strong hold; Used as a strength-training method in czarist Russia, kettlebells are swinging into the modern exercise world.

Byline: Lynn Snowden Picket

You will learn to do this," said Pat Manocchia, owner of La Palestra, the beautifully appointed, exclusive gym off Central Park on Manhattan's Upper West Side. He picked up a kettlebell-a globular chunk of cast iron with a large handle and flat base, a sort of teakettle minus the spout-and proceeded to demonstrate the Traveling Woodchopper. While expertly flinging a 35-pound kettlebell across his upper body, he crossed the mammoth space, lunging deeply with each step. Fearful that one slip of his grip could result in a broken nose, I discreetly took a step back. A quick glance around the room revealed eighteen equally petrified-looking people, ranging in age from 27 to 60. There was Marjanne, a Manhattan restaurant manager; Mark, a senior fashion-house executive; Marco, an NFL football player; and Adam Duritz, the lead singer of Counting Crows. We had signed up to be gym rats in an eight-week study designed by the directors of Kettlebell Concepts, a company that instructs personal trainers, to compare the effectiveness of traditional weights versus kettlebells.

Dating back to the earliest physical culture in czarist Russia, an era of baggy woolen exercise clothing and handlebar mustaches, kettlebells are the very definition of "old school." Some claim they're the fitness secret to the lengthy Soviet stronghold on Olympic medals and were the preferred training method of the KGB. In recent years, kettlebells have enjoyed a renaissance in Asia, where martial artists use them to gain speed, strength, and power without adding bulk, which is exactly why they've also caught on among American ballet dancers. Now kettlebells are storming into elite gyms across the country.

The promise of a kettlebell physique-long, lean, and strong-is why I willingly, even eagerly, handed my body over to science. But as I went through the preliminary tests to measure strength and flexibility, I wondered what I could reasonably expect from a program of just two weekly one-hour sessions, with ...