(US6056670-A)      The exercise machine (10) has an exercise input unit (31) to transform human exercise (pref. involving alternate extensions and contractions of limbs) into a predetermined motive force. This force is then used to drive a controllable load. A sensing circuit senses power coupled into the load through the exercise input unit.    A control circuit controls the load so as to require the user to provide a selected amount of power to the exercise input unit. The exercise machine operates to provide a constant and quantifiable energy exercise rate. The machine is powered by the user's action when in use and by a rechargeable battery when not in use.    ADVANTAGE -   No need for external power source. Maintains metabolic energy consumption constant at predetermined rate regardless of user's weight.    (US6176813-B1)      The exercise machine (10) has an exercise input unit (31) to transform human exercise (pref. involving alternate extensions and contractions of limbs) into a predetermined motive force. This force is then used to drive a controllable load. A sensing circuit senses power coupled into the load through the exercise input unit.    A control circuit controls the load so as to require the user to provide a selected amount of power to the exercise input unit. The exercise machine operates to provide a constant and quantifiable energy exercise rate. The machine is powered by the user's action when in use and by a rechargeable battery when not in use.    ADVANTAGE -   No need for external power source. Maintains metabolic energy consumption constant at predetermined rate regardless of user's weight.    (US2001011052-A1)      The exercise machine (10) has an exercise input unit (31) to transform human exercise (pref. involving alternate extensions and contractions of limbs) into a predetermined motive force. This force is then used to drive a controllable load. A sensing circuit senses power coupled into the load through the exercise input unit.    A control circuit controls the load so as to require the user to provide a selected amount of power to the exercise input unit. The exercise machine operates to provide a constant and quantifiable energy exercise rate. The machine is powered by the user's action when in use and by a rechargeable battery when not in use.    ADVANTAGE -   No need for external power source. Maintains metabolic energy consumption constant at predetermined rate regardless of user's weight.