Wearing dripping bathing suits and wide grins, the swimming competitors lined up and bowed their heads to accept their Northern Virginia Senior Olympic gold, silver and bronze medals Friday morning at Claude Moore Recreation Center in Sterling.

The swimmers chatted cheerfully beside the center’s large competition pool, and several posed for photographs with family members. But one swimmer was less than pleased with his performance.

Phil Case, 84, thought of the many gold medals he has at home. “A bronze medal,” he said, shaking his head. “I’m not happy. I can do better.”

Friday’s swimming events were among the more than 50 events in the 31st annual Northern Virginia Senior Olympics. The games took place across the region from Sept. 7 through Thursday. Swimming and track and field were among the most popular events, but there were quieter activities, too, such as bridge, cribbage, dominoes and Wii bowling.

Case, a resident of the Greenspring retirement community in Springfield, has always been drawn to swimming and driven by the chance to compete, he said.

“It’s good to have a goal, and this is an extra good reason to work out and stay in shape,” Case said. “And it’s fun. You meet great people.”

For about 725 registered participants, 50 and older, the games are a welcome opportunity for competition and camaraderie. As baby boomers age, the population of retired people in Northern Virginia has soared. About 12 percent of the state’s population is older than 65, and seniors say they’re looking for more opportunities to stay active, healthy and involved in their communities.

By 2030, people older than 65 will make up about 20 percent of Virginians, according to the University of Virginia’s Weldon Cooper Center for Public Service.

Judy Massabny, communications director for the Senior Olympics, works on senior activities in Arlington County. She expects even more Northern Virginians to sign up next year. This year’s games drew about the same number as last year, the 30th anniversary of the games, she said.

The event benefits from the steadily increasing recruitment pool, she said. Moving to Florida isn’t in the cards for many Washington area residents, even if they’ve retired. “The folks who have lived and worked here in Washington, they tend to stay here,” Massabny said.

Arlington’s senior programs are in high demand, and some, such as fitness classes, have waiting lists, she said. The county recently opened the Arlington Mill Community Center, a $35 million, five-story facility that is expected to draw many seniors.

Northern Virginia’s Senior Olympics have more than doubled in size since the games began in 1982, said Betsy Bailey, 76, who has been on the organizing committee since 1986 and jokes that she is the event’s unofficial historian.

The variety of events helps keep participation up; the lineup is designed to offer something for everyone, regardless of ability, she said. This year’s oldest male competitor is 97, and the oldest woman is 103, Bailey said.

Prince William County’s senior population has had the largest increase in the region in recent years. In 1990, 3 percent of the county population was 65 or older. It rose to nearly 5 percent in 2000 and to more than 7 percent in 2011, according to U.S. Census figures, a jump of 48 percent in the past decade. Developers in Prince William have built several age-restricted communities for seniors, drawing thousands.

Like the Senior Olympics, the Heritage Hunt retirement community in Gainesville offers many activities for those 55 and older, and has a golf course, said William Pierce, 81, who has lived there for 10 years. The community is marketing to the region’s increasing number of seniors, Pierce said. “You can come here and live your dream,” he said.

The burgeoning retirement communities and senior centers across Northern Virginia are the prime marketing targets for the games, Bailey said. The Northern Virginia games are intended to be fun and to offer friendly competition. The state and national Senior Olympics require participants to meet certain qualifications.

Paul Gesswein, 77, has lived in Loudoun County for more than 20 years. When he moved to the area, he said, there were not many services and resources for seniors. Since then, the senior population in Northern Virginia has exploded, and the number of retirement communities has followed suit. “There are so many activities and outlets,” he said, including the Senior Olympics. “We’re going in the right direction.”

Gesswein said he takes swimming seriously, but he’s not in it for the medals.

“There’s very little ego here. Tt’s more of a congratulate-your-competitor type situation,” he said. “It rejuvenates you. It makes the older generation much younger.”

Carol Morello and Patricia Sullivan contributed to this report.