Kids younger than two shouldn't spend any time in front of a screen - be it a TV, a computer or a tablet, the guidelines say. And for children aged two to four, screen time should be limited to less than an hour a day.

"There's no redeeming feature of screen time under the age of two," says Mark Tremblay, who chaired the committee that drew up the guidelines and is lead author of two scientific papers which analyzed of about 40 published studies to come up with the two sets of guidelines.

"Don't use screens as hypnotic elements to entertain them, to just pass time. It's not advantageous for the healthy growth and development of a child to do that."

Tremblay is also director of the Healthy Active Living Obesity research group at the Children's Hospital for Eastern Ontario Research Institute in Ottawa. The guidelines were crafted by the Canadian Society for Exercise Physiology and ParticipAction, with help from Tremblay's group.

The guidelines suggest children under one should be allowed to partake in active play several times daily - including things like tummy time, reaching and grasping and crawling.

For kids aged one to four, parents should aim for three hours of activity a day. The activity can be any kind, Tremblay says, and doesn't have to be rigorous. Walking, crawling, playing - anything but sitting. By age five, children should be spending at least an hour a day in energetic play - activities like hopping, skipping and bike riding.

These bars may seem low. Many people have the notion that little kids are always on the go. But in fact, that isn't the case, says Kelly Murumets, president and CEO of ParticipAction.

When allowed to play outside, children do become very active, Murumets says. But when they are indoors, particularly if there is a TV or computer screen around, that's another matter.

"I don't know what it is, I'm sure there's some physiological explanation for this, but they become transfixed by the screen. And they will sit and be sedentary for much longer than you would expect toddlers's DNA would allow," she says.

The professional organization representing Canadian pediatricians is adding its support for the guidelines. The Canadian Pediatric Society is issuing its own guidance, which mirrors the recommendations on the amount of activity children should get daily.

The society's guidelines also call on doctors to counsel families on the importance of encouraging children to be active and advise them on how to achieve that end.

Over the last quarter century, the obesity rate has nearly tripled among children and youth, the pediatrics society notes in its statement. As many as 26 per cent of kids between two and 17 years are now overweight or obese, and that number jumps to 41 per cent among First Nations children.

"We're starting to see kids with health and obesity problems before they even start school," says Dr. Claire LeBlanc, chair of the society's committee on healthy active living and sports medicine.

"Parent and caregivers need to incorporate age-appropriate physical activity into their children's day as young as possible."

Tremblay says studies that monitor and evaluate what young children do find they are actually far more sedentary than most people would think.

"We measure them. Many people have measured them. It's very clear - they're not active most of the time. The vast majority of the time, in fact, they're almost completely idle. And so we need to change that balance a little bit," he says.

That said, on average, many kids may be close to hitting the mark when it comes to the activity targets.

"The direct measured literature actually shows that most kids in developed countries actually achieve more than two hours (a day)," Tremblay says.

"The minority, very few, actually achieve three hours. Given the drift that we're seeing in obesity and some health problems, it's reasonable to assume that perhaps we're not where we want to be. But this is a reasonable target to get to."

Where more progress needs to be made, though, is on the sedentary behaviour side. The guidance suggest children shouldn't sit for more than an hour at a time, whether that's in a stroller, high chair, or, ideally, even in a car seat.

Tremblay says the committee that drew up the recommendations suggests that long car rides should be broken up so that kids can be allowed to get out and move about once an hour.

Tremblay says frequent activity contributes to bone, motor skill and cognitive development and protects against the harms associated with excessive sedentary behaviour.

Copyright The Canadian Press