A new research reveals that school students who stayed in the best physical shape also performed better than their classmates and took home better report cards.
The first ever study by the Michigan State University linked children's fitness to both improved scores on objective tests and better grades, which rely on subjective decisions by teachers.
The study also is among the first to examine how academic performance bears on all aspects of physical fitness - including body fat, muscular strength, flexibility and endurance - according to Dawn Coe, who led the research at Michigan, the Journal of Sports Medicine and Physical Fitness reported.
"We looked at the full range of what's called health-related fitness," said Coe, who conducted the research as a doctoral student in Michigan kinesiology department and is now an assistant professor at the University of Tennessee, Knoxville.
"Kids aren't really fit if they're doing well in just one of those categories."
Coe and colleagues gathered their data from 312 students in sixth through eighth grade at a school. They gauged the kids' fitness with an established programme of push-ups, shuttle runs and other exercises.
Then they compared those scores to students' grades throughout the school year in four core classes and their performance on a standardized test.
The results showed the fittest children got the highest test scores and the best grades, regardless of gender, according to a Michigan statement.
"Look, your fitter kids are the ones who will do better on tests, so that would argue against cutting physical activity from the school day," said study co-author James Pivarnik, Michigan professor of kinesiology and Coe's guide on the project.