Table of Contents

Human Power and Propulsion




Age and Gender also influence the work output of people. The curves opposite show data on the maximum oxygen consumption rate (which is directly related to the steady state power output) of different subjects. The power output capability is about 20% larger for adult men than adult women, and for both genders the peak of capability occurs between 20 and 35 years of age.

Part of the gender difference seems to be due to the lean muscle weight, which is less in women, and to the hemoglobin content of the blood (and hence oxygen transport capability) which is also less in women.

From: Abbott & Wilson, "Human-Powered Vehicles,"
Human Kinetics (1995)

The magnitude of the decline in oxygen consumption rate with age is dependent on the general activity level of the person studied. It is greater in sedentary people as compared to active people by a factor of three. In athletes, the time at which the oxygen consumption rate starts to decline may also be delayed until 40 years of age.

Estimates of the efficiency of participants in a cycling marathon yield overall mechanical efficiencies that are between 17% and 20%. For a typical automobile, efficiencies are on the order of 15% to 20%. In both cases, the rest of the chemical energy consumed appears as waste heat.