Promoting physical activity among older adults

Promoting Physical Activity Among Older Adults From Ecology to the Individual William A. Satariano, PhD, Edward McAuley, PhD Abstract:

The promotion of physical activity in older populations holds the promise of promoting health and reducing the risk of disablement. Individual- and community-based programs are often presented as being distinct and, in some cases, antithetical. The objective of this paper is to illustrate, through the use of an ecologic model, that individual- and community-based programs are complementary. The following topics are discussed: (1) the development of transdisciplinary theories; (2) the establishment of better measures to address the linkages across individual behavior, group behavior, the built environment, and the temporal sequence of biological, behavioral, and environmental factors; (3) the translation of research into practice and policies; and (4) the training of a new generation of scholars and practitioners to develop and execute research, practice, and policy agendas in this area. An ecologic model fosters a comprehensive agenda based on biological, behavioral, and environmental factors. The study of the interaction of the individual with the environment is challenging but potentially more important than the study of the role of the individual or the environment alone in the promotion of physical activity. (Am J Prev Med 2003;25(3Sii):184 –192) © 2003 American Journal of Preventive Medicine

Introduction

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hysical activity has been strongly associated with the preservation of physical and cognitive function and with the avoidance of limitations and disability in older populations. Despite the significance of physical activity in the preservation of health and functioning, the proportion of adults engaging in moderate and vigorous levels of physical activity declines with age.1 The promotion of physical activity among older adults has emerged as a national health objective.1 A variety of physical activity promotion programs have been developed, administered, and evaluated in older populations, with some of these programs focusing on the individual and others on the community. These approaches are often presented as distinct and, in fact, almost antithetical. Our primary objective is to demonstrate, through the use of an ecologic model, that the two approaches are indeed complementary. An ecologic model assumes that health depends on the dynamic interaction of biological, behavioral, social, and environmental factors, factors that interact over the life course of individuals, families, neighborhoods, and communities. The promotion of physical activity at the community level From the Division of Epidemiology, University of California–Berkeley (Satariano), Berkeley, California; and Department of Kinesiology, University of Illinois at Urbana–Champaign (McAuley), Urbana, Illinois Address correspondence and reprint requests to: William A. Satariano, PhD, School of Public Health, 140 Warren Hall, University of California–Berkeley, Berkeley CA 94720. E-mail: bills@uclink4. berkeley.edu.

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depends in large part on critical individual variables, such as a sense of control and self-efficacy. Likewise, promotion and, in particular, the maintenance of physical activity at the individual level depends on critical community variables, such as environmental and policy factors, such as well-maintained and well-illuminated sidewalks and pedestrian islands to ensure safety when crossing surface streets. Indeed, one of the most common theoretical models applied at the individual level, social cognitive theory,2 has at its heart the triadic reciprocal determinism involving the bi-directional influence on one another of personal factors (e.g., biology, cognition, affect), environmental factors, and behavioral patterns.3 Viewing these approaches as complementary will enhance both research and practice but, at the same time, present a number of significant challenges. Following an overview of individual- and community-based approaches, we address four challenges to the development, administration, and evaluation of a research and practice program of physical activity in older populations. These challenges include (1) the development of transdisciplinary theories from the ecologic model that will inform research and practice; (2) the establishment of better measures to address the linkages across individual behavior, group behavior, the built environment, and the temporal sequence of the interplay among biological, behavior, and environmental factors; (3) the development and evaluation of strategies for the “translation” of research into practice and policies; and (4) the training of a new generation of scholars

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and practitioners to develop and execute research, practice, and policy agendas in this area.

Disablement Process and Physical Activity Programs One of the most important questions to address is why some older adults are able to maintain their health and vitality and avoid functional limitations and disability, while others are not. Functional limitations are defined as restrictions in performing generic tasks that typically involve upper- and lower-body strength, balance, and fine dexterity. Disability, on the other hand, refers to the inability to perform specific social roles in everyday life because of health or physical problems.4 Following from an ecologic perspective, Verbrugge and Jette4 argue that the timing, severity, and distribution of disability in the population are based on the interplay of biological, behavioral, and environmental factors. The “disablement process” itself is characterized as being initiated by a pathology with an associated level of physiologic or cognitive impairment that may, in turn, lead to functional limitations and, ultimately, to a disability. The transition from pathology to disability, especially from functional limitation to disability, depends on the intersections of the individual’s capacity, behaviors, and the relative resources and demands of the social and physical environments. Physical activity is one such behavior that has been shown to affect the timing, severity, and progression of disablement. There is extensive research indicating that physically active older people are more likely than sedentary ones to preserve their health and functioning and consequently avoid functional limitations and disability.1

An Overview of Current Programs Although the “disablement model” has become a standard frame of reference in gerontology and public health, programs to promote physical activity in older populations have focused typically on the individual, almost in isolation from a consideration of the social and physical environments.5 Typically, these studies have employed derivatives of social cognitive/learning theories2 and have demonstrated the superiority of cognitive-behavioral strategies over basic instructional delivery or educational approaches.6,7 For example, King5 has contended that the combination of telephone supervision with home-based exercise programs is at least as effective in changing the level of physical activity in individual adults as is group-based instruction or face-to-face contact. Such findings have implications for reaching larger numbers of older adults at the individual level. While Abrams et al.8 have highlighted the numerous challenges associated with tailored communications research, a recent review of targeted and tailored physical activity interventions suggests that the delivery

of physical activity messages, advice, strategies, and prescriptions via print and telecommunications technology has met with some success (see Napolitano and Marcus9 for a review). Moreover, initial forays into the employment of technologies such as electronic mail and the Internet to change physical activity behavior appear promising.9 However, as Abrams et al.8 cogently note, much more work is needed before the gaps among technology, theory, and application can be closed. Although a plethora of studies target individual correlates of physical activity in older adults, it is abundantly clear that little is known about how such variables mediate or moderate the effects of intervention strategies on physical activity.10 The extent to which these individual factors interact with social and environmental factors is a high-priority challenge. There is also recent evidence that most physical activity programs are designed to reduce impairments and functional limitations but not disability. Based on a review of 31 studies, Keysor and Jette11 concluded that late-life exercise interventions improved strength, aerobic capacity, flexibility, walking, and standing balance. In contrast, of the few studies that focused on physical, social, emotional, or overall disability, few improvements were noted. Possible reasons for this finding include variations in sample size, differences in the type and length of the exercise intervention, inadequate sample size and power, and, most notably, shortcomings in the measures of disability used by the investigators. As noted previously, the concept of disability is based on the intersection of the capacity of the individual and the demands of the environment. Therefore, to measure disability properly, it is necessary, as argued by Keysor and Jette,11 to include that intersection as part of the assessment. While most programs focus on the individual and are designed to reduce impairments and enhance function rather than prevent disability, there is evidence, although admittedly from a limited number of studies, showing that environmental factors, such as characteristics of the built environment, affect patterns of function and disability.12 Those with greater access to either exercise equipment or walking paths are more likely to use those resources.12 There is evidence that characteristics of the physical environment and, more specifically, characteristics of neighborhoods, defined in a variety of ways, are associated with different health behaviors.13–15 For example, research from the Alameda County Study indicated that residence in an impoverished area was associated with a significant decline in levels of physical activity, after adjustment for other factors, including individual income, education, smoking status, body mass index, and alcohol consumption.13 In a separate study of neighborhood environments in Alameda County, residents aged ⱖ55 who reported specific problems in Am J Prev Med 2003;25(3Sii)

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their neighborhoods (i.e., traffic, noise, crime, trash and litter, poor street lighting, and transportation difficulties) were more likely than others to report difficulty in lower-extremity functional loss.16 The prospective association between reports of problematic neighborhoods and functional loss may be due to a number of factors, including neighborhood barriers to participation in physical activity. To date, however, there is no direct association between self-reported neighborhood problems and levels of physical activity. In fact, a British study17 reported an association between reports of neighborhood problems and poor self-rated health, psychological distress, and physical dysfunction. However, no association was found between neighborhood problems and health-related behaviors such as smoking, diet, alcohol consumption, and physical activity. There is also evidence that the characteristics of environments and, more specifically, characteristics of neighborhoods, are defined and categorized in a variety of ways. For example, environmental factors associated with the level of physical activity include accessibility of exercise facilities, parks, and walking trails, as well as the aesthetic qualities and character of neighborhoods. Although the examination of environmental factors is an important development in the promotion of physical activity in older adults, much of this research has been based on cross-sectional analyses, thus precluding any examination of causal patterns.12 Moreover, it is also unclear as to the roles played by individual behaviors and characteristics in such studies and whether reported relationships hold true across the life span. Of particular interest is the issue of how built environments and neighborhood accessibility facilitate or debilitate those individual variables that have previously been associated with physical activity in older adults (e.g., beliefs, motivations, sense of control, selfefficacy, and social support). A number of researchers have recently called for the incorporation of both individual-level and environmental-level factors in a truly integrated approach to physical activity research and practice in the elderly. For example, Keysor and Jette11 write: “Perhaps in addressing disability we need to target directly the person– environment interaction. Therefore, more research is needed to examine the mediating and moderating role of beliefs, emotions, coping strategies, and physical and social environments so that we can develop and evaluate interventions to enhance behaviors and reduce late-life disability” (emphasis added). King et al.18 have called for a “transdisciplinary paradigm” to address the multilevel life-course approach required to better understand and promote physical activity in older populations. The term “transdisciplinary” implies the use of the concepts and methods of a variety of scientific disciplines. Elsewhere, King et al.18 conclude that “research to elucidate mediating mechanisms to improve 186

population levels of physical activity is being revealed as a complex interaction of individual and contextual factors that no one discipline or level of analysis can adequately address.” It is only by including both individual and environmental factors that we can examine both the causes and risks of disability among individuals as well as the causes of the incidence and prevalence of disability in the population. According to Rose,19 the study of the causes or risks of an adverse outcome is typically based on a comparison between those with the outcome and those without. If both groups (causes and controls) reside in the same geographic area and share a number of characteristics and exposures, then the difference in outcome will depend on other individual exposures and, most notably, differences in individual susceptibility to the more common, shared factors.19 As Rose19 writes, “Epidemiology is often defined in terms of the study of the determinants of the distribution of the disease; but we should not forget that the more widespread is a particular cause, the less it explains the distribution of cases. The hardest cause to identify is the one that is universally present, for then it has no influence on the distribution of disease.”19 In contrast to the study of individual risk, the causes of the incidence and prevalence of disease can only be assessed at the population level and, more specifically, a comparison of one population with another. This means that it would be impossible to examine the causes of the incidence and prevalence of disability in a population without examining differences in environmental factors between populations, such as the level of “walkability” and location and access to different modes of transportation. Finally, as Rose concludes, “Many diseases will long continue to call for both approaches [individual and population], and fortunately competition between them is unnecessary.”19

Challenges of an Ecologic Approach Development of a Transdisciplinary Theory One of the significant challenges for physical activity promotion in older adults is to develop in more detail the transdisciplinary theory called for by King et al.18 This theory follows, in large part, from an ecologic model. Although the ecologic model has been presented in different forms,20 –24 the version presented in Healthy People 2010 25identifies the key generic elements (see Figure 1). This model serves as a foundation for the development of theories, such as the transdisciplinary theory, from which sets of testable hypotheses can be derived to describe and explain specific health and functional outcomes. The theory should include the following components. First, a theory should integrate biological, behavioral, social, and physical environmental factors. Some

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Figure 1. Determinants of health (detail). (From U.S. Department of Health and Human Services25)

researchers have used the metaphor of the Chinese box to characterize the multilevel quality (boxes within boxes) of an ecologic approach.23 Second, it should address a number of different outcomes, including pathology, impairment, functional limitations, and disability.4 Third, it should incorporate, as suggested by King et al.,18 the variable of time. Indeed, the interplay of biology, behavior, and the environment must occur over time. Time, in turn, can be defined in terms of human development at the level of the individual as well as encompassing issues of age, period, and cohort effects at the level of the community and population.

Placing the Individual in the Environment Theoretical approaches employed at the individual level that emphasize elements of personal control (e.g., theory of planned behavior, social cognitive theory) as critical to effective human function appear to have the most success in terms of identifying consistent correlates of physical activity. Critical to forging a strong sense of personal control in older adults is the provision of environments, social and emotional experiences, and motivational structures that are conducive to fostering such control.25 From a social cognitive perspective,2,26 several key determinants can be considered. For example, barriers to physical activity participation and accessibility of physical activity environments appear crucial to control beliefs. Ecologic approaches would be expected to reduce environmental barriers to participation in physical activity, improve accessibility of environments, and thereby potentially enhance control beliefs relative to physical activity. At the individual level, such beliefs are often operationalized as self-efficacy or expectations relative to confidence in one’s capabilities to successfully carry out courses of action.26 Efficacy expectations influence the types of behavior that we engage in, the degree of effort exerted, and the extent to which one perseveres in the face of failure or aversive stimuli. Efficacy expectations are perhaps the most frequently cited individual correlate of physical activity participation across populations.27,28 Moreover, success has been reported in the employment of efficacy-based interventions to enhance activity rates.29 Increased environmental physical activity opportunities should give

rise, in part, to enhanced self-efficacy, assuming, of course, that the individual possesses the appropriate skills to carry out the behaviors facilitated by such opportunities. It is important, however, to recognize that self-efficacy does not always influence behavior. Indeed, conscious cognitive processing is not always required for engagement in behavioral repertoires. That is, efficacy expectations typically influence behavior under challenging circumstances when sufficient skills and motivation are present.2 Engagement in physical activity for sedentary older adults is certainly a challenge, and self-efficacy would be expected to be predictive of behavior.30 However, once one has engaged in several months of continuous activity, the behavior begins to become part of one’s behavioral set. Thus, efficacy, while being maintained at a high level, is less responsible for the variability in exercise participation.30 Bandura26 suggests that upper-level (cognitive) control systems come into play in the face of challenging circumstances, whereas lower-control systems (habit) take over when the challenge is minimal. In a similar vein, self-efficacy beliefs appear to be particularly important in the understanding of functional limitations and disability. For example, Rejeski et al.31 reported self-efficacy to predict functional decline across time, but only in those with compromised function at baseline. The extent to which built environments can be made conducive to reducing the challenge of physical activity participation for older adults remains an important avenue of exploration (e.g., providing handrails in hallways in older adult residences to facilitate walking in those with compromised function). A recent study at the individual level has specifically compared the utility of cognitive and social factors associated with physical activity interventions in older adults. Brassington et al.32 came to the conclusion that whereas changes in self-efficacy and outcome expectations over a 6-month period were significantly associated with exercise participation in the subsequent 6 months, changes in social support were not. Although there may be several explanations for this latter finding (e.g., limitations of the social support measure), a social cognitive perspective would view social support influences on behavior as being indirect through the mediation of self-efficacy.33,34 Indeed, past exercise behavior has been shown to enhance levels of social support and increase levels of affect experienced during activity, and all three are predictive of subsequent self-efficacy.34 Such findings suggest support for the theorized sources of efficacy information and a more complex interplay of behavioral determinants than is often considered. Thus, ignoring social support within the exercise context may serve to reduce the total effect that self-efficacy is capable of having on exercise behavior. Although social support is frequently documented as a correlate of physical activity, this relationship has been evident largely in cross-sectional studies with few proAm J Prev Med 2003;25(3Sii)

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spective studies supporting this relationship.35–37 Moreover, difficulties exist with making consensus statements about the nature of the social support–physical activity relationship due to the variability in the measures and definitions employed across studies. Such an interplay among personal constructs, behavior, and the immediate environment led King et al.18 to characterize social cognitive approaches as individual plus microenvironmental models of physical activity participation. It will be important in the future to effectively articulate how ecologic interventions and such individual plus microenvironmental models are best integrated to effectively enhance known correlates of activity and subsequent physical activity behavior. Whereas social cognitive theory26 is typically employed to understand individual behavior, it can also be extended to the collective agency. The shaping and structuring of the environment and social institutions to enhance health-related behaviors, such as physical activity, might be theorized to result in perceptions of collective efficacy. These group level properties represent collective beliefs relative to the community’s capability to be physically active rather than an aggregate of beliefs at the individual level.3 Bandura38 presents evidence to indicate that enhanced self-efficacy at the group level leads to loftier goals, increased perseverance in the face of failure or difficulties, and greater performance. Although it is clear that the everyday activities of individuals may reinforce or modify “what and how things are done” in particular locales, the collective efficacy of the community group may bring about greater behavioral change at this level. The extent to which an ecologic approach to promoting physical activity operates through perceptions of efficacy at the group and individual level warrants examination. Along those lines, the relationship between selfefficacy and social capital may represent an important link in a transdisciplinary theory. This link may help to elucidate the interaction between the individual and the broader social and physical environment. Social capital is defined as “those features of social structures—such as levels of interpersonal trust and norms of reciprocity and mutual aid—which act as resources for individuals and facilitate collective action.”39 In fact, communities with higher levels of social capital may provide greater “opportunity structures,” such as attractive and safe places to walk for people to engage in particular activities.40 Social capital has typically been measured in a variety of ways, such as number of voters, number of voluntary associations, or reports of customs or “norms of reciprocity” in neighborhoods. There is evidence to suggest that residents of neighborhoods or communities with higher levels of social capital have more positive health outcomes than residents of areas with lower social capital. It is presently unknown, however, to what extent social capital affects health 188

through the development and maintenance of selfefficacy and to what extent social capital operates directly on healthful behaviors, such as physical activity. It also would be useful to determine whether social capital is reflected and, in turn, sustained by characteristics of the built environment, such as multiuse, highdensity housing, the presence of walkways, and “front porches” that encourage interaction. Finally, a fascinating issue concerns the extent to which collective acts of individual self-efficacy affect the level of social capital over time. This may take several forms. Individuals may be sufficiently motivated and confident to inspire and convince others in their neighborhoods and communities by word or deed to engage in physical activity. This, in turn, may help to establish new community norms or serve to reinforce existing norms of community activity. Specific individuals also may take the lead in empowering others to change the physical environment or public policy, such as the construction of a new public park or the installation of new pedestrian crosswalks, to enhance the confidence of community residents to engage in physical activities. In general, research on the health effects of social capital is promising but, as yet, is in the early stages of development. It also should be noted that there is a growing debate about the conceptual clarity and measurement criteria of social capital and whether the concept, in fact, is useful or only serves to obscure the health and behavioral effects of socioeconomic status.41,42 These points should be kept in mind as part of a more detailed consideration of the possible link between self-efficacy and social capital and the potential utility of that link for clarifying the relationship between the individual and the larger community.

Social Biology and Transdisciplinary Theory There is a growing body of research that examines the biological mechanisms and, in particular, the neuroendocrine pathways, between social behavior and health.42 This literature, sometimes referred to as “social biology,” may inform the development of a transdisciplinary theory and help to explain patterns of physical activity and the relationship of those patterns to the disablement process.43– 45 In particular, allostasis, the physiological capacity to successfully adapt to environmental challenges, and allostatic load, the cumulative biological burden exacted on the body through attempts to adapt to life’s demands, may represent parsimonious biological concepts that may explain patterns of physical activity and disablement.45 There is recent evidence that summary measures of allostatic load are significant predictors of cardiovascular mortality and decline in cognitive and physical functioning.46,47 There is also evidence that social support is inversely related to allostatic load.48 Allostatic load,

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then, may represent a useful summary measure of the physiologic components of transdisciplinary theory.

Establishment of Better Measures The development and application of this new theoretical approach depends on establishment of better measures. We see three primary issues of importance here: measurement of physical activity that addresses the interaction of the individual and the environment, strategies that capture social interaction more directly, and measurement of the physical environment. Measures of physical activity. Traditional measures of physical activity are typically based on questions that ask respondents to indicate mode, frequency, duration, and intensity level of activity. From this information, it is possible to calculate an overall level of physical activity, often represented by energy expenditure expressed in metabolic equivalent units (MET values). Although such measures are very useful, it is necessary to have additional information about the circumstances of the physical activity. In addition to these standard questions, it would be useful to ask when, where, and with whom an individual engages in physical activity. This information will place an individual’s physical activity into a broader social and environmental context. Additional questions could address the extent to which the individual limits and avoids physical activity and whether such limitations are moderated by the social context of the activity setting, such as the presence or absence of an exercise companion. Measures of social interaction. It is also necessary to develop strategies to examine social interaction more directly by including social groups, such as families, households, and neighborhoods, as the units of investigation. This approach would entail identifying and interviewing everyone in the social group. For example, in a household study, it would involve identifying and interviewing everyone in a household, such as marital partners and other household members. Beyond the home, it may require the use of snowball sampling. This is achieved by conducting interviews with an initial sample of people and then determining the name and location of key members of their social network. The next wave of interviews would be conducted with members of that network, and so on. Rather than relying on one person to report on another person’s level of physical activity, this network analysis provides an opportunity to collect information directly from each member of the social network.49 This strategy, in turn, would afford an opportunity to determine directly to what extent the level of physical activity of one person is associated with the level of physical activity of another. Moreover, this type of strategy lends itself to an examination of how a person’s level of health and functioning affects the level of physical activity in his or

her spouse or partner and how the nature of that interaction may vary over time. For example, there is evidence from a study of older spouse pairs in Sonoma, California, that the single best predictor of a person’s level of leisure-time physical activity is the level of leisure-time physical activity of that person’s spouse.50 Although the burden experienced by older family caregivers might act as a deterrent to physical activity participation, a first-generation study by King and Brassington51 reports on the success of a home-based program for improving physical activity participation in this population. Additionally, they found strong relationships between changes in a subject’s burden and changes in self-efficacy brought about by physical activity. Measures of environment. Measurements of the physical and built environments are figuring more prominently in epidemiologic and social science studies. Questions about the physical environment are increasingly included in personal interviews. First, in some studies, participants are asked to describe different aspects of their environment. For example, in the Women’s Health and Aging Study,52 participants are asked to report whether sleeping, bathroom, and food preparation accommodations are found on the first floor. This is very important as functional limitations may make stairs more difficult to navigate with increasing age. Second, participants may be asked to report their reactions to characteristics of their physical environment. For example, participants in the Alameda County Study and the Study of Physical Activity and Age-Related Changes in Sonomans (SPAARCS) are asked to report to what extent they experienced particular types of problems in their neighborhoods, such as poor lighting, broken sidewalks, heavy traffic, and speeding cars.16,53 Third, there is a growing body of research in community-based studies that include the identification and location of community assets as well as community needs, an important objective in the study of ethnically and socioeconomically diverse communities. Assets might include the presence and location of neighborhood parks, grocery stores, and community-based organizations. In contrast, needs or problems might include the presence and location of abandoned buildings and busy intersections, that is, potential markers for barriers to participation in physical activity in public settings. The development of comprehensive measures of the built environment will require drawing on the tools of a variety of different disciplines, including city planning and architecture, as well as social sciences and public health.54 –57 This should not be interpreted as a recommendation for the wholesale acquisition of the methods of one discipline for the purpose of applying them uncritically to solve the research problems of another. Although city planners and architects have developed methods to concepAm J Prev Med 2003;25(3Sii)

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tualize and summarize the characteristics of the physical and built environments, researchers must consider very carefully how those concepts and methods will improve our understanding of the extent to which environmental factors either impede or enhance levels of physical activity. In other words, we need to be able to specify the hypothesized mechanisms that may potentially explain associations between measures of the physical and built environment on the one hand and levels of physical activity on the other. Although these measures of the physical environment may contribute to the development and administration of an ecologic approach, there are other areas that need attention. For example, there is little information, as Carp58 noted, about how people, in fact, act in or use their environment. While a person may live near a walking trail, what is the frequency and manner in which that trail is used? In one of the few studies in this area, a video camera was used to assess how subjects with a mobility limitation managed physical barriers in the environment, compared to subjects without a limitation.59 In addition, while longitudinal studies capture changes in individuals and populations of people, in most cases, the characteristics of the physical environment, typically assessed at baseline, are held constant. New measures are needed to capture changes in the physical environment. In calling for new approaches to the measurement of key variables in an ecologic model of physical activity, we are also conscious of the need to refine our methods of analysis. For example, in recommending assessments at multiple levels (e.g., the individual, schools, communities, etc.), there will be a need to employ multilevel modeling that will allow for the simultaneous analysis of group- and individual-level effects on individual behavior.60 As we propose that the variable of time should be an integral part of such models, it will be necessary to examine the growth and form of changes in behavior over time using approaches such as latent growth curve modeling.61

Development and Evaluation of Strategies for the “Translation” of Research into Practice The development of new transdisciplinary theories holds the potential promise for theoretical improvements for guiding the development of a range of possible programs and policies into practice. There is the possibility of determining to what extent the relative success of programs directed at individuals is affected by characteristics of the broader environment, such as the “walkability” of neighborhoods, the number and location of parks and other places of recreation, and automobile volume and traffic flow. This issue will be of particular interest with regard to the sustaining of changes in physical activity among residents in different communities. Additionally, identifying which of these 190

characteristics has the greatest potential for influencing self-efficacy at the individual and collective level will allow strategists at all levels (e.g., community, local government, schools) to structure the environment accordingly. Future multisite, clinical trials may include subjects drawn from communities that differ with regard to measures of walkability or other activity-friendly indicators. This will provide an opportunity to determine whether the results of the trial vary by community context. One of the interesting challenges is directing and monitoring change at the policy level in the community. To our knowledge, the only age-based policies that deal explicitly with physical activity are those policies that prescribe levels of physical education for children in grades K–12. Although there are most certainly guidelines that have been provided by national bodies relative to types and prescriptions of physical activity for older populations, there are seemingly no policies that address physical activity in this group. In fact, it seems advisable that programs and policies in this area should not be presented as only benefiting older residents. The more policies are viewed as benefiting various groups in the community, the more likely that those policies will be instituted. Moreover, instituting policies across the community is more in keeping with a lifespan approach to health and well-being and is likely to encourage good health practices across the life course. Pedestrian safety, a policy area with indirect implications for physical activity, is an example of a policy objective that affects residents regardless of age.62 Finally, the establishment of environmentally based programs to enhance physical activity, such as walking, will require the establishment of new alliances. For example, there are professional and community groups working to reduce air pollution and urban sprawl through modification of existing zoning and housing regulations. Those groups have proposed the development of more pedestrian-oriented communities, characterized by the clustering of homes with goods and services (i.e., walkable, multiuse, high-density communities).63 Although the promotion of the public’s health is not the main objective of such programs, often referred to as the “New Urbanism,” they may have that effect.63

Training of a New Generation of Scholars The successful development of a programmatic agenda in this area may require training a new generation of researchers and practitioners. At the graduate or professional level, these students should be recruited from a variety of disciplines that could include, but would not be limited to, gerontology, geriatrics, kinesiology, epidemiology, the social and behavioral sciences, urban geography, environmental design and planning, architecture, and traffic engineering. The specific content of

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the curriculum of such a program, of course, would depend on the academic degree objective. At the doctoral and postdoctoral levels, this program could include training in study design and methods across a variety of disciplines. One model for a program of this kind is the newly established Robert Wood Johnson Foundation (RWJF) Scholars Program in Health and Society.64 This program is designed to train postdoctoral scholars in the developing field of population health. Based generally on an ecologic model, the program expects students to become conversant with the perspective and basic methods of a least one other discipline and to use that new information in conjunction with the perspective of his or her parent discipline to address a problem in population health. The RWJF program is also designed to train scholars in translational research, a critical instructional area for the development of a practice agenda in physical activity, aging, and health promotion. Finally, following from the RWJF program, it will be important for students to develop the facility to identify the health and nonhealth impact of programs and policies conceived and implemented for reasons other than either the promotion of physical activity or the maintenance of health and functioning in older populations.

Concluding Statements The promotion of physical activity in older populations holds the promise of promoting health and reducing the risk of disablement. There is a need to develop a variety of approaches to achieve that end. Although the programs that focus on the individual are important, they have had minimal success in sustaining changes in activity and preventing disability. Indeed, it may be argued that there has been little examination of how or if they are related to disability. The ecologic model fosters a more comprehensive agenda based on biological, behavioral, and environmental factors. There are clearly challenges associated with the development and administration of such a model. These challenges include the development of new theories and measures, the translation of research into practice and practice into research, and perhaps the recruitment and education of a new generation of researchers and practitioners. However, it is of paramount importance that we continue to realize that the interaction of the individual with the environment is as important and potentially more important than studying the role of the individual or the environment alone in the promotion of physical activity in older adults.

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