Researchers from the Cochrane Library say school-based health and exercise programmes offer positive outcomes despite having little effect on children's weight or the amount of exercise they do outside of school.
The researchers carried out a systematic review of studies on physical activity programmes in schools in Australia, South America, Europe and North America and found that school-based programmes increased the time children spent exercising and reduced the time spent watching television - such programmes also reduced blood cholesterol levels and improved fitness even though they had little impact on weight, blood pressure or leisure time activities.
Experts believe a lack of physical inactivity is a contributing key factor behind 1.9 million deaths every year and almost a quarter of all cases of coronary heart disease.
It has been shown that people who are overweight as children are more likely to develop heart disease as adults and exercise helps to maintain a healthy weight, but most children do not do enough exercise to gain any health benefit.
The World Health Organisation (WHO) says schools are important settings for the promotion of physical activity among children.
From the 26 studies of physical activity promotion programmes in schools reviewed, it was found that most tried to encourage children to exercise by explaining the health benefits and changing the school curriculum to include more physical activity for children during school hours.
These programmes included teacher training, educational materials and providing access to fitness equipment and lead researcher, and Maureen Dobbins, from McMaster University in Ontario, Canada, says that schools should continue their health promotion programmes.
