Researchers have spent a considerable amount of time searching for a single test that would best measure physical fitness. As early as 1884, an Italian by the name of Mosso experimented with the effects of exercising a muscle on an ergometer. He was one of the first physiologists to hypothesize that muscular efficiency was dependent upon circulatory factors. Following Mosso's work, many experiments have been conducted to show certain cardiovascular factors to be related to good physical condition.
Recent studies suggest that physical inactivity may be related to the increasing prominence of ischemic vascular disease, the most significant form being coronary heart disease (CHD). Of particular note is the study of transport workers by Morris and associates,25 who found a higher incidence of CHD in the less active drivers than in conductors; also, less active postal workers were found to have a much higher incidence of CHD than the postmen.
Fox and Skinner,18 in summarizing a large number of studies which compared sedentary and active individuals, found a definite trend favoring a lower incidence of CHD among the more active. As a result of these recent studies, much emphasis has been placed upon getting people to exercise and devising new instruments for the evaluation of cardiorespiratory endurance.
In order to achieve some basic understanding of the principles underlying the construction of cardiovascular tests, it seems wise at this point to review briefly the physiological characteristics found to be most generally associated with a highly trained body.
Minute volume. The output of the heart per beat is referred to as the stroke volume, and the output per minute as the minute volume. The stroke volume multiplied by the pulse rate equals the minute volume, and the minute volume divided by the pulse rate equals the stroke volume. It is a common belief that trained athletes usually have a greater stroke volume at rest than do less well-conditioned persons. This development