VALUE OF LONGITUDINAL STUDIES OF EXERCISE FITNESS TESTS

Abstract

THE TERM "longitudinal study" implies observation or experimentation over a considerable period of time. Just what this period of time will be depends upon the phenomenon and the organism being studied. If, for example, one is interested in the growth rates of long bones in mice, a few months is sufficient. In human beings fifteen to twenty years would not be out of line since, wanting to know how the individual arrives at his ultimate length, one must measure him periodically during his entire growing period. To be worthwhile, therefore, the longitudinal study must be designed to answer questions which cross-sectional data cannot answer. In order to discuss intelligently the value of longitudinal studies of exercise fitness tests, one must at the outset define what the objectives are in such studies. Consider the following questions: 1. What are the effects of growth, of sex, and of aging on the fitness of the individual? 2. In the absence of conditioning programs, is the level of fitness of an individual a rapidly-changing measurement, or does it demonstrate relative constancy? 3. When conditioning programs are considered, what is the effect of their onset, duration, and cessation on the individual level of fitness? 4. What are the immediate and longterm results of illness on the individual level of fitness? 5. What, if anything, can one say about the effect of fitness levels on the longevity of the individual? The answers to these and related questions are the principle goals of longitudinal fitness studies. How successfully, then, have such longitudinal studies been carried out?