One of the reasons the Dutch authors decided to conduct their research review was concern over schools' emphasis on test scores.
"There is a focus on test scores and academic accomplishments, and there's a belief that schools need to cram all available time into academics," said Dr. David Geier, director of sports medicine at the Medical University of South Carolina in Charleston.
Geier was not involved in the Dutch research.
"The other problem," Geier said, "is that it becomes a funding issue for many schools."
If intellectual activities are incorporated with physical activities, Geier said, children will benefit both ways.
Geier's colleagues at the Medical University of South Carolina and a group of educators recently tried that combination at an elementary school. They incorporated 40 minutes of physical education every day that included a learning component for different grade levels. As an example, young children rode scooters while tracing shapes at the same time.
When the students took their spring standardized tests, more children achieved their score goal after the new physical education program than before it was implemented.
But even if there are no academic gains, physical activity in schools is still very important.
"There are cardiovascular benefits as well as decreased obesity and a decline in juvenile diabetes," said Geier.
"There's an even greater need for physical education now, because the vast majority of children's leisure activities are sedentary and involve technology," said Keith Ayoob, associate professor of pediatrics at the Albert Einstein College of Medicine in the Bronx, N.Y. "The problem is our bodies were not designed with technology in mind. They were designed for physical activity, and both children and adults should use this ability or we risk losing it."
While they reported an overall positive association between activity and academics, the Dutch authors stressed their conclusion was "cautious" because very few studies they analyzed were scientifically strong.
"Only 2 of 14 studies were rated as being of high methodological quality, which is the minimum number of studies needed for 'strong evidence,'" they wrote.
The studies also measured physical activity and academic achievement differently, and physical activity information often relied on self-reporting, which can be unreliable.
Because of the limitations of the prior research, the authors said more "high-quality" research is needed to accurately measure the relationship between physical activity and school performance.
"To gain insight into the dose-response relationship between physical activity and academic performance, we need more high-quality studies using objective measures of physical activity," they wrote.