Once a week, Kari Gray heads over to what she calls "the best-ever gym class." The 25-year-old Minneapolis resident isn't going to a fancy health club or plush spa. She's on her way to Bryn Mawr Park to play kickball.

That's right, kickball, the same game that once was the staple of grade-school gym classes is the activity to which Gray refers. The game is booming among adults who are attracted by its snappy hourlong format, the fact that players don't need extensive athletic backgrounds -- in fact, some would argue that being a hard-core jock actually can work against you -- and the ultra-low-key attitude.

"It's a place you can be silly without looking stupid," said one of Gray's teammates, Chi Ngo, 33, of Minneapolis.

Although kickball has been played recreationally for decades -- legendary war correspondent Ernie Pyle noted soldiers playing it during World War II -- it's relatively new to the ranks of organized leagues.

The first local league is believed to have been formed in St. Louis Park in 2004. Now you can't turn around near a softball field without seeing people kicking the spongy, brightly colored balls. The Minneapolis Park & Recreation Board is sponsoring 17 leagues this summer that involve about 2,000 players. St. Paul is kicking off (so to speak) another round of leagues in mid-August. In addition, nearly every suburban park program includes at least one.

There also are private leagues, including ones operated by the Cities Sports Connection (www.myteamsports.net), a Burnsville company started by brothers Pat and Matt Barbatsis.

"We've seen a lot of growth in the last six or seven years," Pat Barbatsis said. "It's great watching adults have the fun and excitement of an 8-year-old."

In his third year of league play, Nathaniel Smith, 29, of Minneapolis, said that kickball serves a vital social function.

"For people like me -- singles in their late 20s or early 30s -- this is like the bowling leagues in the 1950s and '60s," he said. "Bowling was a chance to get out of the house and get together and relax with friends. That's what we do. Plus we get a little exercise."

There are a couple of highly competitive leagues, Barbatsis said. But most leagues -- especially the coed ones that require lineups to be evenly split between men and women -- are focused more on having fun.

"It's not that we're not competitive," Smith said of his team, which plays in a coed league. "We want to win, but our day isn't ruined if we lose."

A fast-paced game

Kickball, which originally was called "kick baseball," is played on a softball field, and the rules are much the same. The games last seven innings or 55 minutes, whichever comes first. Because leagues schedule multiple games each evening on the same field, the time limit is strictly enforced.

Things move along briskly. An umpire calls balls and strikes -- the latter being defined as a zone that extends one foot either side of home plate -- and walks are possible. But unless the pitcher, who rolls the ball toward home plate, is way off the mark, most kickers go after the first or second pitch they get.

Some kickers stand only a step or two behind the plate and wait for the ball to come to them, while others move all the way to the backstop and come charging at the ball. The force of the resulting impact can be deceptive, said Stephen Hough, 24, of Minneapolis, who also plays in a soccer league.

Because the ball is squishy, "it's actually harder to kick than a soccer ball," he said. "Kicks die in a hurry. You kick it thinking that it's going to be over everyone's head, and then the center fielder just stands there and catches it."

The squishy ball is the game's great equalizer, said Dan McIntosh, 30, of Minneapolis.

"Everything you kick into the air, you think it's going to go farther, but it really is just increasing the odds that someone will catch it," he said. "The key is to keep the ball on the ground and run fast. That's why many of the women do so well."

The game's rapid growth also has been fueled by a quick learning curve, Barbatsis said. If you can kick, run and catch a soft rubber ball by using both hands to trap it against your stomach, you've pretty much mastered the basic skill set.

"It doesn't require skills that you spend years practicing," he said. "It's got great accessibility. Anybody can play it."

There is room for improvement, however. Serena Kuo, 28, of Minneapolis, is playing in a league for the first time this summer. She said her play has gotten much better in the two months since the league started.

So, how good is she?

"Well," she said after pondering the question, "I'm better than I was in fourth grade."

Jeff Strickler • 612-673-7392