Abstract
Exercise offers a unique stage from which to study and teach the integration of physiological systems. In this article, the process of matching O2 transport from air to its ultimate consumption in the contracting cell is utilized to integrate the workings of the cardiac, smooth, and skeletal muscle systems. Specifically, the physiology of exercise and the maximal oxygen consumption (V˙o2 max) achieved through the precise linking of these three muscle systems are utilized to highlight the complexity and importance of this integration. Smooth muscle plays a vital “middleman” role in the distribution of blood-borne O2 to the appropriate area of demand. Cardiac muscle instigates the convective movement of this O2, whereas skeletal muscle acts as the recipient and ultimate consumer of O2 in the synthesis of ATP and performance of work. In combination, these muscle systems facilitate the remarkable 15- to 30-fold increase in metabolic rate from rest to maximal effort in endurance-type exercise.