Current Geriatric Diagnosis & Treatment, 1st Edition

Section IV - Special Situations

42. Exercise

Stephanie Studenski MD, MPH

General Considerations

Although physical exercise has clear benefit to health and function, most older adults do not engage in any regular exercise activity. The challenge for the clinician is to promote exercise that is appropriate and feasible for the individual needs of the patient.

  1. TYPES OF EXERCISE & EXERCISE SETTINGS

Exercise can promote cardiopulmonary fitness, musculoskeletal power, balance, flexibility, and a general increase in capacity to expend metabolic energy. All types of exercise require a minimum intensity, frequency, and duration to achieve gain by inducing moderate physiological stress. Thus, exercise must include a plan for progression of duration and intensity over time. Exercise can be performed in the community, within the health care system, or at home. It can be self-managed or supervised, in groups or one on one. It can involve much or little equipment and cost.

  1. FITNESS LEVELS IN OLDER ADULTS

The exercise capacity and needs of older adults depend on their initial health and functional status and history of physical activity and exercise. Many older adults, especially the young-old (< 75), are in good health and have no functional limitations. These healthy elders include both usual healthy elders with no symptoms and fit elders. The usual can be differentiated from the fit by their capacity to perform demanding physical work or exercise. For healthy elders, standard exercise recommendations and precautions are appropriate. Some older adults who are independent in activities of daily living (ADLs) have subclinical disability, demonstrated by reduced physical performance. These persons require some adaptations to the exercise program. Those with frank disability benefit from therapeutic exercise for recovery of function. If the change in functional status is recent, exercise is offered as a part of a rehabilitation program. If the disability is chronic, exercise is more often part of a self-care program. Older adults with conditions involving the heart, lungs, bones, and joints or other organ systems need exercise targeted at certain physiological and functional parameters and require activity modifications for the condition.

Prior experience, knowledge, and beliefs about exercise will influence attitudes and expectations. Individuals who have personally experienced improved physical function with exercise in the past may be more receptive, whereas those who have had no experience or who have had prior injury with exercise may be less interested.

  1. TYPES OF GOALS FOR EXERCISE

Exercise can be preventive or therapeutic. Preventive goals for exercise aim to reduce adverse events in the future. In healthy adults, exercise can be a form of primary prevention, delaying disability and disease. Exercise in persons with subclinical disability or disease is a form of secondary prevention, like the treatment of hypertension, in which a detectable abnormality (high blood pressure, reduced physical performance, decreased bone density) is treated before it causes overt disease and disability (Table 42-1). Exercise for tertiary prevention has the goal of reducing recurrence or complications. Therapeutic exercise has immediate goals to improve symptoms and functions.

General Guidelines for Exercise

The health care provider should be able to assess medical safety for exercise and recommend medically indicated exercise modifications. The provider should also be able to give the independent older adult key recommendations for safe unsupervised exercise and should be involved in improving patient adherence to exercise programs.

  1. MEDICAL EVALUATION

Even though a medical evaluation is recommended before exercise for nearly all older adults, there are no clear guidelines for the medical assessment of exercise safety. Most guidelines tend to focus on cardiac screening and contraindications. Many other conditions also require specific exercise modification (Table 42-2).

There are long-standing misconceptions about the need for bed rest. Absolute bed rest is almost never a good thing; almost everyone benefits from some degree of physical activity. The very few contraindications to physical activity include recent myocardial infarction, unstable angina or uncompensated congestive heart failure, critical aortic stenosis, and significant abdominal aortic aneurysm. Some acute conditions such as major bone fracture, nonhealing lesion on a weight-bearing

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extremity, or febrile illness transiently limit activity. Those who are recovering from acute illness benefit from early mobilization (see Chapter 7: Hospital Care).

Table 42-1. Benefits of physical activity & exercise for older patients with chronic health conditions.

Condition

Benefits

Obesity

Reduces total abdominal adiposity

Diabetes mellitus type 2

Increases insulin sensitivity and glucose tolerance

Atherosclerosis

Increases luminal diameter of coronary arteries

Hypertension

Reduces resting blood pressure

Vascular disease

Increases resting and exercise stroke volumes and lowers resting and exercising heart rates

Cardiovascular disease: coronary diseases, congestive heart failure

Lowers risk of death after myocardial infarction; improves endothelial function and skeletal muscle aerobic metabolism and reduces afterload

Cerebrovascular disease

Reduces risk of total and ischemic stroke in women

Peripheral vascular disease

Increases maximal treadmill walking distance

Chronic obstructive pulmonary disease

Improves dyspnea

Obstructive sleep apnea

Weight loss

Sarcopenia

Resistance training improves muscle strength and size and improves mobility

Physical frailty

Postpones disability

Osteopenia/osteoporosis

Delays the decrease of bone mineral density

Low back pain

Improves performance of daily activities

Alzheimer's disease

Women with higher levels of physical activity are less likely to develop cognitive decline

Recovery from surgery, immobilization, debilitating illness

Decreases morbidity, morality, rehospitalization; improves quality of life, depression scores, and physical functioning

Depression

Improves symptoms of depression and anxiety

From Chakravarthy MV et al: An obligation for primary care physicians to prescribe physical activity to sedentary patients to reduce the risk of chronic health conditions. Mayo Clin Proc 2002;77:170. Used with permission.

Table 42-2. Modifications of exercise prescription for selected conditions.

Condition

Modification

Degenerative joint disease

Non-weight-bearing activities: stationary cycling, water exercises, chair exercises; low resistance-low repetition strength training

Coronary artery disease

Symptom-limited activities: moderate endurance activities (eg, walking, cycling); more vigorous activities at physician's discretion: lower resistance, higher repetition strength training

Diabetes mellitus

Daily, moderate endurance activities; low resistance, higher repetition strength training; flexibility exercises

Dizziness, ataxia

Chair exercises, low-resistance and low-repetition strength training; moderate flexibility activities with minimal movement from supine or prone to standing positions

Back syndrome

Moderate endurance activities and flexibility exercises; low-resistance, low-repetition strength training; modified abdominal strengthening activities; water activities

Osteoporosis

Weight-bearing activities with intermittent bouts of activity spaced throughout the day; low-resistance, low-repetition strength training and chair-level flexibility activities

Chronic obstructive lung disease

Moderate endurance activities using interval or intermittent approach; low-resistance, low-repetition strength training; modified flexibility and stretching exercises

Orthostatic hypotension

Minimize movements from standing to supine and supine to standing; sustained moderate endurance activities with short rest intervals

Hypertension

Dynamic large-muscle endurance activities; minimize isometric work and focus on low-resistance, low-repetition isotonic strength training

From American College of Sports Medicine: ACSM position stand on exercise and physical activity for older adults. Med Sci Sports Exer 1998;30:992. Used with permission.

Some medical conditions must be identified to modify the exercise program, to implement special safety procedures, or to prepare to adapt therapy to the condition itself. Most commonly, the screening focuses on risk of major cardiac events during exercise such as silent ischemia and exercise-induced arrhythmias. This is a controversial area in the literature. Cardiac screening recommendations are not consistent among official organizations. Exercise stress testing is expensive, is difficult to perform for many older adults, and uncovers a huge reservoir of silent cardiac disease of unclear clinical significance. Many older adults do not plan to undertake a vigorous exercise program, and moderate activity may be associated with negligible accumulated cardiac risk because there are also cardiac risk reductions associated with moderate exercise. Ideally, exercise should occur in a monitored environment after standard cardiac evaluation for persons at higher risk for cardiac events during exercise. This category includes persons with myocardial infarction within 6 mo, angina, symptoms or signs of congestive heart failure, resting systolic blood pressure > 200 mm Hg or resting diastolic blood pressure > 110 mm Hg, chest pain or shortness of breath during observed exercise, such as climbing a flight of stairs or cycling in the air while lying on the exam table, or a resting electrocardiogram with new Q waves, ST-segment depression, or T-wave inversions. Systolic blood pressure that drops with exercise is also a danger sign. There is no consensus about how to evaluate cardiac risk of exercise in asymptomatic persons with risk factors such as old myocardial infarction, other vascular diseases, pulmonary conditions, diabetes, hyperlipidemia, smoking, and hypertension. For individuals who do not have these risk factors, the provider may consider 2 options. Cardiac stress testing could be ordered in all cases, in accordance with the American Heart Association and American College of Sports Medicine guidelines, or a moderate activity program can be prescribed with cautious initiation and progression. Cardiac stress testing is indicated before a vigorous exercise program is implemented. The patient and family may wish to be involved in this choice.

Noncardiac conditions influence exercise plans. For example, exercise increases insulin sensitivity and reduces insulin requirements in the diabetic patient. These patients should monitor glucose levels and adjust hypoglycemic regimens when increasing activity. Because exercise can transiently increase blood pressure in persons with hypertension, it is ideal to check blood pressure before, during, and after exercise at least during exercise initiation. The proposed exercise plan can be adapted for chronic conditions both to benefit specific needs and to avoid problems (see Table 42-2).

  1. PATIENT GUIDELINES

The health care provider should offer general safety guidelines to the older adult who plans to exercise in an unsupervised setting (Table 42-3). Many web sites offer extensive advice about safety. Some of the key recommendations are to start low and go slow, to increase duration before increasing intensity, to stay well hydrated, to monitor exertion, and to discontinue if serious symptoms develop.

  1. EXERCISE ADHERENCE

Convincing an older sedentary person to exercise can be a formidable challenge. Modern civilization has created a living environment that, although immeasurably beneficial, reduces the need for physical activity in daily life. Modern transportation and labor-saving devices mean many people can go years without needing to walk further than a block or performing any physically demanding activity. The reduced demands for physical capacity in modern society have 2 negative effects on physical function. First, a great deal of capacity can be lost without detectable symptoms or limitations. Second, interventions are difficult to build into daily routines. One can get through the day with little physical demand and must intentionally add “nonessential” obligations to build up physical capacity.

Preventive interventions can be difficult to implement. Preventive actions such as taking a pill for blood

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pressure reduction may demand less of the individual than undertaking an exercise program. Preventive aims such as weight reduction, quitting smoking, or increasing exercise require the individual to make a significant behavior and lifestyle change. Although many behavior change strategies have been proposed, and a few tested, most have only a modest effect on the target behavior. The new behavior is frequently short lived, and benefits are not sustained. Given all the challenges of inducing behavior change and the constraints on time and resources available to the clinician, many proposals for the clinician's role in promoting exercise behavior seem daunting and not feasible. Although there are no simple answers, useful suggestions and guidelines are provided in Table 42-4. Adherence is improved when an individual commits to personally meaningful and measurable goals, decides on and uses a self monitoring plan such as a calendar or record of exercise, receives specific feedback such as objective increase in performance, and has access to support as desired from others. A physician's formal recommendation to exercise, delivered as a prescription based on individualized risks and needs, increases motivation and adherence.

Table 42-3. General patient instructions for exercise.

1. Start slowly and increase gradually.

2. Avoid holding your breath.

3. If you are on a medication or have a heart condition that changes your natural heart rate, do not use your pulse rate to judge how hard you should exercise.

4. Use safety equipment as recommended for the activity.

5. Drink plenty of fluids if doing activities that make you sweat unless your doctor has asked you to limit fluids.

6. Bend from the hips, not the waist, when bending forward.

7. Warm up muscles before stretching.

8. No exercise should be painful.

9. You can find the right amount of effort using the guideline “If you can talk without any trouble at all, your activity is probably too easy. If you cannot talk at all, it is too hard.”

10.                   Always include a warm-up and cool-down with an activity that moves your body but doesn't tire you.

Adapted from National Institute on Aging:Exercise for older adults: http://www.nihseniorhealth.gov/exercise/toc.html

Older adults need a choice of sites and schedules. Some may prefer group activities with supervisors in community settings, whereas others may prefer to exercise alone at home. For many older adults, a socialization opportunity is a key to continued motivation. Cost and access are important considerations. Many older adults prefer modest rather than high-intensity exercise and may have strong personal preferences about public changing facilities and privacy.

For the clinician, adherence-promoting concepts can be translated into actions. A health risk appraisal presents the individual with a personal profile of health risks and potential benefits of exercise. For example, a patient with mild hypertension and osteopenia could undergo blood pressure and bone density assessments; office testing of endurance, strength, and balance using a 6-min walk test; and performance tests such as timed repeated chair rises and tandem stands. The patient could respond to a questionnaire about activity practices and preferences. The results can be presented as a personalized summary of health status and future health risk, linked to specific exercise recommendations.

Table 42-4. Strategies to promote physical activity in older adults.

11.                   Personal and interpersonal

1. Goal setting

2. Self-monitoring

3. Feedback

4. Support from family, friends, staff

5. Physician advice

12.                   Environmental and societal

1. Easy access to safe and low-cost exercise site

2. Opportunity for social interaction

13.                   Program factors

1. Choice of sites and schedules

2. Choice of activities and intensity

The next step is to determine individual goals, interests, and barriers to exercise. The exercise recommendations should be derived from the individual's target accomplishments and preferences. Early success is a key to a positive outcome. Decide on modest initial goals, write them down as a prescription, and follow up in a few weeks to help motivate the patient. For example, a person with subclinical disability may wish to become less dyspneic when carrying groceries or laundry. She may prefer to exercise at home because she is a caregiver. An initial goal might be to start neighborhood walks or slow stair climbing for 5 min at a time a few times a day 4–5 days/week. The patient might keep a calendar or diary of exercise distance and time. The exercise is to be done at a pace that can be sustained but feels moderately tiring as demonstrated by increased work of breathing or gradual muscle fatigue. A return visit in a few weeks offers an opportunity to discuss initial challenges and successes. Repeated measures of symptoms and physical performance can be used as a feedback measure of progress. Reimbursable encounter time focused on exercise prescription can be linked to many cardiopulmonary or neuromusculoskeletal conditions in which exercise is medically recommended.

General Physical Activity

  1. PRINCIPLES & BENEFITS

General physical activity is a measure of overall energy consumption. Higher levels of physical activity have been repeatedly linked to reduced morbidity and mortality in epidemiological studies. Physical activity has been linked to reduced problems with heart disease, diabetes, and osteoporosis and improved mental well-being. Because many older adults have asymptomatic deconditioning, they have very little reserve if faced with any event or process that exacerbates the problem. In this sense, physical activity can increase physiological reserve and tolerance to stress. General physical activity differs from exercise in that the latter is more formally defined. Exercise is characterized by specific activities with expected physiological responses. Exercise is structured, scheduled, and repeated, whereas physical activity represents accumulated energy expenditure over time in all activities. General physical activity may not

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achieve the increased fitness levels that can be expected with formal endurance training. Physical activity can be expected to reduce the risks and complications of many chronic conditions and to increase well-being.

Using the framework described in Table 42-5, the older adult can be clinically “staged” by the kind of activity that causes fatigue or dyspnea and by the frequency and duration of energy-consuming activity. Energy demands are often compared in units called metabolic equivalents, or METS. Energy demands are based on oxygen or calorie consumption. The MET is a ratio comparing the energy consumption of an activity to energy consumption at rest. Oxygen consumption is often presented in milliliters per kilogram per minute. Oxygen consumption at rest (the resting metabolic rate) is ~3.5 mL/kg/min. A 3-MET activity consumes 3 times the oxygen per kilogram per minute, or ~10.5 mL/kg/min. Energy consumption can also be assessed in terms of caloric expenditure. The resting metabolic rate is about 1 kcal/kg/h. A 3-MET activity that is performed for 30 min (0.5 h) by a 50-kg person consumes 3 METs × 50 kg × 0.5 h, or 75 calories. Estimates of the metabolic demands of various activities are based on averages from several sources and are summarized by the American College of Sports Medicine in the Compendium of Physical Activities. These estimates are based on studies of healthy adults. Many conditions such as neurological or musculoskeletal problems decrease the metabolic efficiency of movement and increase the metabolic demands of activity. There are no studies of the energy demands of activities done by healthy or frail older adults. Because energy use may be more inefficient in many older adults, metabolic demands of activities may be somewhat higher than listed in Table 42-5. For this reason, the best use of the METs and activity table is to create a hierarchy of activities. The hierarchy can be used to gauge relative energy capacity between older adults and to select gradually increasing energy demanding activities for exercise prescription.

It is possible to link MET estimates to performance measures that can be done in the clinic or other health care settings. Table 42-6 relates walking speed in miles per hour and METS to walking speed, 6-min walk distance, 400-m walk time, and typical history. Walking speed test procedures are not yet standardized; distances and instructions vary. Table 42-6 lists walking speeds in meters per second over a 4-m course at a usual pace. If the timing of the walk starts from a standing position, then a period of acceleration is included, and walking speed calculations will underestimate actual walking speed. If the timing starts after the patient has started walking (a rolling start), then gait speeds are fairly consistent over various distances from 8 ft to 50 m. The 6-min walk distance or 400-m walk time can be used to estimate walking time in miles per hour and then METs. Many people who walk slowly (especially < 2.5 mph) may be unable to walk for the whole 6 min without rests and may have walk distances that are lower than those listed in Table 42-6.

Table 42-5. Physical energy demands of common activities.

MET

Representative activities

1.0

Sitting quietly, sleeping, watching television

1.5

Eating, sitting and talking, playing cards

2.0

Bathing while sitting, making the bed, driving a car, slow walking on level ground at < 2 mph

2.5

Dressing, shaving, sweeping or vacuuming floors, cooking, filling gas tank, riding lawn mower, walking on level ground at 2 mph

3.0

Walking on level ground at 2.5 mph, descending stairs, very light stationary bicycling (50 watts), very light weight lifting, slow dancing, bowling

3.5

Walking and carrying 15-lb load, food shopping with cart, golfing with cart, walking level ground at 3 mph

4

Showering while standing, toweling off, leisure bicycling, treading water, fishing, sweeping floors, raking lawn, playing with children, walking at 3.5 mph

4.5

Washing windows, washing car, mopping floors, weeding, mowing lawn with power mower, doing home calisthenics

5

Walking upstairs with light load, digging in garden

5.5

Square or folk dancing, scrubbing floors, house painting, stationary bicycling at 100 watts

6

Walking up hill at 3.5 mph, walking up stairs with moderate load (16–30 lbs), moving furniture, tilling garden, mowing with push mower, shoveling snow, light swimming

7

Playing tennis, backpacking, walking up hill with light load, stationary bicycling at 150 watts (moderate effort)

8

Carrying up to 50 lbs up stairs, slow lap swimming, race walking or slow running at 5 mph, walking up hill with moderate load

Adapted from American College of Sports Medicine: ACSMResource Manual, 3rd edition. Williams & Wilkins, 1998. Used with permission.

Table 42-6. Translating walking speed: clinical assessment of energy capacity.

Functional status

Miles per hour

Meters per second:

6-min walk distance

400-m walk time

METs

Typical history of fatigue with activity

Stand

Roll

Meters

Feet

Overt
   disability

1.0

0.41

0.46

165

541

14 min 24 s

< 2

Self-care, walking very short distances

1.5

0.57

0.69

248

813

9 min 36 s

< 2

 

Sub clinical
   disability

2.0

0.75

0.93

335

1098

7 min 12 s

2.5

Household activities, walking .25
   mile

2.5

0.88

1.15

414

1358

5 min 45 s

3.0

Carrying groceries or light yard
   work

Usual healthy
   elders

3.0

1.0

1.38

497

1630

4 min 48 s

3.5

Moderate housework, climbing
   several flights of stairs

3.5

1.1

1.60

576

1889

4 min 7 s

4.0

Carrying loads up stairs or up hills,
   heavy household or yard work

Fit elders

4.0

1.25

1.84

662

2171

3 min 36 s

> 4

Heavy work or sports

           

METs, metabolic equivalents.

           

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The ability to sustain a given MET level is an important part of endurance. Many sedentary older adults are able to sustain a moderate MET level for only a few minutes. For this reason, the exercise program often must begin with a gradual increase in duration of exercise before any effort to increase the MET intensity is even considered.

  1. ACTIVITIES & PRESCRIPTION

A medical assessment evaluates the medical safety for exercise and modifications for specific conditions. The practitioner is often expected to approve a proposed exercise program, including appropriate types of activity and related patient safety instructions. The physical activity prescription is based on the individual's current health and physical activity level. The current public health recommendation for older adults is to accumulate 30 min of moderate physical activity on most days of the week. This averages out to about 100 calories/day expended in moderate exercise. For every activity level, the prescription includes frequency, duration, intensity, warm-up and cool-down, stretching and other precautions, and progression. All activity should begin with a warm-up of somewhat easy activities that slightly increase energy demands. After the warm-up, the individual should stretch all major muscle groups using slow stretches that last ~30 s. Stretching helps reduce risk of injury in older adults and is safer and more effective after a warm-up. The cool-down after exercise is also important. This is the transition phase for heart rate and oxygen consumption to return to resting level. Slower walking or biking are appropriate activities. The intensity of physical activity that will have a training effect but be tolerable can be estimated from a person's predicted MET level. The predicted MET level can be based on history and clinical assessment. The proposed activities should be in the upper range of energy expenditure for the individual (Table 42-7). The recommended duration of activity, often 30 min or more in younger people, may be intolerable for more deconditioned older adults. Brief episodes of activity lasting 5–10 min several times per day can help build toward more sustained activity. All programs should progress over time. In the more frail, duration is progressed toward bouts of activity that last 20–30 min, before intensity is increased. It can take weeks or even months to reach this goal. The rate of progression can be gauged by perceived difficulty using the Borg Scale, ranging from 1 (very, very light) to 20 (very, very hard). The target is “somewhat hard”, or in the 12–13 range. This degree of difficulty can be described as “not hard enough if it is easy to talk but too hard if one can't talk while doing it.” Physiological effects of training take days to weeks to emerge. Progression based on physiological response in healthy adults is based on an increase in METs no more than every few weeks.

Aerobic Exercise

  1. PRINCIPLES & BENEFITS

Formal aerobic exercise is designed to increase fitness or aerobic capacity. Higher levels of fitness have been associated with reduced mortality and can increase reserve and resistance to deconditioning. Structured aerobic exercise is more targeted than general physical activity toward increasing cardiopulmonary fitness. Specific aerobic

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training can probably achieve greater gains in cardiopulmonary fitness than can physical activity alone.

Table 42-7. Physical activity prescription by patient type.a

Patient type

Intensity (METs)

Duration (minutes)

Frequency

Examples of exercise

Overt disability
   Recently bed bound

1.5

5-10

Several times per day

Sitting ADL, passive and active range of motion, progress to standing and walking

   Nonambulatory

2

5–10

Several times per day

Self-propel wheelchair, seated self-care, upper extremity games and activities individually and in groups

Subclinical disability Very sedentary

3

5–10

Several times per day

Slow walking program, group recreation

   Inactive

4

20 or more

Most days of the week

Walking, gardening, housework, bicycle

Usual aging

4–5

30

Most days of the week

Brisk walking, stair climbing, moderate endurance recreation

Fit

5 +

30 or more

Most days

Moderate to high intensity:very brisk walks on uneven surfaces and hills, brisk stair climbing, moderate to vigorous sports

METs, metabolic equivalents; ADL, activity of daily living.

aPrescribing exercise: (1) Let the patient select the preferred mode of activity; (2) start with an intensity and duration that is well tolerated; (3) initial exercise sessions should be observed if there has been no recent moderate activity; (4) initial sessions of moderate activity should include assessment of blood pressure and heart rate; (5) increase duration to a target training level (20–30 min or a set of 10 reps) before increasing intensity; (6) teach about self-monitoring of effort.

Cardiopulmonary fitness is generally assessed as maximal exercise capacity, measured as maximum oxygen consumption or Vo2max. Maximal exercise capacity is influenced by heart rate, cardiac stroke volume, and peripheral oxygen extraction. Older adults who undergo training have been shown to have demonstrable improvements in Vo2max attributable to improvements in cardiac stroke volume and oxygen extraction. Aging itself limits peak performance but not the ability to benefit from training.

  1. PRESCRIPTION & ACTIVITIES

Unsupervised physical activity rather than unsupervised formal aerobic training is appropriate for persons who have clinical or subclinical (difficulty performing self-care activities) disability and cannot exercise continuously at a moderate intensity. Supervised aerobic training may be appropriate as part of a structured and supervised restorative program. Unsupervised formal aerobic training is appropriate for healthy older adults who are able to walk steadily at a brisk pace. Healthy older adults may desire greater gains from exercise than they can achieve with a general physical activity program, in large part because vigorous activity is more effective at increasing aerobic capacity than is moderate activity.

The training program is likely to include more vigorous activity, justifying stress testing for sedentary and untrained adults. The same processes of warm-up, stretch, exercise, and cool-down should be followed. For structuring training, heart rate or perceived exertion can be used. Maximum predicted heart rate is traditionally estimated as 220 — age. The training range is considered to be 60–90% of maximum heart rate. Moderate training is at a heart rate of 50–70% of predicted maximum. A higher percentage of predicted maximum is for vigorous exercise. Heart rate estimates are not useful in the presence of any condition that alters heart rate response to exercise, such as the use of β-blockers, some pacemakers, and many atrial arrhythmias.

The Borg Scale of perceived exertion can also be used to target intensity. Another way of describing vigorous intensity is that it should induce sweating over time but be sustainable without exhaustion. Training should start with a moderate intensity pace and duration. Intensity can be increased with interval training, in which the individual establishes a tolerable MET level and adds brief periods of increased intensity every 5–10 min. The goal is to gradually increase the duration of the higher intensity intervals. Cross-training promotes variability in the program. Activities such as swimming and use of exercise equipment that requires

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upper extremity effort can complement lower extremity training and reduce boredom. Upper extremity exercise induces a higher heart rate response per MET level than does lower extremity training. Many people have more deconditioned arms than legs. The Borg Scale perceived exertion should be used to estimate intensity of upper extremity exercise. Initial durations may be much briefer than with lower extremity exercise.

Strength Training

  1. PRINCIPLES & BENEFITS

Aging is associated with loss of muscle mass and power. Loss of muscle mass is sarcopenia, similar to the loss of bone mass, or osteopenia The loss of muscle mass with age has been attributed to both smaller and fewer muscle cells. Muscle power is affected by both muscle mass and nervous system factors involving every level from the brain to the neuromuscular junction. Thus, muscular performance can improve faster and to a greater extent than can be attributed to increased muscle mass alone. Both muscle mass and power are responsive to exercise in older adults. The increase in muscle mass with exercise not only improves strength but also contributes to improved carbohydrate and lipid metabolism.

Muscle strength can be measured in many ways. The numerous and variable strength assessment techniques make it difficult to interpret and compare training programs and relative strength gains. Some measures of strength are reported in kilograms or pounds, as in 1-repetition maximum or isometric strength. The 1-repetition maximum (1-rep max) is the maximum mass that can be moved in a given maneuver, such as knee extension. Peak isometric force is the maximum force that can applied without moving (a single muscle length) using a dynamometer. Isokinetic strength measures the peak or average force applied by a muscle group through the range of motion at a given distance and speed of contraction. Isokinetic strength is reported in foot-pounds or Newton-meters. Power is often measured across multiple muscle groups in the lower extremity. This measure incorporates the rate of force development and is measured in Newton-meters per second. Functional strength is affected not only by the absolute ability to generate force but also by the ability to generate force across the varying lengths of the muscle during movement. The relationship between gains in force production and power are not linear and are not well understood. The muscle must perform at speeds that are useful for functions such as stopping a fall. Muscles need to work both when they are getting shorter (a concentric contraction) and to control the rate of lengthening, as in sitting down (an eccentric contraction). Isokinetic strength assessments can measure either concentric or eccentric contractions. Muscle endurance is a marker of the ability to sustain contractions. Some dynamometers can be used to assess the ability to sustain an isometric contraction.

The evidence linking strength to function is variable. Some of this variability is attributable to the diversity of strength measurement techniques. In addition, the relationship between strength and function may not be linear. There may be thresholds that define strength requirements for usual functions. Persons who are very weak could increase strength without reaching the minimal threshold for an activity. For example, a bed-bound person could increase leg strength without achieving the minimal strength requirements needed for climbing stairs. Healthy persons may already be capable of many functions, and further strength gain could increase reserve without a detectable effect on usual function.

  1. PRESCRIPTION & ACTIVITIES

Strength gain is important for almost all older adults, from the most disabled to the most fit. Programs can be offered at intensity levels from light to vigorous. Medical concerns relate primarily to acute energy demands on the cardiovascular system and the need to avoid injury. Strength training is appropriate for persons with many chronic conditions.

The main safety rules for strength training are to breathe properly and to move in a smooth and controlled fashion. The most important breathing guideline is to avoid holding one's breath, which induces increased internal body pressure (the Valsalva maneuver). Other breathing guidelines are to start with taking a breath before lifting, exhaling during lifting, and inhaling during controlled release. Smooth movement means that the muscle moves against resistance at a steady rate without shaking or jerking.

Strength training can incorporate body weight for resistance or low-tech items such as elastic bands, wrist, and ankle weights, free weights, or household items like milk jugs and tin cans. Strength equipment can offer safer ways to lift heavier weights and can provide complex systems to control the rate of muscle contraction. For most older persons with clinical or subclinical disability, simpler weight training equipment is probably sufficient.

For all types of older adults, the program should start with a baseline assessment of intensity. Intensity is determined as a level of resistance for each major muscle group in the upper extremity, lower extremity, and trunk. A proper level of resistance is one in which a set of 8–15 repetitions feels somewhat hard but can be completed using smooth control. Intensity can be prescribed as a percentage of the 1-rep max as well. For each level of intensity, sessions are repeated 2 or 3 times

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per week until 1 or 2 sets of repetitions can be done in a smooth manner. Resistance can then be increased. There is no clear evidence that training more frequently or increasing the number of sets accelerates gains in frail persons. More rapid increases in intensity and more frequent training can increase the risk of injury. Healthy elders may be interested in a more aggressive program and can participate in most community-based programs. For the very frail, body weight offers sufficient resistance for initial training. Using body segment weight alone for training is similar to active range of motion. Bearing the weight of the whole body in standing, transfers, and walking is a strength training activity for many frail elders.

Balance Training

  1. PRINCIPLES & BENEFITS

Balance exercise training can improve markers of stability and reduce fall rates. Balance can be described in biomechanical or in physiological terms. From a biomechanical perspective, balance is the ability to control the displacement and recovery of the moving mass of the body over the base of support. The base of support is the contact surface of the body with the support surface, as in the feet with the ground or the buttocks with a chair. Static balance is the ability to remain upright when controlling the mass of the body over a fixed base of support, as in standing. Better balance involves remaining upright on a smaller base of support and being able to move the mass of the body further toward the margins of the base of support. Dynamic balance is the ability to control the mass of the body over a moving base of support, as in walking. Mobility requires dynamic balance. Improved dynamic balance involves more rapid and accurate corrections of the moving base of support as the body mass moves.

A physiological approach to balance incorporates the detection, planning, and execution of the movements required to remain upright. Balance reactions can be corrective, as in responding to a push, or anticipatory, as in planning to step over an obstacle. Although most balance assessment has been static and corrective, the balance requirements for mobility are mostly dynamic and anticipatory. The physiological subsystems of balance include sensory, central processing, and effector factors. There are 3 sensory systems: vision, vestibular, and somatosensory. Central processing requires alertness, attention, integration of sensory information, and response planning. Effector subsystems important for balance include strength and range of motion. Most balance training programs are based on biomechanical principles. Balance tasks are ordered in difficulty according to the size of the base of support and the speed and size of displacements of the body. For example, in static balance, standing with feet together is harder that standing with feet apart, and standing on 1 foot is even harder. Some balance training involves awareness of the shifting of weight within the base of support from 1 foot to the other. Stepping over obstacles requires planning and executing displacements while moving. Some balance training is specific to a physiological deficit such as vestibular dysfunction.

  1. PRESCRIPTION & ACTIVITIES

A global assessment of balance capacity can be obtained clinically with simple measures such as the Tinetti Performance Oriented Mobility Assessment, timed stands, or tandem walking. Persons who need assistive devices such as walkers for standing and walking by definition require a larger base of support and have limited balance. Balance training requires progression in difficulty, making it inherently somewhat more dangerous than other forms of exercise because there is an increased risk of falling.

Balance training for everyone but the healthy elder requires supervision. Balance training for the very frail person involves movement practice in a seated position that requires displacement of the trunk and arms. For the person who needs an assistive device, balance training often involves experience maneuvering around the home or while holding to a support surface. Persons with subclinical disability can practice maintaining static balance with a progressively smaller base of support while standing, walking with a narrow base of support, and controlling weight shift and lower extremity movement, as in playing catch with a ball or swinging a golf club. Healthy elders can improve balance through many recreational activities that require displacement and recovery, such as dancing or tennis.

Some forms of balance training target specific issues and opportunities. Tai chi ch'uan requires slow, controlled motions that involve displacement and recovery. There is a focus on body awareness. Balance training in water allows patients to explore the margins of their ability to displace and recover without fear of injury, because falls are cushioned by the water. Balance training with visual feedback involves force plates under the feet and a video monitor to show the location of the center of pressure. As weight is shifted forward, backward, and from side to side, a point on the screen moves, allowing patients to increase awareness of body position and control. They also get feedback that they are able to move closer and closer to the margins of the base of support, a sign of progress.

Flexibility

  1. PRINCIPLES & BENEFITS

Flexibility decreases with age and can become significantly restricted with disuse or disease. Loss of range of

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motion affects mobility and function. In the worst case, contractures occur, limiting walking, standing, and reaching. Flexibility is rarely an isolated deficit, because loss of mobility and movement also affect strength and fitness.

  1. PRESCRIPTION & ACTIVITIES

There are few contraindications to flexibility exercise. Even the bed-bound person with an injury or illness benefits from range of motion of uninjured body segments. Specific contraindications include acutely inflamed joints, joints that are therapeutically fused, and recent fracture. General light to moderate activity helps warm up the muscle before stretching for flexibility. Stretches should last 10–30 s and involve all the major joints of the upper and lower extremity and trunk. The stretch should cause a sensation of pulling but not acute pain.

Combined Programs

  1. PRINCIPLES & BENEFITS

Most older adults benefit from exercises that improve fitness, strength, balance, and flexibility. All components are needed to improved mobility and function. Many people who have frank or subclinical disability are so deconditioned and weak that almost all exercise stresses their limits and has a training effect.

  1. PRESCRIPTION & ACTIVITIES

The medical approval process for combined programs is based on the specific issues already described. Major constraints on combined programs are time and fatigue. It is usually unrealistic for a frail older adult to undertake a program that demands hours of exercise each day. This limited exercise capacity can be a barrier to formal rehabilitation programs that require 3 h/day of active therapy.

For healthy elders and those with subclinical disability, the challenge is to make the most of available time and energy. Some programs are based on alternating activities on different days. For example, one could walk ≥ 3 days/week and perform strength training 2–3 times/week on the “off” days. Some programs combine a mix of aerobic, strength, and balance activities into an hour-long session 3 days/week. Some activities can combine several goals. Stair climbing increases both muscle power and fitness.

EVIDENCE-BASED POINTS

  • Aging is associated with losses of peak fitness, strength, and flexibility, but training prevents or reverses some of these losses.
  • Exercise is safe and effective for most older adults, from the most frail to the most fit.
  • Exercise testing before moderate aerobic exercise in the asymptomatic older adult is controversial.
  • Regular exercise involves a behavior change that is hard to initiate and maintain.
  • The formal prescription of exercise by a health care provider increases patient exercise behavior.

REFERENCES

American College of Sports Medicine: ACSM position stand on exercise and physical activity for older adults. Med Sci Sports Exer 1998;30:992. [PMID: 9624662] (Primary source for current recommendations and evidence-based justification for exercise in older adults.)

American College of Sports Medicine: ACSM Resource Manual, 3rd edition. Williams & Wilkins, 1998. (Core reference for exercise physiology, prescription, and management.)

Chakravarthy MV et al: An obligation for primary care physicians to prescribe physical activity to sedentary patients to reduce the risk of chronic health conditions. Mayo Clin Proc 2002;77:165. [PMID: 11838650] (Summary of the physiological effects of exercise on chronic health conditions.)

Chandler JM, Hadley EC: Exercise to improve physiologic and functional performance in old age. Clin Geriatr Med 1996; 12:761. [PMID: 8890115] (Review of the exercise evidence in the literature.)

Christmas C, Anderson RA: Exercise and older patients: guidelines for the clinician. J Am Geriatr Soc 2000;48:318. [PMID: 10733061] (Overview of the evidence for the benefits of exercise in older adults.)

Gill TM et al: Role of exercise stress testing and safety monitoring for older persons starting an exercise program. JAMA 2000; 284:342. [PMID: 1089166] (Summary of the evidence and discussion of the issues related to stress testing before exercise in older adults.)

Judge JO: Physical activity. Clin Geriatr 2001;9:19. (Practical guideline to promoting physical activity.) (PMID: not available)

Keysore JJ, Jette AM: Have we oversold the benefits of late-life exercise? J Gerontol MS 2001;56A:M412. [PMID: 11445600] (Thoughtful summary of exercise intervention trials.)

King AC: Interventions to promote physical activity by older adults. J Gerontol MS 2001;56A:M36. [PMID: 11730236] (Summary of behavioral principles, strategies, and future issues to promote exercise in older adults.)

Mazzeo RS, Tanaka H: Exercise prescription for the elderly: current recommendations. Sports Med 2001;31:809. [PMID: 11583105] (Overview of key aspects of exercise prescription, especially for endurance and strength.)

O'Grady M et al: Therapeutic and physical fitness exercise prescription for older adults with joint disease: an evidence based approach. Rheum Dis Clin North Am 2000;26:617. [PMID: 10989515] (Thoughtful discussion of exercise benefits and recommendations for exercise adaptation for older persons with arthritis.)

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Van der Bij AK et al: Effectiveness of physical activity interventions for older adults. Am J Prev Med 2002;22:120. [PMID: 11818183] (Overview and summary of the evidence on interventions designed to promote exercise adherence in older adults.)

Vincent KR et al: Resistance exercise and physical performance in adults aged 60 to 83. J Am Geriatr Soc 2002;50:1100. [PMID: not available] (Report of a randomized controlled trial in healthy elders of 2 levels of resistance training.)

Wu G: Evaluation of the effectiveness of Tai Chi for improving balance and preventing falls in the older population-a review. J Am Geriatr Soc 2002;50:746. [PMID: 11982679] (Review of the various forms of Tai Chi Ch'uan and a summary of the evidence to date of its effectiveness on maintaining balance.)