Most Canadian kids are earning a failing grade on a new report card assessing their levels of daily exercise.

Active Healthy Kids Canada's annual report card on physical activity for kids found that 87 per cent of children and youth are not getting in the recommended minimum of 90 minutes of physical activity a day.

Despite the dismal numbers, that's still an improvement compared to 2006 when 91 per cent of kids weren't reaching the target.

The report card also found that 90 per cent of Canadian children are spending too much time in front of television, computer and video game screens. Most recommendations urge limiting screen time to no more than two hours a day.

Mark Tremblay of Active Healthy Kids Canada notes that part of the problem is that schools and parents are choosing to have kids studying more than playing.

In our eagerness to ensure academic success, schools are cutting out time during the school day for exercise and devoting it to sedentary study. Yet research suggests that reducing physical activity doesn't improve test scores, Tremblay says; instead, exercise appears to help kids learn better.

There may be biological reasons for this, Tremblay explained to Canada AM Tuesday, noting that exercise may increase blood flow to the brain or alter hormones to help with memory. Or, it might be that exercise provides psychological benefits, by improving self-esteem.

Or, it could be that exercise offers emotional effects.

"We've probably all experienced this: when you go out for a walk at lunchtime and you come back to the office and you feel more sedate, better able to get back to work and more creative," he said.

"We seem to have this misguided belief that spending more time in the academic subjects will improve things. But we can't suppress the natural energy of kids. We need to help them exert that energy. And the evidence suggests that will improve their academic performance."

On the group's annual report card, School Physical Education and School Policy rated a mediocre "C-" and "C" respectively, across the country.

Parents, too, take some of the blame for their kids' low activity levels. Tremblay says he hears from parents that they are busy and simply don't have time to make sure their kids get out and exercise. But that doesn't bear out with the research that's been done, he says.

"When we ask parents how much time they spend recreationally in front of the screen, it averages two to three hours per day. Well, that's more than enough time to get to the park and play with the kids or get in the driveway or backyard to play catch," Tremblay says.

"It's certainly an issue of social norms. We've established this behaviour of cocooning inside houses, in front of screens, child in front of that screen, parent in front of this screen. You're comfortable, you're safe, you're near the pantry, but those are all parts of the problem."

The report card gave Canadian kids a "D" for Active Transportation, meaning most are not choosing to bike or walk to get to school.

Parents should encourage their children to walk or bike to school each day, since nearly two-thirds of Canadian families live within a reasonable distance to walk or bike to school, Active Healthy Kids Canada urges.

If parents' schedules don't allow them to supervise the route twice a day, parents should team up with neighbours to form a "walking school bus," the report suggests.

Municipal governments can help too by investing money in parks and sport, while also reconsidering policies and by-laws that act as barriers to play in their communities.