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Diabetes Special Issue |
AD Deshpande, PhD, MPH, is Research Assistant Professor, Division of Health Behavior Research, Washington University School of Medicine, 4444 Forest Park Ave, Box 8504, St Louis, MO 63108 (USA)
EA Dodson, PhD, MPH, is Program Manager, Prevention Research Center in St Louis, George Warren Brown School of Social Work, Washington University, St Louis, Missouri
I Gorman, PT, MSPH, is Assistant Professor, School of Physical Therapy, Rueckert-Hartman College for Health Professions, Regis University, Denver, Colorado
RC Brownson, PhD, is Professor of Epidemiology, Prevention Research Center in St Louis, George Warren Brown School of Social Work, Washington University, and Department of Surgery and Siteman Cancer Center, Washington University School of Medicine
Address all correspondence to Dr Deshpande at: adeshpan{at}dom.wustl.edu
Submitted January 24, 2008;
Accepted July 14, 2008
 | Abstract |
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| Introduction |
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Although there are multiple genetic and environmental factors that increase the risk for diabetes, recent epidemiologic research suggests that the worldwide epidemic rise in the incidence of diabetes over the past 2 decades is largely due to changes in lifestyle factors, such as diet and physical activity.12 It has been estimated that as much as 24% of the incidence of type 2 diabetes may be attributable to sedentary lifestyle.13 However, in the United States in 2005, more than half of all adults were not active at nationally recommended levels, and a full 14% were completely inactive.14 Additionally, the prevalence of physical inactivity increases with age and is higher among ethnic minority groups compared with whites within every age group.14 Although the focus on obesity and diet as preventable risk factors for diabetes has emerged only over the last decade or so, research on the role of physical activity in diabetes management and, more recently, in prevention of type 2 diabetes has a longer history.15,16 Additionally, there is growing evidence that environmental and policy approaches to increase physical activity may increase population levels of activity and, therefore, serve as a means to prevent the growing diabetes epidemic in the United States.
The objectives of this perspective article are: (1) to summarize the literature on the role of physical activity in the primary prevention of type 2 diabetes; (2) to discuss the importance of taking a socioecological or "multilevel" approach to increasing physical activity at the population level in the United States; (3) to discuss the unique role that state and local policy approaches can play to promote physical activity within the US population; and (4) to highlight multilevel, evidence-based strategies that physical therapists can use. A multilevel approach to increase population levels of physical activity holds promise to reduce the burden of type 2 diabetes in the United States.
| Evidence on the Role of Physical Activity for Diabetes Primary Prevention |
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The ability of regular participation in physical activity to help prevent diabetes is clearly established.18 Development of diabetes in populations with regular, habitual activity is relatively low.5 Numerous epidemiologic studies, using different designs and populations, support a causal association between regular physical activity and prevention of diabetes. There are currently published randomized controlled trials in different countries around the world that have shown that intensive interventions in lifestyle factors (diet and physical activity) are effective in delaying the onset or prevention of diabetes among individuals with impaired glucose tolerance.16,19–21 In each study, the study population comprised people with impaired glucose tolerance. Each study included at least one lifestyle intervention arm that involved individualized counseling or instruction on diet and exercise with more-frequent, intensive intervention early in the trial and follow-up sessions scheduled at longer intervals during the remainder of the trial. The studies varied to some degree in their specific intervention components and in overall effectiveness, but they consistently demonstrated that lifestyle modification, even with only modest weight reduction and moderate exercise, is effective in delaying or preventing the onset of diabetes in high-risk groups. Additionally, there is evidence that lifestyle modification interventions are more cost-effective per quality-adjusted life year than metformin or placebo.15 This may provide economic justification for the benefit of lifestyle modification over pharmaceutical approaches to prevention. Observational studies also have shown that physical inactivity is an independent risk factor for diabetes, even after adjustment for diet and obesity.13,22 There is additional evidence that as frequency and intensity of physical activity increase, the risk of incident diabetes decreases.23 A recent review of 10 prospective cohort studies indicated that people with an active lifestyle have an approximately 30% lower risk of diabetes than people who are inactive.24
There is growing evidence that it is not simply a lack of physical activity that increases the risk for diabetes. Sedentary behaviors, such as excessive television watching or prolonged computer use, also may play a role in elevating diabetes risk. Findings from the Nurses Health Study and the Health Professionals’ Follow-up Study indicate that as the number of hours of sedentary behavior increase per day or per week, the risk of diabetes increases independently of any reduction in physical activity.25,26
Although there are a growing number of observational studies showing that physical activity alone or in combination with other health behaviors can reduce the incidence of diabetes in high-risk groups, there are as yet no broad-based, population-level randomized trials of the role of physical activity on diabetes prevention.27 Additionally, it is unclear how intensive randomized trial interventions to increase physical activity and reduce the risk of incident diabetes among high-risk individuals in a medical setting can be translated into "real-world" settings, to high-risk individuals at the population level, or to lower-risk individuals.5
To date, intensive and effective diabetes prevention has been done at the level of the individual within the medical setting. This has resulted in a medicalization of health promotion, which translates to either secondary prevention approaches to screen for diabetes or tertiary prevention approaches to prevent complications among those already diagnosed with type 2 diabetes. This is due, at least in part, to the fact that preventive activities in the clinical setting are usually "opportunistic," often occurring during health care visits for other, often unrelated health issues. This is not surprising, given that as much as 95% of the US health care budget goes to direct medical care and services and only 5% goes to prevention activities.28 Primary prevention efforts are needed to prevent the disease from ever occurring. It has been suggested that "prevention of the disease is our only chance to alleviate the ever growing burden of diabetes mellitus in the world."29(p180)
A more broad-based, population-level approach to diabetes prevention is needed to lay a foundation for and support ongoing, individually focused prevention efforts. Additionally, intervention efforts that move away from targeting high-risk adults to facilitating behavioral change in the population as a whole (including low-risk adults, children, people with other conditions, and so on) are warranted.30–32 Such population-level approaches could shift the entire population curve for diabetes risk to the left.33
Numerous sociodemographic, psychosocial, environmental, and policy influences on physical activity behavior have been identified. Commonly reported barriers to physical activity include lack of time, lack of energy, no enjoyable scenery to look at, not observing others being physically active, and lack of access to facilities.34–36 Among older adults, the barriers are somewhat different and include the presence of health problems or general poor health, lack of counseling by a physician, lack of access to facilities, and low knowledge of the role of physical activity in disease prevention.37 Within the past decade, characteristics of the social environment (eg, safety from crime or traffic, trust in community members) and the physical environment (eg, the presence of parks or walking trails, maintained sidewalks in the neighborhood) have been shown across the world to be important influences on physical activity.38–40 To promote health, therefore, the environment in which people live must offer economic and social conditions conducive to healthy lifestyles.38,40,41 Effective interventions are currently available for the promotion of physical activity.42–44 They range from psychosocial interventions to environmental changes and can be supported and implemented by health care professionals.
| A Framework for Increasing Physical Activity at the Population Level |
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Active living can be accomplished in numerous ways within different domains of life. These may include walking or bicycling to work or school, engaging in occupational activity in the workplace, doing household or yard activities, or engaging in recreational walking. This active living approach to physical activity seeks to increase activity in the daily lives of most children and adults in the population and provides more opportunities for effective interventions within various settings (eg, home, school, workplace, community, medical settings) to effect that change. Sallis and colleagues47 proposed that multilevel interventions to increase physical activity must be based on the socioecological model (a conceptual framework developed by McLeroy et al48 suggesting that behavior is determined by the interaction between an individual and his or her environment). In this multilevel framework of active living, intervention targets focus on individuals as well as the physical environment, the social environment, and public policies. The authors contend that such multilevel, socioecological-based approaches are necessarily transdisciplinary (ie, bringing together health care providers, health educators, urban planners, parks and recreations officials, transportation officials, policy makers, and many others) and occur within numerous traditional settings (eg, medical settings, schools, workplaces, communities).47 The proposed socioecological framework describes the intrapersonal and environmental determinants of active living (Figure). This framework of active living reflects the interrelationship among the different structural layers, from individual-level characteristics (eg, age, sex) to environmental factors (eg, perception of the environment, access to facilities) to large-scale, sociopolitical forces (eg, land-use policies, transportation policies).
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| The Importance of Working at the Policy and Institutional Levels |
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For promotion of physical activity, there is an important nexus between policies and the physical or "built" environment. Increasingly, links are being identified between various elements of the built environment and rates of physical activity.38,42,49 The built environment, the physical form of communities, consists of 2 key elements: land-use patterns (ie, the location of activities across space) and the transportation system (ie, the facilities and services that link one location to another).50,51 Each of these elements is strongly influenced by local, state, and federal policies.
| Characteristics of Policies and the Policy Process |
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Although the term "policy" may lead people to think of mandates or legislative actions, it is critical to note that a policy need not be a federal or state law. Schmid and colleagues defined policy as a "legislative or regulatory action taken by federal, state, city, or local governments, government agencies, or nongovernmental organizations such as schools or corporations."52(pS22) Furthermore, they explained that policies can range from formal written codes (eg, legislation) to unwritten social norms that influence behavior (eg, highway patrol's frequent allowance of a few miles per hour above posted speed limits). Thus, when considering policy interventions to increase physical activity and reduce diabetes, one should not neglect the power of these "de facto" policies.
The policy itself and the policy process are both important.59 Kingdon59 argued that policies move forward when elements of 3 "streams" come together. The first stream is the definition of the problem (eg, a high diabetes rate). The second stream is the development of potential policies to solve that problem (eg, identification of policy measures to achieve an effective diabetes prevention strategy). Finally, there is the role of politics and public opinion (eg, interest groups supporting or opposing the policy). Policy change occurs when a "window of opportunity" opens and the 3 streams push policy change through.59
Interventions and policy changes have tremendous potential to succeed in schools and work sites because of the tools, resources, networks, infrastructure, and staff that already exist. This allows interventions to be implemented in these settings more efficiently, as much of the initial development work can be eliminated or reduced prior to implementation. Typical interventions that have been tried at schools and work sites primarily include information exchanges. For example, work sites frequently have promotional activities, educational programs, health fairs, or one-time risk assessments.60 Similarly, schools often implement programs that involve teacher-led, classroom-based educational programs or sending newsletters home to parents.60 Although these may be helpful means to communicate information, sufficient public health research has shown that information alone is not enough to change individual behaviors in most cases.61
Policy interventions, by comparison, are able to create systems change.54,62 They can be designed to provide opportunities, support, and cues to help people develop healthier behaviors. Policy interventions have the potential for broad population impact and, therefore, can positively, simultaneously, and cost-effectively influence entire populations. Additionally, policy interventions can indirectly affect behaviors or social norms,54 and they often are farther reaching and more enduring than those focused on changing individual behavior.63 Finally, policy interventions can be highly cost-effective.54 One of the best public health examples of the use of a multilevel, policy-oriented approach to influence behavior is the decades-long, population-level intervention to reduce smoking in the US population.54 Public health efforts over the past several decades to reduce smoking behavior in the United States have taught researchers and practitioners about the multiple influences and opportunities for intervention at different levels of the socioecological framework. This ultimately demonstrated the powerful impact that policy change (eg, indoor smoking restrictions, increasing taxes on cigarettes, regulations on marketing strategies) can have on social norms, environment, and, most importantly, behavior. We can now use lessons learned from the public health effort to reduce smoking rates in the United States to inform policy-oriented strategies to increase population rates of physical activity.
| Evidence-Based Policy Interventions |
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By way of example, in the Table we describe specific evidence-based policy approaches that could be introduced in schools, work sites, and communities to increase physical activity behavior.42,44,54 The intervention categories or domains and the evidence that specific strategies within these categories lead to increased levels of physical activity are based on numerous studies in different countries and settings.54 The findings presented in the Table are adapted from a review article by Brownson and colleagues,54 which summarized environmental and policy interventions to prevent chronic diseases. These policy interventions ranged in complexity and cost from relatively simple, low-cost, point-of-decision prompts to more-complex, high-cost urban planning and policy interventions. Interventions were graded on effectiveness based on systematic reviews from the Community Guide43,44 and narrative reviews. In the next section, we discuss the value of targeting policy approaches to different settings (eg, home, school, workplace) and provide examples of different policies that might be relevant within different settings.
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| Targeting Policy Approaches Within Different Settings |
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Studies conducted at work sites and schools offer excellent evidence-based solutions for promoting health at these sites. For example, work-site stairways should be made safe and accessible to employees and, if possible, should be attractive and well-lit.65,66 Employees should be offered incentives for walking or biking to work and should be given time or breaks during the day for physical activity.66,67 Other ideas could include offering reserved parking spaces or other incentives to employees willing to park far away from their building. It is exceptional when treadmills, weights, gyms, lockers, and showers are available for employees at work sites; however, when employers are not able to offer facilities or equipment for physical activity on-site, employees could receive subsidies on health club memberships.53
Policies that promote and protect specific opportunities for physical activity during the school day may increase physical activity behavior among youth. Junior high and high school daily schedules should include at least 30 minutes for physical activity and should include options for noncompetitive types of activity such as aerobics and dance. Furthermore, grade schools should ensure adequate recess time and space for children to be active.53,60 These suggestions represent only a few ways that policy changes can be implemented to create school and work-site environments that facilitate healthy choices and behaviors, thereby increasing the likelihood that individuals will prevent overweight, obesity, and diabetes. In the next section, we describe the opportunities for and potential roles of physical therapists in initiating, implementing, and evaluating physical activity policies within different settings, thereby supporting the primary prevention of type 2 diabetes in the population.
| Physical Therapists and Diabetes Prevention |
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Traditional Role of Physical Therapists
Because the relationship between policy and diabetes is mediated by physical activity and obesity,71 physical therapists are well-prepared to apply their physical activity expertise to advocate for policy change. However, as a clinical health profession, physical therapy traditionally focuses on individuals rather than at the population level. The Guide to Physical Therapist Practice72 describes the 3 levels of prevention (ie, primary, secondary, and tertiary); however, in its discussion of the 5 elements of patient management, it focuses primarily on individually based interventions. Furthermore, although primary prevention is a part of the preferred practice patterns,73 these recommendations generally address patient/client risk reduction, based on an evaluation of examination data, rather than risk reduction in individuals who are asymptomatic for the disease.72
Interestingly, such activities do not fit the definition of primary prevention used in public health and discussed previously. When physical therapists engage in prevention activities, it is commonly either secondary prevention (eg, screening high-risk individuals for disease or risk factors) or tertiary prevention (eg, provision of rehabilitation).74,75 A recent review examining health promotion and physical therapy found few publications and no systemic reviews linking physical therapist practice with primary prevention and health promotion.76 According to the review, the most commonly used health promotion strategy in physical therapist practice is health education at the individual level. It is perhaps because physical therapy is rooted in the biomedical model that the definitions of primary prevention and health promotion differ from those used in public health.76 Thus, we propose a conceptual shift in physical therapists’ understanding of primary prevention as they seek to prevent diabetes through physical activity promotion.
Recommendations for an Expanded Role for Physical Therapists
There are many ways and a variety of settings beyond clinics in which physical therapists can be involved in the primary prevention of diabetes (Table). For example, physical therapists can offer school-based consultation and expertise to assist physical education teachers, school nurses, and other health promotion professionals to design and implement safe and effective physical activity programs and health education. As health care professionals in the community, physical therapists can apply their expertise in movement and exercise to help lobby school officials and administrators to increase the amount of physical education and recess time scheduled during the school day. Such work is already ongoing through pilot projects in some Colorado schools, where physical therapist students and faculty partner with teachers to educate students and encourage increased physical activity during the school day.
At work sites, physical therapists can serve as experts in wellness programs that offer screenings and exercise prescriptions to employees.68 Additional areas of involvement could include offering support and encouragement for primary prevention activities such as the design and promotion of safe walking areas (stairwells, paths) in work-site settings, initiating pedometer programs and work-site competitions, or organizing group activities (daily walks). Research shows that even simple interventions, such as placing signage near elevators and escalators to promote stair use, have led to an increase in stair use.44
Physical therapists also can intervene through community-based activities, such as offering assistance in street and park design, encouraging patients to visit recreation centers, and organizing community activities to encourage safe and effective physical activity (eg, running/biking races). Additionally, October is National Physical Therapy Month, during which many clinics and professionals offer education and health promotion materials at athletic and sporting venues, senior centers, and schools throughout the community. These examples represent excellent opportunities for physical therapists to promote physical activity in local schools, work sites, and communities.
Physical therapists enjoy a unique and positive relationship with their patients and the community, largely because of their ability to spend focused, one-on-one time with them while instilling confidence and enhancing positive outcomes through their communication.77,78 A recent American Physical Therapy Association (APTA) marketing study on "PT branding" demonstrated that nearly 90% of all consumers studied have a positive impression of physical therapists.79 Thus, physical therapists have an excellent opportunity to promote advocacy by encouraging patients to contact local, state, and federal legislators and other policy makers about creating environmental or policy changes that encourage physical activity in schools, workplaces, and their communities. Advocacy can range from raising awareness of an issue to communication of research results to policy makers to actively lobbying for a particular policy. Although health care providers can directly offer information and expertise to policy makers, it is often a story from a patient that really moves policy makers to action.80 Physical therapists can promote these activities. A new position statement recently adopted by the APTA House of Delegates supports the role of physical therapists and physical therapist assistants in promoting the benefits of physical activity and encourages physical therapy professionals to "provide leadership in supporting scientific, educational, and legislative activities directed to the promotion of regular physical activity/exercise in order to enhance health and prevent disease."81
| Conclusions |
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It is becoming increasingly clear that broad-based, multilevel, evidence-based policy interventions are needed to increase population levels of physical activity. These efforts must be sensitive to the contextual conditions in communities in which they occur (eg, sociopolitical forces). It also is becoming increasingly clear that policy-based, multilevel approaches to the prevention of type 2 diabetes are needed. It has even been suggested that "prevention of the disease is our only chance to alleviate the ever-growing burden of diabetes mellitus in the world."29(p180) Physical therapists are in a unique and influential position in which they can not only promote physical activity directly with patients in clinical settings but also play an important role in shaping the policy environments in their communities in ways that promote physical activity and ultimately reduce the incidence of diabetes at the population level.
| Footnotes |
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This work was supported, in part, by Centers for Disease Control and Prevention (CDC) contract U48/DP000060 (Prevention Research Centers Program) and CDC grant 5R18DP001139–02.
| References |
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
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Introduction
Evidence on the Role...