ABSTRACT
As we turn from cellular and subcellular events to changes in gross form and function, it becomes much more difficult to distinguish true aging from the superimposed effects of environment and disease. The available database refers largely to the sedentary and overfed population of North America, and in many instances it becomes necessary to report the actual capacity and power of physiological systems, without forming a judgement as to whether the observed deterioration of performance is a necessary and inevitable accompaniment of aging.
