Abstract: A physical exercise video system includes a physical exercise machine (22), a video system (24) and an interface module (26). The video system (24) has a computer (28) and a removable cartridge (34). The interface module (26) is interposed between the computer (28) and cartridge (34), and provides interactive communication between the computer (28) and exercise machine (22). A communication protocol governs this communication, and includes specifications for status and command data packets. The video system (24) and exercise machine (22) can be selectively operated as either stand-alone units, or in an interactive exercise mode, wherein the exercise data generated by the exercise machine (22) affects the output of the video system (24), and may also be stored in memory within the interface module (26). The video system (24) controls the operation of the exercise machine (22) generally, and specifically, controls the load resistance imposed in opposition to the movement of pedals (66).