Children must exercise more, study says

For a new study were selected over 1,700 children, aged 9 or 15 years, from schools in Denmark, Estonia, and Portugal. In addition to measuring each child's amount of daily activity, the researchers also measured risk factors for cardiovascular disease, such as blood pressure, weight, waist circumference, insulin resistance (a precursor for diabetes), and blood cholesterol, according to Forbes.

While previous studies into childhood activity simply asked kids how much exercise they got per day, Andersen's team equipped children with accelerometers - devices that measure everyday activities such as moderate-intensity play and walking to school, Health Day News reports.

Researches found that the more the children exercised, the more their combined risks factor score decreased, according to Scotsman.

Nine-year-olds who did 116 minutes of moderate to vigorous exercise a day and the teens who exercised for 88 minutes daily had the lowest risk factor scores, according to the research published in The Lancet medical journal.