Introduction

Sustained physical exertion for the general purpose of maintaining or improving physical fitness or joint function.

Depending on the clinical needs and capabilities of patients, a physician may encourage regular exercise or may specifically prescribe therapeutic exercise. Therapeutic exercise is a defined program of regular exercise with specific objectives.

Exercise levels decline with age for many reasons, most commonly because chronic conditions and intercurrent illnesses in the elderly limit physical activity. About 35 to 45% of the elderly participate in minimal exercise. Only about 20 to 25% participate in regular exercise > 30 minutes 5 times/week. Women are less active than men. However, low income and low educational level are stronger predictors of inactivity than older age and female sex. Physical inactivity is the second leading cause (after tobacco use) of premature death in the USA.

Health Benefits

The benefits of exercise far exceed its risks, regardless of the presence of other risk factors: Regular exercise can reduce mortality rates even for smokers and obese persons. Indirect benefits include opportunities for social interaction, an enhanced sense of well-being, and possibly an improved quality of sleep. Direct benefits are myriad and include the following:

Improvement of physical and physiologic factors: Regular exercise can preserve skeletal muscle strength, aerobic capacity, and bone density, contributing to mobility and independence. Exercise is one of the few interventions that can restore physiologic capacity once it has been lost.

Skeletal muscle strength and power (rate of doing work) decline with age. These changes (an annual loss of 1 to 2% in strength and 3 to 4% in power between ages 65 and 85) are accompanied by sarcopenia (loss of muscle fibers, muscle mass, and motor units), which contributes to a loss of independence. All of these changes can be prevented, at least partially, or reversed by appropriate exercise.

Regular exercise also promotes a balanced energy state and reduces the risk of obesity. Regular exercise (> 30 minutes/day of moderate-intensity activity) increases success in initial and long-term weight loss, but weight loss usually requires reduced caloric intake as well.

Improvement of functional ability: Regular exercise reduces the risk of age-related decline in functional ability, and it appears to improve quality of life by improving physical functioning and enhancing psychologic well-being.

Prevention and treatment of disease: In the elderly, regular exercise increases insulin sensitivity and glucose tolerance, reduces resting systolic and diastolic blood pressure, normalizes blood lipid levels (including a reduction in circulating triglycerides and an increase in high-density lipoprotein cholesterol), and reduces visceral fat content. Thus, regular exercise can help prevent cardiovascular disease (eg, coronary artery disease, hypertension), diabetes, osteoporosis, obesity-related disorders, colon cancer, and psychiatric disorders (especially mood disorders such as depression). Regular exercise is also recommended as part of the treatment of these disorders and others (eg, pulmonary disorders). It is part of rehabilitation after a myocardial infarction or after surgery.

Endurance (aerobic) and muscle-strengthening exercises can reduce functional limitations in the elderly. The least fit persons improve the most, presumably because of a nonlinear relationship between physical fitness and functional ability. Improvements can be maintained by continued exercise.

Prevention of falls and fall-related injuries: Regular exercise can help prevent falls and fall-related injuries by improving several risk factors for falls related to poor mobility, including strength, balance, neuromuscular coordination, joint function, and endurance. Exercise provides an overall benefit, despite a modest increased risk of falls during the exercise. Regular exercise, especially a program that includes balance training, is recommended by the U.S. Preventive Services Task Force as a primary preventive measure against falls.

Reduction in mortality: Many cohort studies report that regularly active elderly persons have 20 to 50% lower mortality rates, despite a slight (but widely publicized) temporary increase in the risk of sudden death during exercise.

Health Risks

Musculoskeletal injury (eg, torn ligaments, pulled muscles) is the most common risk. Falls and fall-related injuries (eg, hip fractures) can occur during exercise. Physically active young and middle-aged persons probably have a slightly higher fracture rate than does the general population. Physically active adults appear to have an overall lower rate, although the risk of fractures increases rapidly with age. In addition, the risk of sudden death is temporarily increased during exercise, especially when the exercise is vigorous and the exerciser is sedentary and poorly conditioned.