The importance of allowing children to play outdoors has been highlighted in a new study.

Currently, children and teenagers are recommended to participate in a minimum of 60 minutes of moderate to vigorous activity (MVPA) every day. Previous studies have shown that young people get most of their MVPA while they are in school.

Canadian researchers therefore set out to confirm that increasing the time spent outdoors after school would increase MVPA levels among young people.

They monitored 306 young people aged between nine and 17 during the academic year 2008/2009. Participants completed online surveys about their activities and also wore accelerometers - a device used to measure the acceleration of a moving body.

The study found that young people who did not spend time outside after school undertook 21 fewer minutes of MVPA per day and were sedentary for an additional 70 minutes per day, compared to those who spent most of their time outside after school.

Overall, those who spent time outside after school were three times more likely to achieve their daily recommended levels of activity than those who did not. They also had better overall fitness.

The results applied to the winter months as well.

The researchers called for more promotion of outdoor activities among young people in order to boost activity levels and improve fitness.

Details of these findings are published in The Journal of Pediatrics.