Rock the bells: Kettlebell fitness craze lifts off

• Modern kettlebells descend from Russian version in 1700s
• Indianapolis home to two master instructors
• Intense workout can burn about 600 calories a half-hour

The Indianapolis Colts do it. So do Hollywood beauties like Jennifer Aniston and Jessica Biel.

It burns more calories in 30 minutes (606 calories, to be exact) than 30 minutes of cardio kickboxing plus 30 minutes of spinning combined (531 calories total).

Kettlebell, once an exercise reserved for men wanting to build massive muscle, has become one of the hottest — if not the hottest — fitness trends around.

The Indianapolis area is home to the queen of KettleWorX, Laura Wilson, who is developing a trademarked kettlebell program and DVDs.

It's also home to Marty Mills, ranked the nation's No. 1 Russian Kettlebell Challenge instructor, whose Greenwood, Ind., kettlebell gym, The School of Strength, is one of the largest in the country.

Life Time Fitness in Fishers, Ind., just became the worldwide pilot for KettleWorX, where Wilson will lead the classes, including a resistance, cardio and core variety.

The fitness industry has known for years the benefits of this intense workout using weighted balls (originally cast-iron) with handles that got their start in Russia in the 1700s.

"I'm amazed kettlebells have not made a bigger splash on the mass market," said Wilson, 36, who is the director of programming for fitness company Pivotal 5 in Chicago, which owns KettleWorX.

But they are making a splash now. Hollywood has a little something to do with it. Stars like Aniston, Biel and Penelope Cruz have recently been seen immersed in the kettle craze.

Plus, who wouldn't want to get a 60-minute workout for 30 minutes work?

"And you will build muscle, not just crazy muscle," said Wilson, referring to those muscle-bound men many people associate with iron.

And not just muscle.

The American Council of Exercise recently studied the benefits of the kettlebell and found that in eight weeks people could increase their cardio fitness by 17 percent.

There was also a 13.8 percent increase in aerobic capacity and the most dramatic increase came in abdominal core strength, which was boosted by 70 percent.

"(Kettlebell is the) equivalent to running a 6-minute mile pace," said Dr. John Porcari, leader of the study, in the council's publication FitnessMatters. "The only other thing I could find that burns that many calories is cross country skiing up hill at a fast pace."

Mills agrees that kettlebell is the workout of all workouts.

"No other training tool," said Mills, "works the entire body and every performance system of the human body like the kettlebell."