Perspectives in Disease Prevention and Health Promotion Status of the 1990 Physical Fitness and Exercise Objectives
Eleven of the U.S. Public Health Service's 1990 Objectives for the Nation concern physical fitness and exercise (1). When the objectives were developed in 1980, less baseline information was available for physical fitness and exercise than for most other areas. During the ensuing 5 years, considerable progress has been made toward clarifying the relationship between physical activity and health and in collecting previously unavailable information about the activity levels of children and adults. Several of the objectives are likely to be achieved by 1990 (Table 2). Nevertheless, much remains to be learned and most segments of society would benefit from increased levels of physical activity. The following is a brief summary of the current status of the 1990 objectives on physical fitness and exercise. HEALTH EFFECTS
The established beneficial effects of physical activity on health include reduced risk of coronary heart disease (CHD), desirable weight control, and reduced symptoms of anxiety and mild to moderate depression (2-4). Beneficial effects on the prevention and control of hypertension, diabetes, osteoporosis, and certain psychiatric and psychologic conditions appear likely but are less firmly established (2,4). The temporarily increased risk of sudden death during vigorous physical activity is outweighed by the overall reduced risk of CHD from habitual vigorous activity (2). Information about the incidence of musculoskeletal injuries and other possible adverse effects is not available (5). PREVALENCE OF APPROPRIATE PHYSICAL ACTIVITY PRACTICES
Three of the objectives on physical fitness and exercise pertain to the prevalence of participation in appropriate physical activities of specific age groups. For the 1990 objectives, appropriate physical activity is defined as that which produces moderate to high levels of cardiorespiratory fitness and, therefore, has the following four characteristics: (1) rhythmic contraction of large muscle groups; (2) intensity that requires 60% or more of maximal aerobic capacity; (3) frequency of three or more sessions per week; and (4) duration of 20 minutes or more per session. For children, appropriate activity is also required to be able to be continued into adulthood (e.g., requires only one or two persons to do the activity).
Few of the surveys of the activity patterns of persons in the United States have obtained information compatible with this definition. None of the definitions of physical activity used in past surveys are similar enough to each other to allow comparison of results (6). National polls and data from selected population groups suggest the amount of time spent by adults in vigorous leisure-time activity has increased in the past 10-20 years (6,7), but the data do not allow a quantitative estimate of the increase.
The prevalence estimates from sources using a definition of appropriate physical activity suggested in the 1990 objectives are shown in Figure 1. The estimate for children and adolescents is adapted from the National Children and Youth Fitness Survey (8), the estimates for adults are based primarily on unpublished data from 16 states that participated in the 1984 CDC-State Behavioral Risk Factor Surveillance System.
The fourth objective in this area concerns the level of participation in public programs and trends in the pattern of physical activity. No information is available about the use of public facilities. Most surveys show the most commonly reported leisure-time physical activities by adults are walking, swimming, calisthenics, bicycling, and jogging or running. Variation in definition of participation precludes any assessment of national trends in the absolute or relative frequencies of these activities. AWARENESS
Unpublished data from surveys conducted in a Dallas, Texas, suburb and in Los Angeles, California, indicate that over 70% of adults know that vigorous physical activity needs to be done three or more times per week and maintained for 20 minutes or more per session to promote cardiovascular fitness. Fifty-nine percent to 90% of the time, respondents to the Los Angeles survey and to the Perrier survey (9) correctly identified specific activities that are vigorous enough (e.g., running, swimming); only 10%-58% of the time did they correctly identify activities that are not vigorous enough (e.g., baseball, bowling, golf).
Surveys of physicians in Massachusetts and Maryland indicated that just under 50% of primary-care physicians routinely inquire about their patient's exercise practices (10,11). Whether the inquiries include questions about the frequency, duration, and intensity of the exercise, as suggested by the 1990 objectives, is unknown. WORKSITE FITNESS PROGRAMS
A great deal has been written about worksite fitness programs. However, data are currently not available to describe the prevalence of programs because: (1) existing studies have been limited to particular states or industries; (2) different definitions of fitness or exercise programs have been used; (3) existing studies were not based on representative samples or have had very low response rates; and (4) the studies focused on the company or organization, not on individual worksites.
Similarly, data are not available to determine the effects of participation in fitness programs on job performance and health-care costs. CHILDREN AND ADOLESCENTS
Overall, approximately 36% of children and adolescents, ages 10-17 years, participate in daily physical education programs (12). This is essentially unchanged since 1974 and well below the 1990 objective of 60%.
Methods of determining the fitness of children and adolescents are available, and surveys have been conducted. It is not known how many participate in such tests annually. Reported by President's Council on Physical Fitness and Sports; Behavioral Epidemiology and Evaluation Br, Div of Health Education, Center for Health Promotion and Education, CDC.
Editorial Note: The 1990 objectives consist of 223 discrete objectives in 15 broad areas, such as Family Planning, Toxic Agent Control, and Smoking Control (1). They were developed in 1980 through the combined efforts of over 500 representatives of the public and private sectors and are useful national guidelines in need of periodic evaluation, rather than rigid obligations. If achieved, the health status of the people of the United States would be appreciably improved (1).
Even though several of the objectives in the area of physical fitness and exercise are not likely to be achieved, considerable progress has been made. Research on the various health effects of physical activity has progressed, but more is needed. Surveys by the National Center for Health Statistics, projects sponsored by the Office of Disease Prevention and Health Promotion, and CDC will provide valuable information about the prevalence and trends of certain physical activity patterns. Promotional efforts by the President's Council on Physical Fitness and Sports and a variety of public and private agencies are likely to favorably influence the knowledge, attitudes, and practices of U.S. citizens with respect to the benefits of appropriate physical activity.
A few particularly noteworthy issues deserve comment. First, many important questions remain about the salubrious effect of physical activity on CHD. Several careful observational studies of the association between activity and CHD document that the risk of CHD is reduced among more active persons (13-18). Evidence suggests that this is not entirely due to the selection of a more active life style by those who are intrinsically less susceptible to CHD (2). In fact, the reduction in risk appears to be relatively greater for persons who are obese or have hypertension (19). Nevertheless, several important areas need more research. More information is needed about the dose-response effect of physical activity on CHD, the effects on CHD of beginning a more active life style in the middle or later years, and the factors that affect the risk of sudden death during exercise. These and other research needs are listed elsewhere (2). Resolution of these issues would provide better and safer recommendations about how to reduce the risk of CHD through physical activity.
A second and related issue concerns the type and intensity of physical activity appropriate for inclusion in national objectives, such as the 1990 Objectives for Physical Fitness and Exercise. The definition of appropriate physical activity set forth by the 1990 objectives is rigorous, and only 10%-20% of the adult population is presently meeting it. Persons who achieve the level recommended by the 1990 objectives probably attain the maximum reduction in CHD risk available through physical activity. However, less vigorous activity also appears to be helpful. In fact, the relative reduction in risk of CHD appears to be greatest as those with the least physically active life style become just a little more active (20). Additionally, some of the health benefits to be achieved through activity do not seem to require vigorous physical activity. Osteoporosis appears to be retarded simply by being in an upright
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