John Du Cane could qualify for Social Security, but the 62-year-old publisher and entrepreneur is seriously ripped.

"Punch him," implores friend and business partner Pavel Tsatsouline during a recent meet-up with Du Cane at Dayton's Bluff Recreation Center in St. Paul. "Seriously, go ahead and punch him in the stomach. It's OK."

Du Cane's wife of 27 years, Andrea, agrees.

"Really, it's OK. We grate cheese on his abs at home," she teases.

What the heck -- a quick punch to Du Cane's midsection indeed rings back a super-human thump.

"John is in unbelievable physical shape," Tsatsouline says. "Most guys half his age would not be able to do the things he can."

Du Cane's slight frame -- 5 feet 11, 160 pounds -- belies his strength and muscle definition. His sculpted body is the result of a combination of nutrition and daily strengthening workouts that include body weight exercises and, of course, kettlebells.

Du Cane is a walking endorsement for the kettlebell fitness movement, which he started 11 years ago with Tsatsouline in the Twin Cities. It has grown to become a nationwide phenomenon .

Kettlebells look like cannon balls with handles. They're heavy, 18 pounds and up. In the 1700s, smaller kettlebells were used as weight measures in Russian produce markets.

Reportedly, farmers started throwing them around for fun. In the 20th century, the Soviet military used kettlebells for physical training and conditioning. Since the 1940s, kettlebells have been continually used for fitness and competition in Russia and other eastern European countries.

Kettlebells probably were used in fitness regimes in the United States in the 1960s, but it wasn't until Latvian Tsatsouline met Du Cane that kettlebells truly emigrated to the United States.

"When I listened to him talk about the benefits of kettlebells, and how they were used by elite athletes and the military in Russia, I thought it was something we could try," Du Cane says. "So, I said, 'Let's make the kettlebells ourselves!'"

The two men commissioned a foundry in St. Paul to make their Russian-style cast-iron kettlebells. (Today, they are made in China.)

By 2001, they were ready for a kettlebell blitz, which included Dragon Door, Du Cane's company, publishing Tsatsoulines' book "The Russian Kettlebell Challenge: Xtreme Fitness for Hard Living Comrades." They also released a how-to video and created the first kettlebell certification program in the United States.

Their first customers were hard-core lifters and military, police and firefighters. Then medical doctors and other health professionals started getting certified in their kettlebell system.

Word spread, especially after key endorsements by Rolling Stone magazine and other publications. By 2004, their Russian Kettlebell Challenge (RKC) really started to take off.

RKC's success has spawned about a half-dozen serious competitors with their own training and certification systems. Du Cane says, bring it on.

"I personally feel the more the merrier," Du Cane says. "Let's make the pie bigger rather than squabble about what there is to share."

He's a meditative man

Du Cane's response is consistent with his intention to face all of life with equanimity.

For much of his life, Du Cane has studied meditation and has taught classes in the "soft style" martial arts, particularly tai chi and qigong.

"I believe I've been on a quest since my 20s to be an admirable human being," he says, wearing the usual loose-fitting black, long-sleeved shirt and black pants that have become his spiritual uniform, of sorts. "I value physical cultivation greatly. I have a value that a strong, powerful and energetic body is something to be both respected and sought after."

Aside from regular visits to a St. Paul martial-arts studio, Du Cane's quest to maintain his physique doesn't include a gym membership. Instead, he performs quick bursts of action throughout the day with a variety of fitness implements that are collected in corners of his home in St. Paul and office in Little Canada.

"For a while, we had a pull-up bar in the living room -- until it almost fell into a leaded-glass window," says Andrea Du Cane sheepishly. "In another corner, we've got resistance bands and a chi machine. You can't walk in our house and not see what our passion is."

Du Cane says that as people get older, they lose a certain amount of supple strength as their ligaments, joints and tendons start to "dry up."

So, he's working with his aging body -- instead of against it -- by increasingly favoring exercises that use only the weight of his body for resistance. He highly recommends his beloved pull-up as a favored option.

"It builds tremendous upper-body strength," he said. "But most people don't realize how much it also develops the abdominals."