Gold medal-winning runners Paula Radcliffe and Kelly Holmes have joined thousands in criticising a parish council's decision to charge for a weekly fun run.
More than 300 people take part in the timed 5k parkrun at Little Stoke Park in Stoke Gifford, south Gloucestershire, each Saturday at 9am.
Stoke Gifford Parish Council has recently paid £55,000 to resurface the car park, while the path will soon need to be replaced at a cost of £60,000.
It says the fun run, which has been taking place each week for three years, has led to "increased wear" and complaints from local residents.
But more than 18,000 people have signed a Change.org petition against the council's decision to charge parkrun to use the grounds.
Parkrun has more than 850 weekly events in 12 countries, all delivered by volunteers and free to take part.
Paula Radcliffe tweeted: "Am totally against this short sighted decision. I fully support the right for this event for children to be free."
She later clarified that the event, which is open to adults, children and dogs at most locations, should be "free for everyone, always".
Dame Kelly Holmes also took to Twitter to criticise the council, writing: "Have I missed the whole reason park runs exist & are free? StokeGiffordParishCouncil decision is a disgrace .com."
Ben Fogle tweeted: "Stoke Gifford Parish Council should hang their heads in shame. We should be encouraging community health not charging for it #parkrun."
In a statement issued after the council voted to charge for the event, parkrun said it was "extremely disappointed" at the decision.
Chief operating officer Tom Williams said: "Parkrun has had unprecedented success in engaging the least active and encouraging them to exercise regularly.
"Providing free weekly access has been fundamental to this and we are disappointed that this opportunity is to be removed for the residents of Little Stoke.
"Our aim is to break down barriers to participation in, and delivery of, physical activity and this is consistent across 850 parkruns worldwide, which are all delivered by volunteers and are free to take part in.
"Imposing a charge at one event is something that contradicts our founding principles and would set a precedent that threatens our future.
"As a nation we must make a decision about whether we want to be healthier or not. The costs to all of us of inactivity and poor health are immense. Parkrun has had enormous success at bringing communities together and promoting physical activity in safe and welcoming social environments.
"The past six months have been an uncertain and difficult time for everyone involved with Little Stoke parkrun and our entire global community of more than two million parkrunners is behind them as we discuss our next steps."
The council said the park had requested that parkrun contribute "a small monetary amount" towards the upkeep, which had been refused.
It described parkrun as an organised group with paid directors and staff and no limitations on the number of runners who can attend.
Runners - including a "large number" from outside the parish - use park toilets and washing facilities, the council said.
Complaints involving incidents with runners have been received from local residents relating to parking, as well as from other park users and hall hirers.
"Parkrun are an organised group and like any other group using the facilities should contribute towards the maintenance," the council said.
"The parish council has only recently paid out £55,000 from public funds for resurfacing the car park and with the additional 300-plus runners per week, will shortly need to replace/repair the path at an estimated cost of £60,000, so as parkrun are significant users of the path on a regular basis they should contribute towards the upkeep."
The council said the precept had been kept to a minimum over several years, with the authority having among the lowest tax rises across south Gloucestershire.
But it is likely this will increase if the council continues to support free-of-charge groups, resulting in residents funding maintenance and repairs caused by runners, it added.
"Parkrun maintain it is their ethos to remain 'free of charge' and have repeatedly stated they will not pay towards the upkeep even when the council offered to complete a grant application on their behalf and all that was required was their signature," the council said.
"The parish council cannot and will not stop people from using the parks for exercise and running but when it comes to an organisation with paid directors, fundraisers and sponsors, it would be unfair to expect the residents to pay."
Little Stoke Parkrun said the charge meant the parish council was "withdrawing permission for parkrun to use the park".
"It is a fundamental principle of parkrun that there should be no barriers to participation and events should always be free," it said.
"All we were asking the council for was shared use of the park for a short period early on Saturday and Sunday mornings.
"The council's decision will inevitably increase numbers at other parkruns in the area and we will work to secure an alternative venue and establish new parkrun events to cater for the growing number of people who are opting to get fit by running regularly."
The event said it had received hundreds of messages following the decision, including many moving stories of how parkrun "is changing lives".