Physical Changes With Aging
Most age-related biologic functions peak before age 30 and gradually decline linearly thereafter (see table Selected Physiologic Age-Related Changes); the decline may be critical during stress, but it usually has little or no effect on daily activities. Therefore, disorders, rather than normal aging, are the primary cause of functional loss during old age.
In many cases, the declines that occur with aging may be due at least partly to lifestyle, behavior, diet, and environment and thus can be modified. For example, aerobic exercise can prevent or partially reverse a decline in maximal exercise capacity (oxygen consumption per unit time, or Vo2max), muscle strength, and glucose tolerance in healthy but sedentary older people.
Only about 10% of older adults participate in regular physical activity for > 30 minutes 5 times/week (a common recommendation). About 35 to 45% participate in minimal activity. Older adults tend to be less active than other age groups for many reasons, most commonly because disorders limit their physical activity.
The benefits of physical activity for older adults are many and far exceed its risks (eg, falls, torn ligaments, pulled muscles). Benefits include
Reduced mortality rates, even for smokers and the obese
Preservation of skeletal muscle strength, aerobic capacity, and bone density, contributing to greater mobility and independence
Reduced risk of obesity
Prevention and treatment of cardiovascular disorders (including rehabilitation after myocardial infarction), diabetes, osteoporosis, colon cancer, and psychiatric disorders (especially mood disorders)
Prevention of falls and fall-related injuries by improving muscle strength, balance, coordination, joint function, and endurance (1)
Improved functional ability
Opportunities for social interaction
Enhanced sense of well-being
Possibly improved sleep quality
Physical activity is one of the few interventions that can restore physiologic capacity after it has been lost.
Selected Physiologic Age-Related Changes
The unmodifiable effects of aging may be less dramatic than thought, and healthier, more vigorous aging may be possible for many people. Today, people > 65 are in better health than their ancestors and remain healthier longer.
Exercise is usually used to mean movement that generates aerobic debt and increased heart rate and for many people is an important behavior with many positive outcomes. However, simple physical activity (eg, walking, gardening) has many of the same benefits for older people, especially those > 70; thus, physical activity, without aerobic debt or cardioacceleration, is recommended, even for those with mobility limitations.
All older patients starting an exercise program should be screened (by interview or questionnaire) to identify those with chronic disorders and to determine appropriate activities; however, virtually anyone can begin brief periods of walking, increased to 30 minutes 5 times a week. Physical activity is inappropriate for only a few older people (eg, those with unstable medical conditions). Whether those with chronic disorders need a complete medical examination before starting an activity depends on the results of tests that have already been done and on clinical judgment. Some experts recommend such an examination, possibly with an exercise stress test, for patients who have ≥ 2 cardiac risk factors (eg, hypertension, obesity) and who plan on starting an activity more strenuous than walking.
Exercise programs that are more strenuous than walking may include any combination of 4 types of exercise: endurance, muscle strengthening, balance training (eg, tai chi), and flexibility. The combination of exercises recommended depends on the patient’s medical condition and fitness level. For example, a seated exercise program that uses cuff weights for strength training and repeated movements for endurance training may be useful for patients who have difficulty standing and walking. An aquatics exercise program may be suggested for patients with arthritis. Patients should be able to select activities they enjoy but should be encouraged to include all 4 types of exercise. Of all types of exercise, endurance exercises (eg, walking, cycling, dancing, swimming, low-impact aerobics) have the most well-documented health benefits for older adults.
Some patients, particularly those with a heart disorder (eg, angina, ≥ 2 myocardial infarctions), require medical supervision during exercise.
High-intensity muscle-strengthening programs are particularly appropriate for frail older patients with sarcopenia. For these patients, machines that use air pressure rather than weights are useful because the resistance can be set lower and changed in smaller increments. High-intensity programs are safe even for nursing home residents > 80 in whom strength and mobility can be substantially improved. However, these programs are time-consuming because participants usually require close supervision.
Doses of insulin and oral hypoglycemics in diabetics may need to be adjusted according to the amount of anticipated exercise to prevent hypoglycemia during exercise.
Doses of drugs that can cause orthostatic hypotension (eg, antidepressants, antihypertensives, hypnotics, anxiolytics, diuretics) may need to be lowered to avoid exacerbation of orthostasis by fluid loss during exercise. For patients taking such drugs, adequate fluid intake is essential during exercise.
Some sedative-hypnotics may reduce physical performance by reducing activity levels or by inhibiting muscles and nerves. These and other psychoactive drugs increase the risk of falls. Stopping such drugs or reducing their dose may be necessary to make exercise safe and to help patients adhere to their exercise regimen.
1. de Souto Barreto P, Rolland Y, Vellas B, et al: Association of long-term exercise training with risk of falls, fractures, hospitalizations, and mortality in older adults: a systematic review and meta-analysis. JAMA Intern Med.179(3):394-405, 2018. doi:10.1001/jamainternmed.2018.5406.
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