The age-related decrease in cardiorespiratory fitness in the elderly has been attributed to the aging process and to reduced activity levels. The cardiorespiratory response to exercise across the ages (19-102y) was examined in order to describe the age-related rate of decline of cardiovascular function, study the effect of an exercise training program on this decline and discover whether the control mechanisms of the integrated response to exercise are affected by aging.;Both men and women showed a curvilinear decrease in self-selected walking speed with age (19-102y). In the older age range ({dollar}\u3e{dollar}60y), minimal oxygen consumption (VO{dollar}\sb2{dollar}max) was predicted best by an equation of age, weight and sex, and not by the self-selected walking speed.;In a longitudinal study of exercise training and detraining, an age-related decline in VO{dollar}\sb2{dollar}max, ventilatory threshold and oxygen consumption at a heart rate of 125 beats {dollar}\cdot{dollar} min{dollar}\sp{lcub}-1{rcub}{dollar} was found for sedentary and active older (60-70y) men. Exercise training for 5 years did not slow the rate of decline of these variables. The men who trained, however, had significantly higher VO{dollar}\sb2{dollar}max levels than the sedentary control group and the men who stopped training.;Age-related changes in cardiorespiratory kinetics were studied in a group of young (21-28y) and elderly (62-73y) women, using breath-by-breath procedures. Tests were performed on the treadmill (ramp-like work rate functions) and cycle ergometer (ramp, square-wave & sine-wave work rate functions). The oxygen consumption (VO{dollar}\sb2{dollar}) response to ramp tests showed a longer mean response time (MRT) in the elderly ({dollar}\u3e{dollar}60y), but only during cycle ergometry. Square-wave tests showed that the time delay (T{dollar}\sb{lcub}\rm D{rcub}{dollar}) and time constant (tau) was longer for VO{dollar}\sb2{dollar} and heart rate responses, and the tau was longer for ventilation (V{dollar}\sb{lcub}\rm E{rcub}{dollar}) response. The carbon dioxide production (VCO{dollar}\sb2{dollar}) response did not show a significant longer MRT with age. The tight coupling of the V{dollar}\sb{lcub}\rm E{rcub}{dollar} and VCO{dollar}\sb2{dollar} responses observed in the young appears to be loosened with age. The cardiorespiratory control mechanisms responded in a first-order fashion regardless of age. The control system kinetics, however, were significantly slower in the elderly during all three work rate forcing tests
