RICHMOND - Virginia lawmakers voted Tuesday to require that all children in public elementary and middle schools participate in at least 150 minutes of physical activity a week to help fight the growing problem of childhood obesity.

The change would be most significant in kindergarten through fifth grade, where experts estimate that fewer than 10 percent of schools in Virginia meet the standard.

"The facts are, children are getting bigger and bigger,'' said Del. John M. O'Bannon III (R-Henrico), who introduced the bill in the House. "There are tremendous downstream consequences of that. I think this is a fair trade-off."

But some school district officials oppose the looming requirement - to be implemented in 2014 - saying it could extend the school day, lead to cuts in arts and music classes, or increase costs because additional teachers would be needed.

"Schools can't be expected to solve all of society's problems," said Fairfax Superintendent Jack D. Dale, who lobbied against the legislation.

In Fairfax County, the state's largest school district, students at 139 elementary schools are required to take at least 60 minutes of physical education a week. Prince William County requires 90 minutes a week for students at 55 elementary schools.

Both Michelle Obama and Virginia's first lady, Maureen McDonnell, have made getting children to eat healthier and exercise more a top priority.

The General Assembly's bill follows a new law by the D.C. Council, which last year approved school nutrition and physical education standards that were among the strictest in the country. The measure called for 150 minutes of physical education in elementary schools and 225 minutes in middle schools. (Maryland does not have similar requirements.)

In Virginia, the Republican-led House of Delegates passed the bill Tuesday, 65 to 31. The Democratic-led Senate voted for the bill last week, 37 to 2. The bills differ slightly - the House exempts kindergartners who attend school half-days and does not require daily activity - but the Senate is expected to accept the House version. Neither bill allows recess to be included in the 150 minutes.

A spokesman for Gov. Robert F. McDonnell (R) said he would review the legislation before deciding whether to sign it into law.

The Virginia Education Association, which represents thousands of teachers across the state, opposes the measure but supports the goal to provide more physical activity for children.

Robley S. Jones, the VEA's director of government affairs, said schools' budgets have been cut by 15 percent since 2008 and are being asked to do more. He said that if the state wants to implement the program correctly, it should provide districts with money for additional teachers or facilities. "There is a cost to this," he said.

In 2008, state legislators passed a bill recommending 150 minutes of activity in schools, but most did not abide by the recommendation.

Liz Payne, Fairfax's coordinator for health and physical education, said this year's legislation will mean elementary students will have to more than double their physical activity. But, she said, it will not affect middle schools, where students take more than 150 minutes of physical education a week.

Keith Imon, Prince William's assistant superintendent for communication and technology services, said that children do need to get more physical activity but that he doesn't know how the bill can be implemented without additional costs. The county would have to increase physical education for elementary school students as well as sixth- and seventh-graders, who take about 112 minutes of physical education a week.

Del. R. Steven Landes (R-Augusta), who voted against the bill, called it an unfunded mandate.

"You and I both know the school systems already have to do a lot with not all the funding that they believe they need now," Landes said. "The goal is laudable. The implementation is going to be a concern."

But O'Bannon said additional money was not provided because any elementary or middle school teacher can teach physical education so schools will not have to hire new teachers.

Legislators also agreed to recommend - but not mandate - 150 minutes of weekly physical education for high schools.

The bills were introduced by two doctors who serve in the General Assembly - Sen. Ralph S. Northam (D-Norfolk), a pediatric neurologist, and O'Bannon, a neurologist.

The groups supporting the bills because of the mounting costs to society of obesity included the Virginia chapter of the American Academy of Pediatrics, the Virginia Heart Association, the American Cancer Society, the American Heart Association, the American Diabetes Association, the National Association of State Boards of Education, and the Centers for Disease Control and Prevention.

"We are facing a crisis in Virginia and across the country," said Cathleen S. Grzesiek, director of government relations for the American Heart Association. "It's time for the state to take this bold step."

Thirty-one percent of Virginians ages 10 to 17 are overweight or obese, according to a 2007 survey conducted by KidsCounts.org. Extra pounds lead to a greater risk of diseases such as Type 2 diabetes, high blood pressure, heart disease and high cholesterol.

"Some people think it's maybe a little too much to ask the schools to do what this bill suggests," said Del. James M. Scott (D-Fairfax). "But I think that because way too many of our kids are overweight, we have an obesity problem that way overwhelms any problems the bill causes. I think parents needs a little help."