Some morning exercise before beginning school can calm symptoms in kids with ADHD, researchers suggest, and offer an alternative to drug treatments.

In a study, young children displaying signs of attention deficit hyperactivity disorder were increasingly attentive and showed less moody behavior after participating in regular, half-hour aerobic activity sessions before school, the researchers report.

ADHD is believed to be caused by deficiencies found in the frontal cortex of the brain, responsible for governing attention, impulse control, planning and reasoning.

Prior studies have demonstrated this area can be strengthened with consistent and frequent physical exercise, the researchers from Michigan State University and the University of Vermont say.

Even a single session of exercise has been shown to improve the attention and academic skills of students, they say.

"This gives schools one more good reason to incorporate physical activity into the school day," says Alan Smith, head of the MSU kinesiology department.

In the study, 200 children from kindergarten through second grade were assigned randomly to two groups, one that performed brisk physical activity before school for 12 weeks and another that kept their before-school routines as usual with more sedentary activities.

The children included some showing typical development and others classified as possible having ADHD based on teacher and parent assessments.

"Although our findings indicated that all participants showed improvements, children with ADHD risk receiving exercise benefited across a broader range of outcomes than those receiving the sedentary activities," Smith says.

Some teachers say they've seen evidence of that in their own classrooms, finding that allowing their student to engage in short periods of physical activity improved their ability to devote attention to classroom studies.

"It benefits all the kids, but I definitely see where it helps the kids with ADHD a lot," says Jill Fritz, a fourth-grade teacher at Rutledge Pearson Elementary School in Jacksonville, Fla. "It really helps them get back on track and get focused."

With many schools cutting back on recess periods and physical education amid increasing curriculum demands, programs involving students in exercise either before or after school or during short breaks in the classroom could offer the same benefits, the researchers say.

More study may be needed to understand exactly how much exercise and how often might best provide benefits to children, they say.

"Despite the number of remaining questions, physical activity appears to be a promising intervention method for ADHD with well-known benefits to health overall," Smith says.