Various embodiments of the present invention provide (a) an inexpensive apparatus enabling the measurement of power dissipated by the rider of a cardio-fitness station (or any other stationary bicycle) that does not depend on manufacturing tolerances or machine condition variations, and (b) a method of using the data measured by such an apparatus to improve the accuracy of exercise condition settings by implementing the invented apparatus into a closed-loop control system which improves the quality of the exercise experience and enhances the adoption of exercise on a cardio-fitness station employing this as a community activity.