A trained cyclist can produce about 400 watts of mechanical power for an hour or more, but adults of good average fitness average between 50 and 150 watts for an hour of vigorous exercise. A healthy well-fed laborer over the course of an 8-hour work shift can sustain an average output of about 75 watts.[1] The yield of electric power is decreased by the inefficiency of the human-powered generator, since all real generators will incur some losses during the energy conversion process.
While some exercise equipment has been fitted with generators, the amount of energy collected is of low value compared to the cost of the conversion equipment.[2]