Pilates, an old exercise regimen made fashionable in recent years by athletes and movie stars, builds strength and flexibility without adding bulk.

Unlike conventional weight training, which emphasizes repetition on one muscle group at a time, Pilates focuses on a series of precise, controlled movements that work muscles in several positions. The result: a longer, leaner look such as that seen on such Pilates converts as Madonna and Julia Roberts.

The low-impact exercises concentrate on strengthening the abdomen, lower back and buttocks. They are done on floor mats or by using several pieces of equipment that look like medieval torture devices but are actually gentle on the body.

A Brief History of Pilates
The basic tools of the system brought to the U.S. in the 1920s by its German immigrant creator, Joseph H. Pilates, use springs and pulleys to vary resistance. The most common, called a Reformer, consists of stirrups for either hands or feet and a bed-like platform that slides along a track. The Cadillac, or trapeze table, is surrounded by a metal frame and includes a push-through bar, a trapeze bar and leg straps.

Pilates had a lifelong interest in body conditioning. As a frail child determined to get stronger, he worked to become an accomplished skier, diver, gymnast and boxer. He developed the exercise method while he was detained in an English internment camp for German citizens at the onset of World War I.

Pilates opened a studio in New York City in 1926. Because many of the exercises focused on posture and body alignment, Pilates' approach quickly drew the notice of dancers, who also enjoyed being able to develop strength and flexibility without adding bulk.

In recent years Pilates has become the rage at health clubs. In addition to professional performers, housewives, grandparents—even pregnant women—are benefiting from the technique.