Formulation of the Exercise Prescription

The exercise prescription may include any combination of four types of therapeutic exercise--endurance exercises, muscle-strengthening exercises, balance training exercises, and flexibility exercises. The activities must be appropriate for a patient's level of fitness and medical condition. For example, patients with emphysema typically have low levels of fitness. Treadmill exercise may need to be performed at a very slow speed to accommodate marked deconditioning. Rehabilitation after a broken ankle may emphasize flexibility exercises to restore range of motion and muscle-strengthening exercises to address muscle wasting at the ankle joint due to immobilization. Patients with difficulty standing and walking can participate in seated exercise programs that use cuff weights for strength training and repeated movements for endurance training. Patients with arthritis may prefer an aquatics exercise program.

To maximize adherence, the physician should allow patients to select the activities they enjoy; ideally, the activities selected by the patient should include endurance, strength, balance, and flexibility exercises as prescribed by the physician. Some patients want to do the same activity every day; others want variety. Many patients prefer to exercise alone; some prefer exercise classes. Some patients require medical supervision during exercise (see Table 31-2).

The Centers for Disease Control and Prevention recommends that all adults participate in > 30 minutes of moderate-intensity physical activity > 5 days/week. Patients do not have to be active for 30 minutes at a time but can accumulate 30 minutes over 24 hours. As little as 10 minutes of exercise has health benefits, and three 10-minute bouts of activity have the same fitness effects as one 30-minute bout. Some elderly patients (eg, those with osteoarthritis) may prefer activity in short bouts.

The elderly can meet the recommended activity goal by integrating activity into daily life (eg, walking to the store rather than driving). The U.S. Preventive Services Task Force recommends that health care practitioners counsel all patients on how to incorporate exercise into their daily routines (see Table 31-3). Some elderly patients can more easily adhere to this type of activity plan than to a formal exercise program.

Exercise need not be high intensity to have health benefits. Moderate-intensity activity (see Table 31-4) for only 30 minutes/day produces most of the health benefits of regular exercise. For the weak elderly, the usual moderate-intensity activities may be too strenuous. Therefore, activities that provide moderate intensity should be selected relative to fitness level, based on target heart rate and rating of perceived exertion during activity.

Exercises should be started at a low intensity for a short time, then gradually increased to the recommended intensity level. A program may begin by alternating 2 to 3 minutes of activity with 2 to 3 minutes of rest over 15 minutes. In deconditioned patients, even low-intensity activity can increase fitness.

Patients whose exercise program is interrupted for more than a few weeks (eg, by illness) should resume exercising at about half the intensity level. Then they can gradually increase to previous levels. Prolonged inactivity, especially bed rest, is not usually advised during recovery from illness. Each day of strict bed rest causes an incremental loss of muscle mass of about 1.5% and substantial losses in muscular performance and in cardiorespiratory fitness.

Endurance Exercises

Of all types of exercise, endurance exercises (eg, walking, cycling, dancing, swimming, low-impact aerobics) provide the most well-documented health benefits for the elderly.

Walking is the most common exercise among the elderly in the USA (about 50% of the elderly walk for exercise) and is the most commonly recommended clinically. In a recent study, the mortality rate was reduced 50% in people who walked an average of > 3.2 km/day (> 2 miles/day). Walking also reduces the risk of new heart disease and of falls. Jogging is generally inappropriate for elderly persons not already accustomed to it.

During endurance exercise, level of exercise correlates with risk of injury and should be monitored. The target heart rate method of estimating exercise intensity is most useful when maximal heart rate has been determined by an exercise stress test. Otherwise, the rating of perceived exertion method is usually better and is necessary in patients who have atrial fibrillation or frequent ectopic beats or who are being treated with drugs or devices that influence or control heart rate (eg, -blockers, pacemakers).

The target heart rate method: Patients can monitor their heart rate during exercise by taking their pulse or by using an exercise heart rate monitor. Moderate-intensity endurance exercise is defined as exercise that produces 60 to 79% of maximal heart rate. For example, elderly patients with a maximal heart rate of 150 beats/minute have a target heart rate of about 90 to 120 beats/minute during moderate-intensity activity.

An exercise stress test can determine the maximal heart rate and the target heart rate range. For patients who have not had a recent exercise stress test, maximal heart rate can be estimated using the formula "220 minus age." However, this formula is slightly conservative. For 80-year-old patients, the average maximal heart rate is between 140 and 150 beats/minute.

Patients whose heart rate is below the target range (see Table 31-5) while performing activities of 5 to 6 metabolic equivalents achieve most of the health benefits of activity and do not need to increase intensity level. However, if safe, an increase in intensity level to increase heart rate into the target range can increase health benefits.

Rating of perceived exertion method: Perception of exertion appears to be a good way to monitor intensity. The most commonly used scale is the Borg scale, on which activity is rated from 6 (extremely light) to 19 (extremely hard); moderate activity is rated 11 to 13. Actual intensity is linearly related to steady-state exercise heart rate, but not to perceived intensity. The Borg scale helps patients "calibrate" perceived intensity to actual intensity (see Table 31-6), often with the help of a fitness instructor.

Muscle-Strengthening Exercises

Many experts recommend that the elderly perform muscle-strengthening exercises at least 2 days/week. Normally, the same muscle group is not exercised more often than every other day. Strength training can increase bone density as well as improve muscle mass, strength, balance, and overall level of physical activity.

High-intensity programs can greatly increase strength. These programs use weight machines (eg, at gyms and other fitness centers), which are appropriate for healthy elderly patients. Resistance is set at 60 to 80% of the one-repetition maximum (ie, the maximal weight the patient can lift once). Typically, elderly patients perform two sets of 10 repetitions on 8 to 10 machines. Gains in strength can range from 30 to 150% during at least the first year of exercise. Muscle hypertrophy can also occur.

High-intensity programs are particularly appropriate for frail or near-frail elderly patients with sarcopenia. For these patients, machines that use air pressure rather than weights to provide resistance are more useful because the resistance can be set lower and changed in smaller increments. High-intensity programs are safe even for nursing home residents > 80 years old, for whom strength and mobility can be substantially improved. However, these programs are time-consuming because participants usually require close supervision.

Moderate-intensity programs maintain strength, or increase it 10 to 20% over several months and then maintain it. These programs include cuff weight exercises; calisthenics, which use body weight for resistance; and exercises using various thicknesses of elastic tubing for resistance. In cuff weight exercises, weighted cuffs are strapped to ankles or wrists or are held. They do not require expensive equipment, can be performed at home, and are especially useful in weak elderly patients. The weight can be adjusted in 0.227-kg (1/2-lb) increments by removing or adding small weight sacks. "Exercise: A Guide from the National Institute on Aging" (Publication No. NIH 98-4258) describes a cuff weight program.

Balance Training Exercises

Balance training exercises are indicated for elderly patients at increased risk of falls. Properly designed exercise programs can reduce the risk of falls (by about 10 to 15% in one meta-analysis), but those that include balance training appear most effective.

Tai chi (a variety of exercises involving sequences of movements originally used in the martial arts) is one type of program for improving balance. Home-based balance training exercise programs are also available.

Usually, balance training exercises are graduated. Patients begin with the simplest exercises and advance as appropriate. For example, level 1 = walking while holding onto a table; level 2 = walking with arms outstretched and ready to grab the table if balance is lost; level 3 = walking with arms crossed at the chest; and level 4 = walking with arms crossed at the chest and extra weight in the hands. Balance training exercises do not count toward the recommended 30 minutes/day of moderate-intensity activity.

Flexibility Exercises

Flexibility exercises increase range of motion. Some elderly patients report that flexibility exercises make their bodies feel better. These exercises are commonly recommended to reduce injury risk; however, this benefit has not been studied in the elderly.

A wide variety of stretching exercises are used. Stretching is recommended after endurance and muscle-strengthening exercises, when muscles are warm. A stretch is held for 10 to 30 seconds, 3 to 5 times per session. It is performed slowly, without jerking or bouncing.

Flexibility exercises are generally low intensity. They do not count toward the recommended 30 minutes/day of moderate-intensity activity.