A new Swiss study has found that stretching the PE lessons at school and assigning kids a ten minute exercise homework can improve their fitness.
The study has appeared online in the British Medical Journal.
The research showed that children who exercised more at school and during homework were fitter and put on less weight than others.
The research, which lasted a year, compared the health of children given extra exercise with their counterparts on the standard three lessons a week programme.
It was seen that children aged seven and 11 who did the extra exercise could run the equivalent of 20 seconds faster, their body fat as measured by skinfold thickness was 2mm less and their body mass index improved.
However, there was no major shift in overall daily physical activity and quality of life.
"To our knowledge, this is the first study of a school based, long term physical activity intervention that documents beneficial changes in all these parameters," the Telegraph quoted lead author Susi Kriemler, assistant professor for paediatric sports medicine in the Institute of Exercise and Health Sciences, University of Basel, in Switzerland, as writing.
Kriemler added: "Our study was a demanding "real life" intervention trial, in which we successfully increased physical activity, thereby achieving multiple beneficial health effects."