Exercise Physiology

The union of endocrinology and exercise physi­ ology has produced a need for increased under­ standing of one discipline by the other. This article is intended to facilitate that process by summariz­ ing the basic concepts, principles, and terminology of exercise physiology. In addition, problems spe­ cific to the union of endocrinology and exercise physiology will be discussed. The basic science of exercise physiology studies the physiologic adaptations and control mechanisms which occur during acute exercise and as a result of chronic exercise. This study is dependent on the integration of neural physiology, muscle phys­ iology, cardiovascular physiology, respiratory physi­ ology, environmental physiology, metabolism, and endocrinology. The application of the basic science is currently divided into two broad areas: ergo­ nomics and clinical medicine. Ergonomics is the study of human performance under varying conditions extending from the work site to the athletic field. Two major concerns at the work site are work efficiency specific to the task and working conditions, and injury prevention and management. In athletics, basic physiology is ap­ plied to optimize training techniques, fuel efficiency, and ergogenic aids to find the limits of and to improve athletic performance. Clinical medicine involves the application of exer­ cise to health, disease, and aging. In addition to defining the role of exercise programs in health states such as pregnancy and normal aging, the application of exercise programs in the prevention and rehabilitation of various cardiovascular, respi­ ratory, and metabolic diseases is studied. Endocrinology and exercise physiology have re­ cently been integrated to study hormone changes and hormonal control mechanisms during acute exercise and as a result of chronic exercise. The scope of this union includes at least (1) elucidation of sex hormone changes and menstrual function in young athletic women; (2) consideration of the association of β-endorphin response during exer­ cise and mood states; and (3) evaluation of the role of exercise in the control of diabetes. These ques­ tions can best be answered in the presence of a common knowledge base. Standard terminology for exercise physiology has been summarized by the American College of Sports Medicine. In addition, exercise must always be described in terms of mode, frequency, duration, and intensity. The mode, frequency, and duration are somewhat self-explanatory. Intensity can be expressed in relative or absolute terms. Since there is wide individual variation, relative intensity (which is a percentage of maximal capac­ ity) is often more meaningful than absolute inten­ sity.