A U.S. study suggests a link between the amount of time girls spend in physical education class and their academic achievement.

The researchers said physical education may boost academic achievement by increasing blood flow to the brain and fostering positive classroom behaviors.

Susan Carlson, an epidemiologist with the U.S. Centers for Disease Control and Prevention, said data from a longitudinal study of students in kindergarten through fifth grade showed that girls who were enrolled in 70 minutes or more of physical education each week scored significantly higher on tests for math and reading than girls who had fewer than 35 minutes of physical education each week.

The report, published in the Journal of American Public Health, said higher amounts of physical education did not appear to have a negative or positive impact on academic achievement among boys. USA Today said

Carlson suggested that a higher level of physical activity might be needed to yield the same result for boys.

Copyright 2008 by United Press International