PALM BAY, Fla. — Around the country, as schools try to squeeze in every minute for lessons that could help raise scores on standardized tests, recess is on a slide that began decades ago, educational researchers say.

Instead of having unstructured free time, thousands of Florida elementary students now are required to stretch at their desk, walk laps after lunch and watch videos on healthy eating habits.

The change is a result of a new state law that mandates 150 minutes of physical education each week for students in kindergarten through fifth grade — more than four times the amount the average elementary student received last school year. To squeeze the extra minutes into an already busy day, many school officials said they had no choice but to reduce recess or drop it entirely.

Virtually everyone, from parents and principals to teachers and health and education experts, support the law's intent. But like most sweeping reforms and unfunded mandates, unintended consequences abound.

Until this year, Florida elementary students typically received 15 to 20 minutes of recess two to five days a week.

Approved by health-conscious Gov. Charlie Crist, the school fitness law is aimed at tackling childhood obesity and promoting active lifestyles among Florida's youth.

Donna Powell, whose kids attend Jupiter Elementary, said she doesn't mind that there's no more recess. "As long as they're doing some physical activity, what difference does it make?" she said.

But Jupiter Elementary student Stacey Francois, 13, complained: "We don't get to sit down and relax and just have our fun and talk. Now, we have to keep on moving and walking."

Lynn Hartle, an associate professor of early childhood education at the University of Central Florida, said the new law not only puts a burden on classroom teachers who haven't been trained to provide physical education, but it also cheats students.

"It's just a shame to take away any time where kids get to make decisions both socially and cognitively about what they want their bodies and minds to do," she said.

Also, recess advocates and researchers who have studied the effects of unstructured free time on kids say less time in the classroom and more time playing might actually improve children's academic performance.

"The research is pretty clear that when kids do get recess they can come back to learning with increased focus and actually perform better," said Eva Zygmunt, a Ball State University professor. "When they sit for long periods of time, they lose attention."

Some Florida schools have found ways to fit the extra P.E. time into their schedules and still offer some recess.

At Indialantic Elementary, students have recess every day except Fridays, when they have to walk or run laps around the school campus. In addition to two 40-minute P.E. classes each week, students also participate in 10 minutes of P.E. in the classroom each day after morning announcements.

P.E. teacher Paula Goodman said she doesn't expect immediate fitness or health improvements among her students.

"I think the problem with nutrition and obesity will take a long time for families and children to get back on track," she said. "Parents have to change, too."

Andy Gammill of The Indianapolis Star contributed to this report.