Routines are carefully structured to gradually increase, then decrease, heart rate. The last 15-20 minutes of each class is devoted to strength building and toning, Missett explains.
Top music from various genres is matched to the routines. "Music is a great catalyst for movement," says Missett, who choreographs the routines (they're also reviewed by an exercise physiologist). The music and routines change often, to keep things fresh and keep muscles challenged.
This year, Jazzercise won a thumbs-up from Consumer Reports. It's the only exercise program rated by the magazine that satisfied all its criteria for a well-rounded workout.
During a 30-minute Jazzercise workout, a 200-pound person can burn 273 calories, according to Consumer Reports. Not only that, but Jazzercises provides cardiovascular benefits along with a resistance workout that works both the upper and lower body. It's also weight-bearing exercise (the kind that helps protect against bone loss).
"Jazzercise is still around because it's so good," says Gerald Endress, MS, a clinical exercise physiologist and director of the Duke Diet and Fitness Center at Duke University Medical Center in Durham, N.C.
"Jazzercise is made to be fun, but to also improve aerobic capacity, strength, and endurance. And if you like that kind of jazzy dancing, it's for you. It says a lot that Jazzercise has been around so long."
Every(wo)man's Fitness Program
"Dancing is moving ... anybody can dance," says Josie Gardner, a former ballet dancer who's now an exercise physiologist and spokeswoman for the American Council on Exercise. "You can dance sitting in chair, dance with your friends. It doesn't matter whether you do five or 10 minutes at a time or more. Dancing makes people feel good, and it's fun."
Gardner lives in Massachusetts, where dance clubs are tradition.
"You can find 500 couples in there ballroom dancing. You can work up a good sweat if you're doing it all night," she says.
What kid doesn't like to dance? Step into any arcade: Kids are all over the "reactive dance pads" -- soft floor pads that look something like the old Twister game.
You can buy them for home use, too. Plug the pad into your computer and it lights up, guiding where your feet should go.
"Dance pads are a great workout," Gardner says. "Kids kind of dominate them now, but anyone can do it."