NOVELTY - The machine (1) has a processing unit (7) managing and controlling the machine, and a sensor unit (9) for transferring information about a machine operating state to the processing unit. A user interface (10) is equipped with display units (11) for displaying a machine current operating state, and manual control units (12) are provided for machine functions. Optimization units (19) are controlled by the processing unit, and modify the display units and the manual control units, when variations occur in a machine operating parameter e.g. belt incline, detected by the sensor units.    USE - Exercise machine e.g. treadmill, for assisting user exercises by walking and running on a belt. Can also be used for an exercise bicycle, an elliptical movement machine and a rowing machine.    ADVANTAGE - The configuration of the machine allows the user to keep a gaze on the display while exercising, even with moving images, without feeling troublesome sensations and without risking loss of balance, thus ensuring the synergic effect of increasing comfort and increasing the accessibility of the controls, and hence increasing the safety of the user. The machine allows the user to operate the controls on the screen easily and without any difficulty while exercising, even when exercising at high speeds, and even in critical situations such as sudden loss of balance. The machine allows the user to concentrate better and to immerse of the user in the multimedia content that can be shown on the display while exercising, above at low speeds. The machine has simple structure, and is easy to make in practice and inexpensive, and operates safely and effectively.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a process for optimizing a user interface of an exercise machine.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of an exercise machine.    Exercise machine (1)    Processing unit (7)    Sensor unit (9)    User interface (10)    Display units (11)    Manual control units (12)    Optimization units (19)