As kids spend too much time glued to their couches while watching TV or playing video games, a new study warns letting children sit for long hours could lead to long-term health risks.

CNN reports a research published in the journal Experimental Physiology says long periods of inactivity for children increases risks for cardiovascular problems that potentially cause heart attack and stroke when they become adults.

For the study, researchers checked the blood circulation of nine girls, ages 7 to 10, after spending three hours sitting on beanbag chairs watching movies and playing games on iPads. Few days later, the children came back for a similar experiment except that they were asked to stand up for a 10-minute exercise every hour.

Researchers found out that the couch potato sessions decreased the flexibility of the thigh artery by 33% and there was no difference even when they stood up for exercise. The thigh artery, however, could just eventually return to its normal flexibility in due time.

According to Alison McManus, associate professor of pediatric physiology at the University of British Columbia and lead author of the study, the stiffening of the thigh artery may increase risks forcardivascular diseases by 25%.

"We didn't expect quite such a profound effect in children," said McManus, adding the children only spent eight minutes moving their legs or standing. "We always have this idea that kids fidget (but) they are very good at sitting still."

Alan Hedge, an ergonomics professor at Cornel University who was not involved with the study, says sitting for long hours also has similar effects to adults. "This research suggests that children are not that different from adults in terms of fundamental physiology of the body," Hedge said. "It confirms that sitting compresses blood vessels in young people just as much as it does in adults [and] just as much as it does in elderly."

Hedge advises standing or moving for at least 10 minutes every half an hour could help reduce risks.