Increasing the amount of physical education at school would make a "big impact" towards getting Kiwi kids off the couch, according to researchers at the University of Otago.
Data collected from 9000 kids aged 5-17 shows 39 percent don't meet physical activity guidelines and 19 percent don't even do half the recommended amount.
Researchers found that if New Zealand followed international best practice and introduced a mandatory time requirement of 2.5 hours of PE at school per week, the percentage of kids who are only "minimally active" would half.
Researcher Dr Anja Mizdrak told the AM Show several other countries already have a mandatory time requirement for PE.
"Quite a few countries have a mandatory time requirement for PE so we looked at what would happen if we implemented this here."
She says having a mandatory time requirement would mean more Kiwi kids would meet the World Health Organization's recommendation of "an hour a day of movement."
"The mandatory component," she adds, "is about having some sort of time requirement and guidance for schools because what we're seeing is some schools are doing a really great job and kids are doing loads of activity and others aren't doing so well ."
Dr Mizdrak says researchers want to make sure "across the board" that kids are having the opportunity to be physically active at school.
She says PE at schools needs to be a "quality activity" that kids can actually enjoy so they are encouraged to participate further.
"I think it's really important that kids have a positive experience of physical activity, otherwise we risk kids hating it and then going on to be physically inactive adults."
"They then want to go and be active and not sit around looking at TikTok."
The increasing amount of time kids spend on screens at home is what led researchers to focus on school as a place where they can encourage a large number of kids to get active.
"I think we are seeing that kids are spending a lot of time on screens but really our research was on looking at schools as a place where kids can be physically active, and really it's a place where we can reach a large proportion of kids."
While walking to and from school and activities within school all contributes to the recommended hour she says it's also "important to do more vigorous activity."
"Of course different types of activity are also important in terms of doing things that are going to help strengthen muscles."
The Ministry of Health recommends kids have no more than two hours of recreational screen time per day and participate in vigorous physical activities that strengthen muscles and bones, at least three days a week - alongside the one hour of moderate activity.