Exercise induces changes in the body of the athlete. These changes are varied and depend upon the nature of the activity. Endurance athletes, such as marathon runners and long distance cyclists, must supply their muscles with oxygen, swiftly remove the waste products of metabolic activity from their tissues, and quickly propel their bodies along for mile after mile. In contrast, weight lifters and sprinters need to generate sudden explosive power in their arms and legs in order to propel massive weights vertically upwards or move down the track at high speed.

While the athletic activities may demand different responses from the body, the underlying physiology is similar. Sports physiology is concerned with the response of muscles. Other functions of the body change to support the demand for increased muscular activity. For example, the heart will beat faster in order to supply more blood to the muscles...