Children need to move more according to the research
Half of all seven-year-olds are not getting enough exercise, especially girls who are far less active than boy, according to new research.
The figures show that they are sitting for up to seven hours a day, which is almost half the time that they are awake.
Only one in two is active for the recommended minimum of 60 minutes a day. For girls, the figure was just 38% compared with 63% for boys.
Prof Carol Dezateux, one of the lead authors, told the BBC: "There is a big yawning gap between girls and boys. We need to really think about how we are reaching out to girls.
"The school playground is an important starting point. Often you will find it dominated by boys playing football."
The new research, published in the online journal BMJ Open, by experts from University College London's Institute of Child Health examined data for 6,497 children.
The youngsters wore an accelerometer to measure exercise levels which was attached to an elastic belt round their waist. It was only removed when bathing or when the children went to bed.
The research shows that fitness levels of British children are falling faster than anywhere else in the world as obesity levels are rising.
But the time spent by children in sedentary behaviour reveals their health could be at risk simply because they are sitting too much.
Prof Carol Dezateux continued: "The findings are particularly worrying because seven-year-olds are likely to become less active as they get older, not more."
Tagged in exercise Obesity children's health fitness tips