Healthy Kids Day, a free community event that encourages activity and healthy habits in school-age children.

While specific events may have varied from one YMCA to another, the message was the same.

"It's a day to get kids and families moving together," said Gushoney, who anticipated about 500 people would attend Saturday's event. "It's about exposure to activities they might not have tried before and it's in a really fun and supportive environment."

Although the YMCA's youth programs are for all kids, Gushoney considers them especially important for obese children.

"We have worked with kids who have been diagnosed as obese at Children's Hospital in Oakland," she said. "We work with them all year long, and when we see them competing in the triathlon, and we know that when they got to us originally they had a hard time breathing, a hard time walking, that's probably the most exciting moment of the day."

Berkeley's Donna Russell and her daughters, Lena and 11-year-old Emma, were attending their second Healthy Kids Day.

"They love the whole thing," Russell said. "My kids have always been athletic, but this encourages them to keep doing more. They swim, they bike, they do Zumba, they do all kinds of stuff."

In addition to the youth triathlon, the Downtown Oakland YMCA offered a move-athon, a 10-station activity that featured jumping jacks, frog hops, high-five lunges and a bounce house. After the youth triathlon, the indoor pool was used for casting lessons, giving kids a feel for what it's like to fish.

A small army of volunteers cheered kids on at the triathlon and move-athon. While the vocal support may have helped Lena run faster, it had another effect on her as well.

"It makes me kind of shy," she said.

Contact Gary Peterson at 925-952-5053. Follow him on Twitter at Twitter.com/garyscribe.