Effects of Aging

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.

During rest, the older heart functions in almost the same way as a younger heart except the heart rate is slightly lower. However, during exercise, the older heart cannot increase the amount of blood pumped out as much as a younger heart can.

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.

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 (see Section 3, Chapter 22).

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. Also, exercise is beneficial regardless of the age at which it is started.