THE CARDIOPULMONARY RESPONSE TO INCREMENTAL EXERCISE TEST - THE EFFECT OF AGING

The aims of the present study were to define the respective roles of t he cardiac and respiratory response to exercise as determinants of the age-related physiological decrease in exercise performance, and to as sess the relationship between aging and interindividual variability in the response to effort. We studied 91 normal subjects recruited in th ree age-groups: Group A (42 children, aged 10+/-2 years); Group B (29 young adults, aged 27+/-5 years); Group C (20 elderly,aged 74+/-9 year s). All the subjects underwent an incremental cycle ergometer exercise test with ct work load increase of 15 W every 2 minutes in groups A a nd C, and 25 W every 2 minutes in group B, until they achieved 80% of the predicted maximal heart rate. Ventilatory equivalent changes durin g exercise were significantly lower in group A than in the other two g roups, and in group B compared to group C. Exercise-induced changes in oxygen pulse were significantly higher in group A, but no difference was found between groups B and C. Thus, gas-exchange function and over all exercise performance decrease with advancing age, whereas cardiova scular performance is well maintained in normal elderly subjects. Disc riminant analysis showed that the exercise response conformed to the g roup-specific model in 74% and 79% of subjects in groups A and B, but only in 50% of the group C subjects; 5% and 45% of the elderly subject s were functionally classified in groups A and B, respectively. On the basis of these data, it may be concluded that aging accounts for a dr amatic increase in interindividual variability in adaptation to physic al effort, and that the inverse relationship between age and exercise performance is mainly related to the declining efficacy of the respira tory response to effort with age.