As long as we're talking about exercise without motion, I thought I'd mention these Jetson-like skates that allow a person to walk in virtual worlds without loco-motion:
A pair of motorised roller skates that cancel out a person's steps could let users naturally explore virtual reality landscapes in confined spaces. . . .
Each shoe is mounted on top of a set of three motorised rollers and is connected by cable to a computer on the user's back. This computer controls both the motion of skates and a head-mounted display that shows the user a virtual landscape.
As the wearer walks forwards, the connected computer controls the rollers under their feet, cancelling out their strides. The computer also updates the visual display to create the illusion of walking through the virtual world.
