Children spend less than 4 percent of the time they are awake in physical activities, which is just about 20 minutes a day, says a new study. The recommended time for physical activity is about 60 minutes for children.

Switching off that TV will not increase physical activity either. The study found that parents who restrict TV use have children who play less than other kids.

The study involved some 500 children aged between 8 and 10 years. They wore activity monitors that tracked all their physical activities. Researchers were surprised to find that children as young as 8 were not playing as much as they should be at this time of age.

"Given the importance of physical activity in maintaining good health, we know we need to get our kids more active. What we hadn't known until now is how young we need to be catching them, or the reasons that lay behind their lack of activity," said lead author Dr. Mark Pearce from Newcastle University.

Girls tend to spend even lesser amounts of time on play, especially if they are more than 8 years of age.

"Already at the age of eight, we are seeing girls being less active than boys. This is something which we know then gets worse as they approach their teenage years," said Pearce.

"One of the important things is that most girls don't see sport as cool. We need to be tackling these issues earlier by encouraging girls to exercise, by providing a wider range of opportunities than are currently on offer and by ensuring they see positive female role models, particularly in the media," Pearce said.

According to the study, children of older fathers are less physically active. A reason may be that older fathers are at senior work positions and spend longer times at work.

"We think there may be a variety of explanations for this such as older fathers reaching more senior posts and having to work longer hours or maybe seeing themselves in a more traditional role so spend less time in active play with their children," Pearce said. 

Playing video games that increase physical activity is helpful in making children more active, says a study from 2009.

Researchers say that energy expenditure during an active game is comparable to moderate-intensity walking.

"There is an urgent need for interventions, at home and at school, which will help primary school children become more physically active." said Professor John Reilly from the University of Strathclyde, one of the study authors.

According to the Centers of Disease Control and Prevention, 12.5 million children and teens are affected by obesity which is nearly 17 percent of all children in U.S. According to the agency, children now are getting heavier than ever. In the past few years childhood obesity has almost has tripled. A sedentary lifestyle is blamed for this increase in obesity rates. According to many reports, children spend less time on physical activities now than in the past.

The study is published in the journal PLoS ONE.