8.10: Starting or Increasing Exercise

Clearly, elderly individuals who have been involved in vigorous physical activity throughout their lives benefit from such a lifestyle. Young people who adopt active lifestyles can expect to reap the same benefits when they become elderly. Furthermore, people of any age who have lived sedentary lives and begin to get exercise and those who have been getting only low or moderate amounts of exercise for many years and increase their exercise can improve their well-being. We will now examine outcomes in older people who begin vigorous exercise or substantially increase their level of physical activity.

Effects

Many effects on older people who begin or increase physical activity are listed in Table 8.2.

Circulatory System

The rise in maximum cardiac output is evident within a few days to weeks of initiating an exercise program. The more intense the exercise program, the sooner a significant increase in maximum cardiac output appears. This rise begins to be reversed within days of ending the exercise program. The final maximum cardiac output of those leaving an exercise program will be about the same as that which existed when the exercise program began. Altering blood lipoprotein levels requires a decrease in body fat along with the effects of the exercise.

Respiratory System

There is disagreement about whether increasing exercise increases respiratory volumes and speed of airflow, but long-term participation in exercise programs slows the decline in respiratory functioning. Therefore, in the long run elderly individuals who exercise will eventually have better respiratory system functioning than they will if they remain sedentary.

The respiratory system changes caused by a proper exercise program are of special importance to persons who have chronic obstructive pulmonary diseases (COPDs) such as chronic bronchitis and emphysema.

Nervous System

The mechanisms by which strenuous exercise increases strength in older people are different from those in younger people. At younger ages the increase in strength from training with heavy weights is caused almost exclusively by thickening of the muscle cells rather than alterations in the nervous system. Perhaps the change in mechanisms for increasing strength is a way the aging body partially compensates for a decreased ability of the muscle cells to adapt to lifting or moving heavy loads.

Muscle System

The gain in strength achieved by older individuals is proportionately the same as that which younger adults attain with the same type of exercise. For example, consider an older person who has had little exercise for many years and a younger adult who has had the same level of activity. The older person will not be as strong as the younger adult because the older adult has been losing strength for a longer period. If both individuals begin an exercise program designed to double the strength of an adult, both will end the program with twice the strength they had when they started. Of course, since the younger person was stronger at the start of the program, he or she will be the stronger person at the end. However, an older person who participates in such a program can become stronger than a younger adult who remains sedentary.

Older individuals whose exercise is not strenuous enough to cause an increase in strength still benefit because they at least have a slower decline in strength. Therefore, after long-term involvement in physical activity these individuals will be stronger than they would have been if they had remained sedentary. They will also have retained more total muscle mass. Keeping a high muscle mass helps the functioning of insulin.

Alterations in *VO₂max caused by increased exercise are similar in three ways to exercise-induced changes in strength. First, the increase in *VO₂max attained by an older person is proportionately the same as that achieved by a younger adult who starts with the same capability and participates in the same exercise program. Second, elderly people who increase their physical activity enough can develop values that are greater than those of much younger adults who remain sedentary. Third, elderly people whose increase in exercise is not enough to produce an increase in *VO₂max will still benefit because even small increases in physical activity slow the decline in *VO₂max. Therefore, these individuals will eventually have a greater *VO₂max than they would have had if they had remained sedentary.

There is an important difference between the effects of exercise on alterations in conditions such as blood lipoproteins, body composition, percent body fat, functioning of insulin, and strength and the effects on alterations in *VO₂max. Though vigorous activity is needed to effect substantial changes in the first five parameters, for very sedentary older people even low levels of easy activities such as walking can substantially increase *VO₂max. The resulting improvements can restore the ability of very sedentary elderly individuals with extremely low *VO₂max values to perform the ordinary activities of daily living.

All the exercise-induced alterations in the nervous and muscle systems just described combine to produce several other benefits in the elderly. These benefits include the perception that less effort is needed to perform demanding tasks; improved mood and sense of well-being; improved social interactions; and increased independence.

Skeletal System

Aging of the skeletal system raises the risk of sustaining fractures by causing demineralization of bones and reducing the ease of movement and range of motion of joints. Some forms of the joint disease called arthritis exaggerate these changes.

No one knows the best exercise program for slowing or reversing bone demineralization caused by aging or osteoporosis; different programs may be effective for different individuals. Also, different individuals can tolerate different amounts and types of exercise. The causes of these differences include physical condition, presence of diseases, lifestyle, and motivation.

The possible benefits of slowing bone demineralization and deterioration of joint functioning through a large increase in strenuous or vigorous physical activity must be weighed against the added risk of injury. Some more common problems include increased risk of fracture of the bones in the spinal column caused by lifting or holding heavy loads, increased risk of fracturing hip, leg, or arm bones by falling, traumatic injury to the bones, muscles, ligaments, and tendons in the lower legs from walking or running on hard surfaces or with improper footwear, and injury to the joints from excessive movements or forces, including impact forces.

Endocrine System

Exercise leading to a decrease in body fat significantly improves glucose tolerance and insulin sensitivity in elderly people who have a reduced glucose tolerance or non-insulin-dependent diabetes mellitus (NIDDM). Individuals who improve their glucose tolerance and insulin sensitivity have a substantially reduced risk of developing the complications associated with diabetes.

These beneficial effects of exercise begin to develop within days or even hours after a person increases the level of vigorous physical activity. Improvement increases as body fat decreases. However, the beneficial effects of the exercise begin to dwindle within a few days of ending involvement in the exercise program. Therefore, to sustain the benefits of exercise, a person with reduced glucose tolerance or NIDDM must engage in the exercise at least once every three days.

By contrast, individuals with type I (insulin-dependent) diabetes mellitus (IDDM) have very unstable blood sugar levels. Therefore, the amount of exercise they get must be carefully monitored and adjusted according to factors such as the severity of the disease, diet, and insulin treatments.

Other Effects

The effects of increasing exercise mentioned up to this point are related to specific body systems, but elderly people who increase their exercise seem to benefit in many other ways. These other benefits include helping to maintain normal body weight by improving nutrition and using more calories; increasing independence by generally slowing the onset of disability and physical limitations; and helping to enhance psychological health by improving mood and sense of well-being while reducing boredom, anxiety, and stress.

The physical and psychological effects of exercising also increase older individuals' ability to remain productive and economically self-sufficient. Their social situation is bolstered by the additional social interactions obtained through exercise programs and through an enhanced ability to participate in other activities in the community. Therefore, while increasing exercise has not been shown to lengthen life, it dramatically improves the quality of life for older individuals.