Joseph Pilates invented a variety of machines, based on spring-resistance, that could be used to perform these exercises.

There is a famous story about Pilates' inspiration for his unique apparatus. Before World War I he was touring England as a circus performer and professional boxer, and even teaching self-defense to the Scotland Yard police force. But when war broke out, he found himself interned in England as an enemy alien on the Isle of Man.

The health conditions in the internment camps were not great, but Pilates insisted that everyone in his cell block participate in daily exercise routines to help maintain both their physical and mental well-being. However, some of the injured German soldiers were too weak to get out of bed. Not content to leave his comrades lying idle, Pilates took springs from the beds and attached them to the headboards and footboards of the iron bed frames, turning them into equipment that provided a type of resistance exercise for his bedridden "patients."

These mechanized beds were the forerunners of the spring-based exercise machines, such as the Cadillac and the Universal Reformer, for which the Pilates method is known today. Pilates legend has it that during the great flu epidemic of 1918, not a single one of the soldiers under his care died. He credited his technique (which he called "Contrology") for the prisoners' strength and fitness — remarkable under the less than optimum living conditions of internment camps, which were hit especially hard by this deadly flu.

After the war Pilates returned to Germany, where he worked for a few years training police officers and collaborating with dancers and other experts in physical exercise. However, around 1925 he decided to emigrate to the United States. He met his future wife and dedicated teaching partner, Clara, on the boat to New York City. Together they opened the first Body Contrology Studio on Eighth Avenue at 56th Street in Manhattan, in the same building as a number of dance studios.

For the rest of his life, he continued to develop his exercise system and to create new pieces of equipment for it. In this task he was evidently not only inventive, but also resourceful. It is said that his first Barrel was constructed from a beer keg, and he used the metal hoops from the keg to make his first Magic Circle.