The process of aging is a continuum progressing throughout an individual’s life, which results in alterations in cardiovascular and pulmonary physiology. The effects of aging on the cardiovascular and respiratory system are numerous, diverse, complex, and often interactive. There is considerable variability in what is defined as “normal” function with age and it can sometimes be difficult to distinguish it from age-related comorbidities.1 Changes with age occur in everyone, but not necessarily at the same rate, so physiologic aging in any given individual may occur more rapidly or more slowly than the chronologic age.2 Many diseases of the cardiovascular and pulmonary systems occur heterogeneously in increasing frequency as age increases. As a result, impaired function and performance is not only the consequence of advanced age, but also the result of cardiovascular, respiratory, and other disease processes, making it difficult to discriminate between disease-related and age-related changes.2 In all individuals, physical activity impacts cardiovascular structure and function, and conversely, cardiovascular structure and function profoundly impacts the ability to participate in physical activity. Physical therapists play a crucial role in providing primary, secondary, and tertiary prevention and rehabilitation as part of the healthcare team and therefore must be proficient at assessing the health of the cardiovascular and pulmonary system.
AGE-RELATED CHANGES OF THE CARDIOVASCULAR SYSTEM
It is difficult to differentiate between aging and pathological changes in the circulatory system because the distinction is not completely clear.3 Consistent with the impact of aging on collagen throughout the body, changes in collagen and elastin tissues in the heart and arteries result in increased thickness and decreased elasticity of the vessels.3,4 Compared to vessels from healthy younger individuals, arteries from older individuals are characterized by increased radical oxygen species (ROS) content, inflammatory changes, decreased nitric oxide (NO) availability, and endothelial dysfunction.4,5 Changes in humoral and endothelial regulation of vascular smooth muscle tone further impact the aging vasculature.4,6,7 The endothelium plays an active role in maintaining vascular homeostasis by balancing vasodilation and vasoconstriction, inflammation, thrombosis, and oxidation by secretion of various vasoactive molecules. The clinical impact of age-related endothelial dysfunction is a reduction in the regulatory capacity of blood flow and promotion of atherosclerosis and thrombosis.7
Changes in heart structure include a thickening of the left ventricular wall and increase in fatty tissues in the outer layer of the heart muscle. There is an accumulation of lipofuscin in the myocardium and thickening and sclerosis of the valve flaps of the heart causing them to be less efficient and possibly result in heart murmurs.3,4 With age, cardiac myocytes tend to hypertrophy and decrease in number, causing a change in ventricular wall thickness. The left ventricle becomes stiffer and therefore its compliance decreases.4,8 Diastolic function undergoes significant age-related changes, with a reduction in early diastolic filling compensated by increased end-diastolic filling....