Although exercise is a major component of a healthy lifestyle, many questions have been raised about how best to benefi t from it. For example, how hard and for how long should one exercise to gain these benefi ts? What does being in “good shape” actually mean, and can this be quantifi ed and studied? Related to exercise pharmacology, questions include: what effects does exercise have on individuals who are taking medications, and what effects do drugs have on those who exercise? In order to start to answer these exercise pharmacology-related questions, it is important to understand the basics of exercise physiology, particularly the physiological changes observed during exercise. This next section will cover some of these basics related to the cardiovascular, metabolic, and muscular systems. This chapter will also cover exercise prescription for health, the need for and complexity of exercise pharmacology research, and the methods of testing for drugs that may enhance or affect performance.