Youngsters are putting themselves at risk of heart disease in later life by not exercising, medics have warned.
A new initiative has been launched for schools to get young teenagers to improve their health and fitness, as well as mental health and academic performance.
Exercise physiologist Dr Sarah Kelly revealed a quarter of schoolchildren have risk factors for heart disease like poor aerobic fitness levels, being overweight or obese and having high blood pressure.
Some 86% spend more than two hours a day watching TV or playing on the computer, with almost nine out of 10 Irish children insufficiently active to benefit their current or future health, she warned.
"Only 12% of 10 to 18-year-olds in Ireland are meeting the Department of Health and Children physical activity recommendations of at least 60 minutes of moderate to vigorous physical activity daily," said Dr Kelly.
"Girls are less likely than boys to meet the physical activity guidelines, and the amount of time being dedicated to physical activity every week, typically one hour, is totally inadequate."
Dr Kelly and Professor Niall Moyna, from the Centre for Preventive Medicine in DCU, have joined forces with Aviva Health Insurance to launch the schools fitness challenge, which aims to get first and second year pupils nationwide improving their health and fitness.
Schools should visit www.avivahealth.ie/fitnesschallenge by Friday January 18 and receive a registration pack with the fitness test audio on CD, and step-by-step guidelines.
"I wouldn't be where I am today unless I had exercised as a child," he said at the launch. "For me, being active when I was younger contributed enormously to my ability to play Gaelic football at intercounty level today. I am incredibly grateful to the coaches and teachers who placed an emphasis on physical fitness."