Don't let the beaming smiles, the friendly banter and the gentle camaraderie of its contestants fool you. Pickleball is not for the fainthearted.

"Frank has left some of his DNA on the court," Denny Johnson said of the many skinned knees and bruises earned by his 82-year-old friend and pickleball partner Frank Slater.

Said Slater: "You've gotta be tough."

The dramatic growth of the game — which looks like tennis but is played on a badminton-sized court with what look like giant Ping-Pong paddles — prompted Forest Lake recently to open a new set of pickleball courts at its Fenway Park athletics complex. Since unofficially opening two weeks ago, not a day has gone by when dozens of people weren't knocking the ball back and forth, said Jamie Muscha, the city's Park and Recreation coordinator.

"The game is for everybody. Schools are starting to teach it," Muscha said. "But it's very popular among the senior population. And we are really striving to have something for everybody."

According to the USA Pickleball Association, the game was invented in 1965 on Bainbridge Island, Wash., "by three dads whose kids were bored with their usual summertime activities." It has since gained players in Europe and Asia, and according to the Sports & Fitness Industry Association, almost 2.5 million people play pickleball in the United States.

Over the past few years, the surging number of pickleball players in Forest Lake — there are more than 120 today — began pushing for courts of their own.

In May, Forest Lake agreed, converting a large concrete slab that once was meant to be the foundation of an outdoor hockey rink into a permanent set of pickleball courts. The project cost about $50,000, Muscha said. Allina Health and the Forest Lake YMCA contributed to the effort.

"On the first day of being open we had a line of pickleball players desperately waiting to play," said Tim Schingen, chairman of the city's Parks, Lakes and Trails Commission. "This should be a great park and recreation asset to the Forest Lake community for several years."

Said Forest Lake Mayor Ben Winnick: "This has been a great project that maximizes the use of an existing space at Fenway Park."

'So much fun'

On a recent morning, the courts were nearly filled with doubles teams as more than 20 players thwacked the ball, which looks like a slightly heavier version of a Wiffle ball, back and forth. Games were competitive, scores were kept, but apparently pickleball etiquette frowns on trash talk.

"Oh no. No trash talk," exclaimed Judy Johnson, Denny's wife. "But, of course, I want to win."

Anna Hobbs of Chisago City has been playing the game for four years, ever since taking a class at the Shoreview Community Center.

"It's so much fun, you don't realize you're getting exercise," she said.

The game can be played indoors or out, as singles or doubles. Bob Minter of Lino Lakes prefers playing outside, where the wind can make the movement of the ball more of a challenge.

"I started this when I retired," he said. "I was always very active."

Use of the courts is free and they are available on a first-come, first-served basis. Generally, the courts are open from 9 a.m. to 4:30 p.m., Monday through Friday.

An official grand opening has been scheduled for Aug. 4 from 4 to 5 p.m., Muscha said, with expanded daily and weekend hours to follow. For more information, check with the Forest Lake Parks and Recreation department at ci.forest-lake.mn.us/178/Parks.

Johnson, who said he began playing the game in Florida in 2002, said he appreciates that city leaders responded favorably to his group's enthusiasm. While played by people of all ages, the sport has really clicked with baby boomers and older folks.

"They wanted some active adult activities," he said. "And tennis is too big of a court for us at this age."

James Walsh • 651-925-5041