Aging is associated with a progressive decrement in various components of physical work capacity, including aerobic power and capacity, muscular strength and endurance, and the tolerance of thermal stress. A part of the functional loss can be countered by regular physical activity, control of body mass, and avoidance of cigarette smoking. Nevertheless, athletes who continue to train regularly still show a substantial aging of both physiological function and competitive performance, reflecting a deterioration of cardiac pump function, a decrease of muscle strength, and a progressive impairment of heat tolerance. These various changes are of concern to the occupational physician, because of the rising average age of the labor force. In theory, an over-taxing of the heart and skeletal muscles might be thought to lead to a decrease of productivity, manifestations of worker fatigue such as absenteeism, accidents, and industrial disputes, and an increased susceptibility to musculoskeletal injuries, heart attacks, and strokes. However, in practice, the productivity, health, and safety of the older worker pose relatively few problems. Reasons for this paradox are discussed, and it is stressed that in general there is no longer need to push workers to their physical limits because of automation-related changes in methods of production.