DENVER (CBS4) – Boot camps, yoga, jogging groups — people love working out in Denver’s city parks, but now workout groups might have to pay to break a sweat in a park.

Next week Denver City Council will discuss fees for fitness classes who use city parks.

At 6 p.m. on Friday happy hour at City Park means an intensive boot camp lead by Chris Lindley.

“These are adults having a wonderful time in the most beautiful park in the city,” Lindley said.

They could be athletic warriors or mothers with strollers, but exercise classes in city parks are all the rage. Now city officials say commercial activity in parks should require a permit and fees. Parks and Recreation officials say the ordinance has always been on the books.

“A lot of these groups really are businesses that provide their goods and services in the park,” Jeff Green with Denver Parks and Recreation said. “If they don’t have a permit, they’re kind of breaking the law.”

Now city council is considering adopting a permit and fee structure. Under it the cost for one 90-minute session would range from $4.50 to $32.50 depending on the park, season and time of day for groups of 25 people or less.

“We live in Colorado. This is beautiful. Why shouldn’t we be out here?” said Tonia Seidl, who was in Lindley workout group.

“We should never discourage exercise, we need to encourage exercise (and) remove every barrier possible,” Lindley said.

Parks and Recreation says they want to encourage exercise but at a reasonable expense.

“We want people to enjoy our parks and this is kind of balancing the needs and wants of the commercial operators with the way that regular citizens and general park visitors use the park,” Green said.

A city council subcommittee will meet Tuesday morning to hear public comment and to vote on whether to advance the issue to the full council.