The deleterious effects of inactivity on the functional capacities of several organ systems in the human are effectively documented and described by Kottke elsewhere in this issue (p 825). For many years physiologists have studied the effects of exercise on the cardiovascular and neuromuscular systems, so that we are now well aware of many specific physiologic effects of mild and strenuous physical activity on cardiac function, circulation, and muscular strength, and thus have the basic knowledge useful in the management of many patients. However, only relatively recently have physiologists become actively concerned in evaluating physiologic effects of bed rest, immobilization, and varying states of inactivity. The knowledge obtained from these and future studies should be of vital interest to physicians and others concerned with the guidance and regulation of the activities of patients, aging citizens, astronauts, and space travelers, as well as average persons.
Our contemporary civilization tends to foster