Biochemistry of Exercise

Abstract

The energy required to perform the mechanical work of exercise is derived from the hydrolysis of adenosine triphosphate (ATP). At rest, skeletal muscle cells possess only limited quantities of ATP and other high-energy phosphate molecules. If exercise is to be continued for more than a brief period of time, ATP must be continually replenished through the metabolism of fuels—primarily fats and carbohydrates. The aerobic metabolism of fuels consumes oxygen (O₂), produces carbon dioxide (CO₂), and generates large quantities of ATP per carbon atom. In the absence of O₂, ATP may also be produced via anaerobic metabolism. This process generates much less ATP per carbon atom, but does not require O₂. It does produce lactic acid, which buffers bicarbonate to form CO₂. Familiarity with this biochemistry is essential to an understanding of the physiology of exercise.