A common belief among the lay public, as well as among many health-care professionals, is that much of the disease and loss of function that commonly accompanies aging is inevitable and a result of the “aging process” itself. However, it has become clear that much of the physical decline and reduced physiological reserve previously blamed on aging is, in fact, caused by the complex interactions of true genetically determined aging, disease (often subtle or subclinical), disuse, and environmental exposure.
The myriad of possible interrelationships among these factors makes it difficult to ascribe specific causality for the loss of physical vigor or function. Thus, for example, preconceived societal notions about aging may predispose to greatly reduced expectations with regard to physical as well as mental performance. Such preconceptions may promote inactivity and disuse in women at an even earlier age than in men. With years of ensuing inactivity, disuse not only exaggerates and enhances any true age-related loss of endurance, strength, and flexibility, leading to further inactivity and disuse, but may also exacerbate previously subtle or subclinical diseases such as intra-abdominal obesity, glucose intolerance, osteopenia, hypertension, dyslipidemia, and coronary artery disease. These physiological disorders, the drugs used in their treatments, and the associated functional impairments and disability can, in turn, further limit activity and continue the vicious downhill spiral.
Physical activity level (and measured fitness) appears to be inversely related to the risk of mortality and is associated with a greater average life span (approximately 2 years in human studies). An inverse dose–response relationship has also been noted between physical activity and the risk of developing many important diseases (cardiovascular disease [CVD], stroke, hypertension, type 2 diabetes, osteoporosis, obesity, colon and breast cancer, anxiety, and depression). Many of these reports included older adults. Despite the clear advantages to physical activity, less than 40% of persons 65 years and older meet the CDC recommendations for activity, and this percentage falls significantly further in older age groups.
This chapter reviews the physiological effects of aging and exercise training on the most common measures of physical fitness: (1) endurance or maximal aerobic exercise capacity, (2) skeletal muscle strength and power, and (3) body composition. Next, it investigates the theoretical relationship between fitness and functional status, reviewing the available, albeit somewhat limited, data on the effects of increased activity on functional performance. The chapter then reviews the effects of aging and activity on disorders commonly observed in geriatric patients. Last, the risks associated with exercising are discussed and some suggestions are made with respect to prescribing an exercise program for older individuals.
While we and others commonly discuss health benefits of “exercise training,” it is now abundantly clear that many benefits can be accrued simply through a more active (nonsedentary) lifestyle in the absence of formal “exercise training.” This concept may be especially helpful in trying to encourage older individuals who feel unable or unwilling to engage in formal exercise ...