The Fitter Schools UK Challenge set up by Fitness Sport, a children's sports organisation, encourages schools to give pupils two hours of high quality PE a week.
Those schools which demonstrate the greatest improvement in pupil fitness within 14 weeks will win sports equipment and coaching services for their pupils.
Participating schools will be sent a teachers' pack including lesson plans and activity suggestions. They are also advised to encourage extra-curricular fitness activities such as walking to school or running the last 100m to the gates.
Last year, 3,000 schools took part, improving their pupils' fitness by 14.5 per cent. This year's challenge will be launched on January 14 by Ian Wright, the former England footballer.