Physiologic Aspects of Bicycling

Abstract

The metabolic energy cost of moderate-intensity cycling is largely represented by the whole body Vo2 of the cyclist. This measure can be and is used to assess the relationships between energy cost and technique, somatotype, fitness level, biomechanical factors, and cycling resistance. Maximal Vo2, the upper limit for metabolic activity that depends on "aerobic" energy production, is sufficiently high in well-trained cyclists so as to not constrain endurance performance. In contrast to endurance athletes in other sports, the competitive cyclist must also possess the ability to sprint and quickly accelerate from an already high level of energy output, which are actions that require large contributions from "anaerobic" energy sources. In this article, the basis of these energy production processes has been reviewed and techniques for their measurement have been described. In addition, the sources of resistance to forward motion of the bicycle have been described with emphasis on how these forces limit performance. With this background, the physician and physiologist are prepared to explore special areas of cycling technology and specific medical complaints induced by bicycle exercise.