You're going to be sore tomorrow," said Master Yi, who in his day job is Dennis Yi, 37, a graphic designer for Mellon bank. Master Yi had just given me an introductory lesson in Tae Kwon Do (Korean karate) at the Young Brothers do jang (house of discipline) in Ross.

	Andy Starnes, Post-Gazette Senior instructor Josh Ryer demonstrates a block and punch during class at United Kenpo Karate in Shadyside last week. Click photo for larger image. Related article Martial arts: Styles to suit every taste

He was right.

"You're going to be sore tomorrow," Sifu (master) David Slaughter, 43, told me the next night after I took an introductory class in kung fu at the Rothrock's Kung Fu and T'ai Chi studio in Wexford.

I was so sore I could barely sleep that night. Muscles I hadn't used in years ached and throbbed. Muscles I didn't know I had ached and throbbed.

I'm old and fat now, but I used to think I knew what it meant to be physically fit. I was a Green Beret. I ran three marathons, including the Pikes Peak (up and down the mountain). I still work out four to five times a week, at what I had thought was a fairly high degree of intensity. But I've never been more whipped after a workout than I was after these two martial arts classes.

And though most people who study martial arts do so for reasons other than physical fitness, there may not be, as I've discovered, a better way to get or stay in shape.

All around improvement

"Tae Kwon Do is a way of life," said Master Young Bo Kong, proprietor of Young Brothers Tae Kwon Do. "You are in total control of yourself."

"When I was young, I was very shy," Dennis Yi said. "This helped me a lot."

Martial arts instructors are all slim, agile, and -- despite the absence of bulging muscles -- very strong.

Those who've practiced a martial art two or three times a week for six months or more report often dramatic losses of weight, as well as increases in stamina and improvements in balance and agility.

For some, practicing a martial art also is an effective form of physical rehabilitation.

Tim Muller, 48, who works for the Federal Aviation Administration and lives in the North Hills, was suffering from rheumatoid arthritis -- an inflammatory disease that causes stiffness and lack of function in the joints -- when he began practicing kung fu under Mr. Slaughter's tutelage.

"Between the doctors and Sifu Slaughter, I saved all my joints," he said. Mr. Muller also lost 50 pounds, and says his energy level is "off the charts."

Lake Fong, Post-Gazette Cullen Steele, 6, of Ross aims a kick at a target during class at Young Brothers Tae Kwon Do in Ross last week. Click photo for larger image.

"Most people who do this drop a little weight," said Kevin Groll, 23, an engineer from East Liberty who studies Muy Thai at the Martial Arts Academy of Pittsburgh in Turtle Creek. "Physical stamina goes way up. It's a pretty intense martial art."

Stephanie Rogers, 27, a legal researcher, has been practicing kung fu for two years. She's lost 30 pounds, her coordination is better and her overall improvement in physical condition caused her to seek out other forms of exercise.

"After I lost all the weight, I started jogging," she said.

Martial arts training is a good way to get fit for people who lack the self discipline to go to the gym regularly, said Master Young Bo Kong.

"You go to a health club, you have discipline problems," he said. "Having an instructor helps you push it."

Dave Shumsky, 38, an HIVC technician who's been practicing kung fu for two years, emphatically agrees:

"Before this, I'd joined the Y[MCA], but I only went six times," he said.

Mr. Shumsky attends kung fu classes three to four times a week. "I'd be here every day, but my wife would kill me," he said.

Because of its emphasis on discipline and respect, studying a martial art is especially valuable for young children.

Respect is emphasized most locally at the Young Brothers Tae Kwon Do do jangs. Before entering the do jang, students bow to the Korean flag, and bow to every master on the floor. Repetitions of pushups and situps are counted out in Korean. Students "sir" their instructors as often as Marine recruits "sir" their sergeants.

But respect for their art, for their instructors and for their fellow students are hallmarks of all martial arts studios. (After my kung fu session, every student in the class came up to me individually to tell me how well I had done. Their courtesy greatly exceeded their accuracy.)

Lynda McCabe of Franklin Park thought martial arts training would help improve the focus of her 11-year-old son John, who has autism. Three years of Tae Kwon Do training for John have proved her right.

John's school work and his behavior both have improved markedly since he began studying karate.

"It's taught him a lot about respect," his mother said. "We go to restaurants, and he says 'thank you, ma'am,' to the waitress."

But though martial arts training is especially valuable for the young, people of all ages can benefit from it.

There isn't a soul under 60 in the T'ai Chi class David Slaughter teaches at Club Julian in Ross on Thursday afternoons.

T'ai Chi Chuan is one of the oldest of the martial arts, with moves done in slow motion, like a dance.

"It's like a moving meditation," said William Kraft, 67, a psychology professor at Carlow University, who's been practicing T'ai Chi for five years. "It helps me focus."

Kay Rogik, 70, of Glenshaw, has been practicing since last September.

"For me, it was for balance and for regulating blood pressure," she said.

Carol Shire of Pine is a former dancer.

"I came here to try to keep the balance and rhythm of movement," she said. "Now that my knees are shot, this is my speed."