First lady Michelle Obama talks with her brother Craig Robinson, an ESPN college basketball analyst, at the Aspen Institute's 2016 Project Play Summit in Washington. (Susan Walsh/AP)

More than 450 youth sports advocates, professional league officials and academic researchers gathered Tuesday in Washington to examine declines in participation among children linked to rising costs, parental pressures and increased emphasis on kids specializing in one sport.

As part of the day-long conference, Project Play, the Aspen Institute’s youth sports initiative, released a draft of its annual State of Play report, analyzing participation trends and highlighting innovative programs to address disparities.

Though the percentage of children ages 6 to 12 who regularly play team sports increased nearly 3 percent in 2015, to 40 percent, that is still below 2008 levels, when participation was 44.5 percent. Experts do not know whether the increase is just a momentary blip, whether it reflects an improving economy, or whether it is a demographic bump from more kids reaching sports-playing ages.

What is not receding is the huge disparity between the haves and have-nots.

“In 2015, only 38 percent of kids from homes with $25,000 or less in income played team sports, compared to 67 percent of kids from homes with over $100,000 or more in household income,” the Project Play report said.

First lady Michelle Obama and her brother, Craig Robinson, a former college coach, were among those at the conference who expressed concern that children across the country are being left behind by a system that favors families who can afford expensive travel teams and by bureaucracies that have drastically cut funding for physical education at schools.

“I’ve seen the difference,” said Obama, whose daughters have played competitive sports in Washington. “The disparities are amazing to me.”

An urgent fix is needed, Obama said, to make sure that all children have access to sports.

“Whatever the dollar figure is, as a society, as taxpayers, as corporate America, we should figure out how much that costs and then pay for it,” she said. “Period.”

The conference addressed other troubling trends. Talented kids who can afford travel teams are abandoning recreational programs, pressured by parents who view intense, year-round play in a single sport as an investment that will boost their child’s prospects for scholarships and college entry.

In reality, experts at the conference said, these parents are actually hurting their children’s chances, with study after study showing that specializing in one sport at an early age greatly increases injuries, some of which can end careers.

Neeru Jayanthi, a sports physician and director of tennis medicine at Emory University, said that even accounting for age and hours of sports played per week, young multi-sport athletes are at less risk for serious overuse injuries than those competing in highly specialized single sports.

Meanwhile, the kids left behind in recreational leagues get bored with poor levels of play and inexperienced coaches.

“There’s a real cultural challenge here,” said Ryan Eckel, vice president of brand at Dick’s Sporting Goods. “Very, very quickly there’s pressure to start deciding if this is going to be a real thing or a fun thing.”

Even the phrase “rec league” has become problematic. “People associate it with frivolity and not being serious,” Eckel said.

Unstructured play has disappeared from many children’s lives. Obama and her brother discussed their sports days growing up on the South Side of Chicago, recalling a game they called “chase” and playing Nerf basketball in the living room, using lamp shades as hoops.

They played for hours and hours, entertaining themselves. Youth sports today is more regimented, they said.

“Right now, if you put a bunch of kids out in a field today,” Obama said, “I don’t think they would know what to do.”

Conference speakers and the Project Play report highlighted innovative programs to bolster youth sports, many of which are funded and run by professional sports leagues and teams concerned that their talent and fan pools will dry up.

The U.S. Tennis Association is pushing Play Days — short, low-pressure matches without results or rankings that are hosted by schools, parks and youth centers.

Major League Baseball, with a $30 million investment, is introducing a program called Play Ball in 140 U.S. cities.

“Whiffle ball, stickball, skills competitions like Pitch, Hit & Run, home run derby, and just playing catch in the backyard are at the center of the effort,” the report said, “a response to the sport increasingly being dominated by organized leagues and travel team ball that can ask a lot of families in terms of financial and time commitments.”

And more than 45 national sports groups, including the USTA, MLB, NFL, PGA, and NHL, are backing an effort to encourage multi-sport play.