NEW YORK -- A newly released study finds that kids who are in shape do better on academic tests.

During the 2007-2008 school year, students in New York City public schools who scored in the top 5 percent on their NYC Fitnessgram assessments outscored the bottom 5 percent of students on standardized academic tests by an average of 36 percentile points, the study finds.

The study was released by New York City’s Health Department and Department of Education as part an analysis of data from the Fitnessgram tests. Each year, the city’s school students undergo a comprehensive fitness assessment using the Fitnessgram testing as part of their physical education program.

The analysis also finds that childhood obesity remains a problem in New York City. Researchers said 21 percent of kindergarten through eighth-grade students are obese, and an additional 18 percent of the city’s students are considered overweight.

“The long-term health of our students is very important,” Joel I. Klein, schools chancellor, said in a statement. “The report’s findings send a clear message to schools, parents and health care providers to do everything possible to ensure that children receive the opportunities for physical activity and the proper nutrition that will help them stay fit and healthy.”