(NewsNation) — More sedentary time as a child could lead to a higher chance of heart attacks and strokes later in life, researchers found in a new study.

Even for those at a normal weight and blood pressure, hours of inactivity from childhood to young adulthood was associated with heart damage. This study was conducted as part of the Children of the ’90s study by the University of Bristol, in which over 14,000 children born between 1991 and 1992 and their families were “intensively observed” for over two decades.

“All those hours of screen time in young people add up to a heavier heart, which we know from studies in adults raises the likelihood of heart attack and stroke,” the study’s author, Dr. Andrew Agbaje of the University of Eastern Finland in Kuopio, said. “Children and teenagers need to move more to protect their long-term health.”

As part of the research, 11-year-old children were given a smartwatch with an activity tracker to wear for seven days. They were then given the smartwatch at 15 years of age and again at 24.

Scientists measured these children’s hearts with a kind of ultrasound scan called an “echocardiography” when they were 17 and 24, after they adjusted for outside factors such as age, sex, blood pressure, body fat, smoking, physical activity and socioeconomic status.

The 766 children studied were sedentary for an average of 362 minutes a day. That number grew to 474 minutes once they hit adolescence, and 531 when they were 24, making for a 169-minute increase between those years.

Each one-minute increase in a child’s sedentary time from ages 11 to 24 was associated with a 0.004 g/m2.7 increase in their heart’s left ventricular mass when they were 17 to 24.

When multiplied by 169 minutes, that additional inactivity totaled a 0.7 g/m2.7 daily rise, which researchers said is equal to a 3-gram increase in left ventricular mass between each heart measurement for those who grew taller at an average rate.

Previous studies in adults showed a similar increase in left ventricular mass of 1 g/m2.7 over a seven-year period was associated with a two-fold increased risk of heart disease and stroke.

“Our study indicates that the accumulation of inactive time is related to heart damage regardless of body weight and blood pressure,” Agbaje said. “Parents should encourage children and teenagers to move more by taking them out for a walk and limiting time spent on social media and video games.”

According to HealthDay, this research is set to be presented at the European Society of Cardiology‘s meeting set for Aug. 25 to 28. Until published in a peer-reviewed journal, these findings are considered preliminary, HealthDay wrote.