Exercise and heart failure in the elderly.

In this review, we will examine the physiological responses to exercise in elderly populations (age > 65 years) with and without evidence of heart failure. Aging per se in both men and women is associated with a ~40% lower maximum oxygen consumption in sedentary subjects. In trained individuals, this value is 25-32% lower. A smaller SV accounts for nearly 50% of these age-related differences, and the remainder is explained by a lower maximal HR and reduced oxygen extraction. Exercise training is also associated with an increase in the arteriovenous O(2) difference in previously sedentary elderly men and women, which probably contributes to the overall beneficial effect of training in the elderly. However, during vigorous exercise (125 W), the cardiac output in the elderly is dependent upon an age-related increase in end-diastolic volume and stroke volume, which "compensates" partially for the age-related decrease in heart rate. Hence, in elderly individuals, the stroke volume during exercise depends upon diastolic filling. The changes that occur in the heart are also associated with an overall reduction in efferent sympathetic nerve activity. Despite this decline, the metaboreflex initiated by receptors in exercising muscles remains the main determinant of sympathetic activation (to maintain blood pressure) during exercise in the elderly. It is recognized that aging is associated with the development of heart failure, particularly in women in whom its prevalence increases >twofold from age 65-69 (6.6%) to age 85 years (14%). Almost half the people presenting with heart failure appear to have normal left ventricular systolic function, a phenomenon that is more common in women. Exercise training in elderly people with and without heart failure appears to have a beneficial effect in terms of enhancing the quality of life and functional capacity. Mortality benefit in the latter has not been established with certainty.