Page 866 - Cardiac Nursing

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CHAPTER
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E E E E Exercise and Activity
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Jonathan Myers
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Si Sincee thee late 1950s,, numerous scientific reports have examined re reccreational activities, are asssoociated with a decrease in morttality
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the relationshipps between physical activity, physical fitness, and ra ratess. 29
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cardiovascular health. Expert panels convenedd by organizations The landmark epidemiologic work of the late Ralphh Paffen-
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such as thee Centers ffor Diseasee Controll andd Prevention (CDC), 1 ba barger and associates among Harvard alumni 6,29–33 has been par-
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the American College of Sports Medicine (ACSM), the Institute ticularly persuaasive inn support f physicall activity a dnd therefore
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of Medicine (IOM)), andd he AAmerican Heart Association the development of the CDC, AHA, IOM, and ACSM guide-
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(AHA), along with the 1996 U.S. Surgeon General’s Report on lines. Table 37-1 illustrates the rates and relative risks of death
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Physical Activity and Health, have reinforced scientific evidence over a 9-year period among 11,864 Harvard alumni by patterns of
linking regular physical activity to various measures of cardiovas- physical activity. Several findings in Table 37-1 are particularly
cular health. The prevailing view in these reports is that more ac- noteworthy. The largest benefits in terms of mortality appear to
tive or fit individuals tend to experience less coronary heart disease occur by engaging in moderate activity levels; moderate is gener-
(CHD) than their sedentary counterparts, and when they do ac- ally defined as activity performed at an intensity of 3 to 6 meta-
quire CHD, it occurs at a later age and tends to be less se- bolic equivalents (METs) (a multiple of the resting metabolic
vere. 1,2,5–7 Cardiac rehabilitation, as an industry, has evolved in rate), approximately equivalent to brisk walking for most adults. 34
large part because of the abundance of scientific evidence indicat- Note also that regular moderate walking or sports participation is
ing that regular exercise improves physical function and reduces associated with 30% to 40% reductions in mortality compared
the risk of reinfarction and sudden death in patients with known with more sedentary individuals (relative risk of death 0.60 to
CHD. 8–12 Despite this evidence, however, most adults in the 0.70). Likewise, the physical activity index, expressed as kilocalo-
United States remain effectively sedentary, 2,3,7 and the vast ma- ries per week (the sum of walking, stair climbing, and sports par-
jority of patients who sustain a myocardial infarction (MI) are not ticipation) suggests that a 40% reduction in mortality occurs by
referred to a cardiac rehabilitation program. 13 This is caused in engaging in modest levels of activity (1,000 to 2,000 kcal/week,
part by the fact that physical activity is not currently integrated equivalent to three to five 1-hour sessions of activity), whereas
into the U.S. health care paradigm, and the majority of physicians only minimal additional benefits are achieved by engaging in
fail to prescribe exercise to their patients. 14–17 greater-intensity activity. These findings agree closely with earlier
It is therefore incumbent on the nurse or other health care results among 16,936 Harvard alumni assessed in the early 1960s
provider to encourage patients to become more physically active, and followed for all-cause mortality for nearly 20 years. 30 Similar
to appreciate the role of rehabilitation in cardiac care, and to de- results have been reported from large studies that have followed
velop strategies that promote the adoption of physically active subjects for CHD morbidity and mortality in the range of 10 to
lifestyles in all their patients. This chapter describes the scientific 20 years among British civil servants, 35,36 U.S. railroad workers, 37
evidence linking physical activity and health, summarizes the San Francisco longshoremen, 33 nurses, 38–40 physicians, 41 U.S.
physiologic changes that occur with a program of regular exercise, Veterans, 42 and other cohorts (for review, see Kohl 19 or Pedersen
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and provides an outline for cardiac rehabilitation in the modern and Saltin ). Clearly, the evidence linking a physically active
treatment era. lifestyle and cardiovascular health is substantial.
Physiologic Fitness and Health
ROLE OF EXERCISE IN
CARDIOVASCULAR HEALTH A growing number of studies have been published in which phys-
ical fitness, determined by standardized exercise testing, was de-
Epidemiologic Evidence Supporting termined among large samples of men and women who have been
Physical Activity followed for the incidence of CHD morbidity and mortality for
up to 10 years. 42,44–49 Each of these studies demonstrated that
It has been estimated that as many as 250,000 deaths per year in higher levels of fitness were associated with lower rates of CHD or
the United States are attributable to lack of regular physical ac- all-cause mortality. It is important to note that these associations
tivity. 18 Ongoing longitudinal studies have provided consistent appear to be independent of other CHD risk factors. Also impor-
evidence of varying strength documenting the protective effects tant is that the low levels of fitness in these studies did not appear
of activity for a number of chronic diseases, including to be associated with subclinical disease.
CHD, 4,5,8–10,12,19,20 type 2 diabetes, 20–24 hypertension, 25 osteo- In a classic analysis, Blair et al. 44 assessed fitness by treadmill
porosis, 26 and site-specific cancers. 27 In contrast, low levels of performance in 10,244 men and 3,120 women and followed
them for 110,482 person years (averaging 8 years) for all cause
physical fitness or activity ar e consistently associated with them for 110 482 person - y ears (av eragi ng 8 y ears) for all - cause
physical fitness or activity are consistently associated with higherhigher
cardiovascular and all-cause mortality rates. 2,4,5,19,20,28 Midlife mortality. These results are presented in Table 37-2. Mortality
increases in physical activity, through change in occupation or rates were lowest (18.6 per 10,000 man-years) among the most fit
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