As people age, the heart tends to enlarge slightly, developing thicker walls and slightly larger chambers. The increase in size is mainly due to an increase in the size of individual heart muscle cells. The age-related stiffening of the heart walls causes the left ventricle to not fill as well and can sometimes lead to heart failure (called diastolic heart failure or heart failure with preserved ejection fraction), especially in older people with other diseases such as high blood pressure, obesity, and diabetes.
During rest, the older heart functions in almost the same way as a younger heart, except the heart rate (number of times the heart beats within a minute) is slightly lower. Also, during exercise, older people's heart rate does not increase as much as in younger people.
The walls of the arteries and arterioles become thicker, and the space within the arteries expands slightly. Elastic tissue within the walls of the arteries and arterioles is lost. Together, these changes make the vessels stiffer and less resilient. Since the arteries and arterioles are less elastic, blood pressure cannot adjust quickly when people stand, and older people are at risk for dizziness or in some cases fainting when they stand up suddenly.
Because arteries and arterioles become less elastic as people age, they cannot relax as quickly during the rhythmic pumping of the heart. As a result, blood pressure increases more when the heart contracts (during systole)—sometimes above normal—than it does in younger people. Abnormally high blood pressure during systole with normal blood pressure during diastole is very common among older people. This disorder is called isolated systolic hypertension.
Many of the effects of aging on the heart and blood vessels can be reduced by regular exercise. Exercise helps people maintain cardiovascular fitness as well as muscular fitness as they age. Exercise is beneficial regardless of the age at which it is started.