… or an on-the-level workout? Truth is, it’s a little of both. While most of us never heard of it before celebs like Carrie-Ann Moss and Jennifer Anniston began dropping the P-bomb in interviews (Moss described her training regimen in prepping for The Matrix: “lots and lots of Pilates”) , Pilates has been well known to athletes, especially dancers, for nearly 80 years. Here are some highlights from its colorful history:

• German founder Joseph Pilates had a noble motivation for designing his get-fit regimen: so he could best the bullies who tortured him at school. Born a sickly weakling, he was a natural target, so he studied anatomy and worked out like a maniac. By age fourteen, not only had the bigger kids stopped taking his lunch money and calling him “Christ killer” (a clever play on his last name), he was in such good shape that he was asked to pose for anatomy charts.

• After distinguishing himself as a pugilist, swimmer, diver and gymnast, WWI found him interned at a camp for “enemy aliens” in the UK. Also trained as a nurse, Pilates began to develop a system of physical rehabilitation which wounded soldiers in the camp’s hospital could perform in their beds — thus the Pilates Reformer (pictured above), based on modified WWI-era hospital beds.

• Pilates founded a famous training studio in New York in 1926, later publishing a book about his new method, modestly titled Your Health: A Corrective System of Exercising That Revolutionizes the Entire Field of Physical Education.

• Known as a lover of whiskey and women as well as a fitness freak, Pilates was mildly notorious for his “hands-on” training sessions.

• Another lover of women and Pilates, actor Hugh Grant, has claimed that he has “muscles of steel and could easily deal with giving birth” thanks to his workouts.