Cabinet Magazine posted a great feature on the secret history of Cybex-like exercise machines. Apparently, the first "gym" filled with mechanical fitness contraptions was built by Swedish physician Gustav Zander in the late 19th century.

Zander's mechanical horse was an early version of the Stairmaster, a contraption for cardiovascular fitness designed to imitate a "natural" activity. His stomach-punching apparatus evokes contemporary "ab-crunching" machines. What makes Zander so important, for anyone trying to trace the Cybex family tree, is what happened when his machines, created in a European cultural context, immigrated to the US in the early twentieth century. They are prototypes of the workout equipment now ubiquitous in American life.

Source: cabinetmagazine.org