Exercise and the aging heart.

Studies of the effect of age on cardiac function during exercise are confounded by the increasing prevalence of disease and sedentary lifestyle that accompany aging and by the lack of techniques to clearly distinguish between the contribution of changes in central circulatory and peripheral factors to the age-related alterations in cardiovascular physiology. Although diastolic filling is delayed at rest, end diastolic volume is not compromised either at rest or during exercise. Exercise heart rate is invariably reported to decrease with increasing age, whereas stroke volume has been reported to be both increased and decreased in studies of different populations. Most investigators report an increase in end systolic volume and a diminished ejection fraction in older individuals as well. These changes are mediated, in part, by an age-associated diminished responsiveness to beta-adrenergic stimulation.