Dynamic Physical Fitness in Adolescence *

The term "physical fitness," like the term "fatigue," means many things to many people and before either can be profitably discussed it must be carefully defined. Physical fitness for most of the war duties implies that the heart, lungs, teeth, eyes, and all other parts of the body are organically sound and capable of, even though they may not be at present, working efficiently. It implies fitness for the performance of hard muscular work, including sudden bursts of energy as well as long-sustained efforts. It also implies various forms of specific fitness or skill: running, jumping, climbing, digging, throwing, and lifting. It is apparent that physical fitness has at least three main aspects: first, medical or static fitness which has to do with the soundness of various organs of the body. The degree of this fitness is determined by a careful medical examination and can be modified by various preventive and corrective medical procedures which a physician may advise. Second, functional or dynamic fitness, which has to do with the functional status of the body and its ability to do strenuous work. This can be measured by determining the physiological efficiency with which it does that work and the speed with which it recuperates. Third, that type of fitness which has to do with specific skills and which involves the development of special muscle coordinations and strengths so that various activities may be properly performed. It is with the second aspect of physical fitness, dynamic fitness, that these papers are concerned. The improvement of the medical or static fitness of our citizens and the development of their strength and skills are obviously very desirable, but those aspects of fitness are not discussed here. In all attempts to improve general fitness it is medical or static fitness which must be first considered; when one is sure that an individual is organically sound and, therefore, capable of becoming more efficient functionally, it is then proper to begin to