Parents should ask local councils to regularly shut down their streets so children can play outside, British cyclist Jason Kenny has said.
The six-time Olympic gold medallist told the BBC that traffic on residential roads was one of the "big hurdles" for parents who wanted their children to play outdoors near home.
Kenny's call is part of the Playing Out campaign, which began in Bristol.
Playing Out says only 21% of children play on their street regularly.
"A lot of parents don't feel confident to let their kids out on the street in front of them," Kenny said on Radio 5 Live.
"So it's giving them power to get in contact with the council, make it official and shut the road for a bit and let the kids play out."
Barney Worfolk-Smith, who lives in Hackney, London, is among a growing number of people trying to persuade their council to regularly shut their streets to help children play outside.
He says there is now a "thriving" community based around the efforts, which he has been organising for the past three years, with about 15 children and 20 adults regularly taking part.
Mr Worfolk-Smith says his son did play outside "a bit" prior to the closure - but, he adds, it has "without doubt changed the colour, the attitude, of everyone around".
"I really believe in this," he tells BBC News. "I grew up in the countryside, I had complete freedom, especially on my bicycle.
"We try to do it every single month.
"On Sundays from two until four we shut off the streets - the main reason is for children to come out and reclaim the streets, but I'm also a big believer in community, in getting the neighbours out and talking to the older people who live here."
Not only does closing the road encourage children to play out at the time, Mr Worfolk-Smith says, but it has also "normalised" playing outside on a regular basis.
"There's a gang of kids out most nights now just on their roller skates or bikes just having fun," he says.
Holly Beasley says her street in Stockport used to be "civil but quite distant", with almost none of the children playing outside before the road closures were organised.
"But now lots of children do play out and there's a good mix of ages," she says. "Lots of the children go to different schools but actually they've become friends and built those new friendships and little networks locally."
The road closures have been taking place on Ms Beasley's street for almost two years, and while she admits not all residents were keen on the idea initially, that has changed.
"People have come round to the idea and have realised it hasn't had any negative impact on their lives and has only brought good things for them," she says.
"I think the biggest surprising benefit has been the adult friendships.
"Not just for those of us who are directly involved in organising it - there are a lot of older people on the street who have really embraced it.
"I was surprised to see people who don't have children coming out regularly and just enjoying having a cup of tea and just getting involved in the practical side of things."
'Dangers of the road'
However, not everyone is convinced by the campaign.
Dan Plummer, a resident of Bristol, questioned whether the idea could lead children to be less careful on roads in general.
"We should be very careful about normalising playful activities on roads," he told the BBC.
"Closing roads and allowing children to play on these roads may cause children to not think of the dangers of the road in other environments.
"Rather than allowing children to play on the road, perhaps parents could take their children to parks."
Phil Crampton, from York, echoed that sentiment, saying he didn't believe the idea would catch on.
"Why can't the parents take their kids to the local park like they used to do?"