a safety feature can be built into the system wherein when a users grip on the user interface is relaxed the first and second valves on the resistance system close reducing the load to the user thus reducing the chance of injury referring to fig2 user interface 6 is depicted is a straight rod shaped bar however user interface 6 could take many forms it could be a handle a curved or bent bar a flat padded surface a curved or circular padded surface or any other piece capable of engaging a portion of the body user interface 6 can move on a track such as one described in the co pending applications or in free space user interface 6 can be attached to any cable pulley chain rope elastic band flexible member based fitness machine by using an eyelet such as a clevis 3 a user can enter data into the user interface 6 using keypad sensor 15 keypad sensor is coupled to microprocessor 11 and user data can be stored in microprocessor 11 the user can also enter data regarding which body part he she will be using to move the user interface 6 and what type of motion or what exercise is desired user recognition can also be done through other means such as a scrolling device or a fingerprint.