A Minnesota school is experimenting with letting pupils roam free during lessons to see if they can kick the sedentary habits behind rising obesity.

Twenty-six nine to 10-year-olds at Elton Hills Elementary School in Rochester, Minnesota, have traded their desks for adjustable “learning stations,” at which they can stand, sit or kneel. They have also been given large exercise balls to sit on, and the freedom to move around as they wish in class.

Jerry Williams, superintendent of Rochester’s schools, said: “It’s a way of embedding physical activity into school, as opposed to limiting it to break-time or PE.”

The trial, which began in March and will run until the end of the school year, is the brainchild of Dr James Levine, a British scientist at Minnesota research institute, the Mayo Clinic. If succesful it will be extended to other local schools.

School anti-obesity efforts typically focus on intense bouts of physical activity in games lessons and encouraging pupils to eat less junk food. But the Minnesota experiment is designed to see if encouraging greater habitual movement - a growing area of interest among researchers - is more effective. Dr Levine said science is starting to view obesity as state of sedentariness. “It’s associated more with inactivity than previously thought.”

He had feared the experiment could prove a recipe for chaos with children “bouncing off walls”. But he was surprised to find that the freedom to move made students calmer. “There may be even more to this than addressing childhood obesity,” Dr Levine said.