Performance factors in bicycling: Human power, drag, and rolling resistance

The maximum power that an athlete can produce is a question of the time domain of interest which can be hours or just fractions of a second in a given discipline (human power spectrum). The human body functions as a “biological machine”. Like any other motor the “muscle force machine” has a limited efficiency. In every sportive movement another combination of the loading types influences the performance. Consequently, there is a diversity of human performance factors. A muscle cell’s work is the conversion of useful chemical energy to mechanical work. There are basically three different types of energy supply modes available to the human organism. Two of the body’s three energy systems do not require oxygen for the production of adenosine triphosphate (

ATP

). The production, the transport and usage of lactate, which results from glycolysis and glycogenolysis, represents an important means to link glycolytic and oxidative metabolism (

lactate shuttle

). Various physiological variables are influenced by the working status of the body and can be used for performance diagnosis and training control.

The equations describing the necessary mechanical power in cycling for overcoming the rolling resistance, the air resistance, and the power necessary for climbing a slope are described as well as the measurement of power-output by means of mechanical cycle ergometers. Depending on the discipline it can be absolute power or power with respect to the body weight which is of dominating relevance. Power values obtained by cycling athletes of various levels and cycling disciplines are discussed on the basis of results published in the literature.

Individual optimization of drag by means of wind tunnel measurements is essential for high performance. Measurements of drag in elite cyclists should be done during effort because static measurements underestimate drag in real competition or training situations. The position of the athlete, his body dimensions, and the aerodynamic features of the bicycle and the equipment have a pronounced impact on the performance.