The workout burns 800 calories per hour, according to Muscle and Fitness magazine.
No martial arts experience is needed. Class members learn punching, blocking and kicking techniques but don't fight each other, and they can wear loose, comfortable clothing.
Cardio Karate classes are offered by members of National Association of Professional Martial Artists.
Classes at Thompson's utilize a 20-minute aerobic routine with karate blocks and kicks, a short break, and a 20- to 25-minute workout on punching bags. Participants wear hand wraps for the first half of the workout, then change to boxing gloves for the second portion.
The workout is a great stress reliever, Kendra Thompson says.
"You can come in and take your frustrations out on the bags," she says.
High-energy dance music keeps the participants motivated, she says. The song "Kung Fu Fighting," played halfway through the workout, is a favorite to get things moving.
Trina Johnston, a Maugansville resident who takes Cardio Karate two afternoons a week, says the workout is the best she's found.
"I'm in better shape now than I was in high school," says Johnston, a 29-year-old mother of two. "I have good muscle tone, I feel healthy and it takes my stress away."
Johnston, who had studied karate for the past three years, stopped taking it because of a knee injury. She says Cardio Karate has strengthened her knee.
She says the workout has the same principles as regular karate, except that you are fighting a punching bag.
"In karate I didn't put everything into it, because I was afraid I'd hurt somebody," says Johnston, who describes herself as a bit timid. "Now I actually work out harder, because I'm hitting a bag instead of a person."
Christie and Barry Hawbaker of Mercersburg, Pa., say they appreciate Cardio Karate because it's a workout they can do together.
"It's really helping me to get in shape," says Christie Hawbaker, 25. "I have a lot more stamina, and I don't get tired as quickly."
She says she has had trouble sticking with an exercise program in the past, and that working out with her husband helps her stay committed to her goal.
Barry Hawbaker, 26, who also takes karate, says Cardio Karate has given him better stamina in that activity.
"I don't get tired as fast, and my energy level is way up," he says.