April 2006

Grant Results

SUMMARY

The Transportation Research Board and the Institute of Medicine formed a 14-member committee to examine the connection between the built environment and the physical activity levels of the U.S. population.

Key Findings

  • Physical activity levels have declined sharply over the past half-century because of reduced physical demands of work, household management and travel together with increased sedentary uses of free time.
  • The built environment can facilitate or constrain physical activity. For example, ready access to parks and trails may facilitate walking for exercise; sidewalks and mixed-use development are likely to be more important to encourage walking to local shopping and for other utilitarian purposes.
  • The relationship between the built environment and physical activity is complex and operates through many mediating factors, such as sociodemographic characteristics, personal and cultural variables, safety and security and time allocation.
  • The available empirical evidence shows an association between the built environment and physical activity. However, investigators have conducted few studies capable of demonstrating a causal relationship, and evidence supporting such a relationship is currently sparse. In addition, the characteristics of the built environment most closely associated with physical activity remain to be determined.
  • Weaknesses of the current literature include the lack of a sound theoretical framework, inadequate research designs and incomplete data. Most of the studies conducted to date have been cross-sectional (research that looks at a single point in time). Longitudinal study designs using time-series data are also needed to investigate causal relationships between the built environment and physical activity.
  • The built environment in place today has been shaped by long-standing polices and the practices of many decision-makers. Many existing development patterns have resulted from zoning and land use ordinances, design guidelines and funding criteria for transportation infrastructure focused primarily on motorized transportation, values and preferences of homeowners and home buyers, and racial and economic concentration of the poor and disinvestments in their neighborhoods.

See Conclusions and Recommendations.

Funding
The Robert Wood Johnson Foundation (RWJF) provided $720,000 from September 2002 through April 2005 to support this solicited project.

 See Grant Detail & Contact Information
 Back to the Table of Contents


THE PROBLEM

During the past half-century or longer, major technological innovations — automation and the decline of physically active occupations, labor-saving devices in the home and the dominance of the automobile for personal travel — have substantially reduced the physical requirements of daily life.

In addition, the steady decentralization of metropolitan-area population and employment to widely dispersed suburban locations has increased travel distances to many destinations and made the private vehicle the most practical and convenient mode of transport.

Lifestyle and cultural changes, such as increases in television watching, have also played a role in reducing physical activity.

At the time of this project, the built environment had come under scrutiny as an important potential contributor to reduced levels of physical activity. Creating pedestrian-oriented environments that encourage people to walk or bike could significantly increase opportunities for routine daily activity.

 Back to the Table of Contents


RWJF STRATEGY

RWJF has been supporting ways to increase physical activity through design of the built environment and to build a stronger knowledge base from which to promote active living. Among RWJF's programs in this area are:

  • Active Living Research stimulates and supports research to identify environmental factors and policies that influence physical activity (for more information see Grant Results). Findings are expected to inform environmental and policy changes that will promote active living among Americans.
  • Active Living by Design incorporates activity-promoting goals and processes into ongoing community planning efforts and to support the development and testing of local community active living projects, with special efforts to reach low-income Americans.

 Back to the Table of Contents


THE PROJECT

With this grant from RWJF, the Transportation Research Board and the Institute of Medicine set out to examine the connection between the built environment and the physical activity levels of the U.S. population. The federal Centers for Disease Control and Prevention (CDC) provided $75,000 in support for this project.

The Transportation Research Board and the Institute of Medicine formed a committee of 14 experts in:

  • Transportation demand and travel behavior.
  • Land use planning and regulation.
  • Public health.
  • Physical activity and education.
  • Economics and public policy.
  • Safety
  • Social and behavioral science research and methods.

Susan Hanson, Ph.D., Landry University Professor and Director of the Graduate School of Geography at Clark University and a member of the National Academy of Sciences, chaired the committee. Bobbie Berkowitz, Ph.D., professor and chair of the Department of Psychosocial and Community Health at the University of Washington's School of Nursing and a member of the Institute of Medicine, served as vice chair. The committee met six times from January 2003 through August 2004.

To carry out its charge, the committee commissioned seven papers to explore various aspects of the relationships among land use, transportation and physical activity (see the Bibliography). The papers underwent extensive review and comment by the committee and were revised numerous times.

The committee also drew from a paper on the role of segregation and poverty in limiting choices for physical activity among disadvantaged populations, written by Benjamin P. Bowser, Ph.D., department of sociology and social services, California State University at Hayward.

The committee held a workshop on December 11, 2003, in Washington to involve a broader audience of experts drawn from academia, consulting firms, professional associations, advocacy groups, state and federal agencies, congressional staff and the press. The committee also supplemented its expertise by receiving briefings at its meetings from a wide range of experts.

The study committee produced a final report entitled Does the Built Environment Influence Physical Activity? Examining the Evidence. (See Findings, Conclusions and Recommendations for details.)

The report was released at a public briefing at the 2005 Transportation Research Board Annual Meeting held in Washington More than 150 people attended the briefing. Transportation Research Board staff also prepared and circulated a press release publicizing the release of the committee's report.

Committee members presented the findings in the report at a number of venues:

  • Bobbie Berkowitz, Ph.D., gave a talk on the report at Arizona State University.
  • Don Chen, Ph.D., presented the recommendations of the study at a congressionally sponsored policy briefing on Building Healthier Communities: How Neighborhood Design Can Encourage Healthy Lifestyles.
  • Patricia L. Mokhtarian, Ph.D., testified before a California Senate Committee on public health and the built environment.
  • Susan Hanson, Ph.D., committee chair) presented the study results at the second annual conference of RWJF's Active Living Research program.

 Back to the Table of Contents


FINDINGS

The committee reported its findings in the report Does the Built Environment Influence Physical Activity? Examining the Evidence:

  • Physical activity levels have declined sharply over the past half-century because of reduced physical demands of work, household management and travel, together with increased sedentary uses of free time. Labor-saving technological innovations have brought comfort, convenience and time for more leisure activities. They have also resulted in more sedentary lifestyles with adverse health affects for many Americans.
  • The built environment can facilitate or constrain physical activity. The built environment can be structured in ways that give people more or fewer opportunities and choices to be physically active. The characteristics of the built environment that facilitate or constrain physical activity may differ depending on the purpose of the activity. For example, ready access to parks and trails may facilitate walking for exercise; sidewalks and mixed-use development are likely to be more important to encourage walking for local shopping and other utilitarian purposes.
  • The relationship between the built environment and physical activity is complex and operates through many mediating factors, such as sociodemographic characteristics, personal and cultural variables, safety and security and time allocation.
    • Whether an individual is physically active is determined largely by his or her capacity, propensity and willingness to make time for physical activity. For example, while public health surveys have found that, on average, physical activity levels decline with age, many senior citizens remain physically active.
    • Individual behavior is also influenced by the social and physical environment. For example, the social disorder and deteriorated physical condition of many poor inner-city neighborhoods deter physical activity for many residents even though these neighborhoods have some of the physical characteristics thought to be conducive to walking and non-motorized transport, such as sidewalks and multiple destinations within close proximity.
  • The available empirical evidence shows an association between the built environment and physical activity. However, few studies capable of demonstrating a causal relationship have been conducted, and evidence supporting such a relationship is currently sparse. In addition, the characteristics of the built environment most closely associated with physical activity remain to be determined.
    • Preliminary research does provide some evidence suggesting that such factors as access, safety and security are important for some forms of physical activity, such as walking and cycling, and for some population groups.
    • However, the findings are not definitive because it is not known whether these characteristics affect a person's overall level of physical activity or just his or her amount of outdoor walking and cycling.
    • Furthermore, the literature has not established the degree of impact of the built environment and its various characteristics on physical activity levels; the variance by location (e.g., inner city, inner suburb, outer suburb) and population subgroup (e.g., children, the elderly, the disadvantaged); or the importance to total physical activity levels, the primary variable of interest from a public health perspective.
  • Weaknesses of the current literature include the lack of a sound theoretical framework, inadequate research designs and incomplete data. The current state of knowledge in this area is limited in part by the lack of a sound theoretical framework to guide empirical work and inadequate research designs.
    • Most of the studies conducted to date have been cross-sectional — research that looks at a single point in time.
    • Longitudinal study designs using time-series data are also needed to investigate causal relationships between the built environment and physical activity.
    • Studies that distinguish carefully between personal attitudes and choices and external influences on observed behavior are needed to determine how much an observed association between the built environment and physical activity — for example, in an activity-friendly neighborhood — reflects the physical characteristics of the neighborhood versus the lifestyle preferences of those who choose to live there.
    • Appropriate measures of the built environment are still being developed and efforts to link such measures to travel and health databases are at an early stage.
  • The built environment in place today has been shaped by long-standing polices and the practices of many decision-makers, such as policy-makers, elected officials, planners, developers and traffic engineers. Many existing development patterns have resulted from zoning and land use ordinances, design guidelines and funding criteria for transportation infrastructure focused primarily on motorized transportation, values and preferences of homeowners and home buyers (e.g., suburban lifestyles, single-family housing), and racial and economic concentration of the poor and disinvestments in their neighborhoods. At the same time, the built environment is constantly changing as homes are renovated and new residences, developments and office complexes are constructed.

 Back to the Table of Contents


CONCLUSIONS

The committee reported the following conclusions in its report Does the Built Environment Influence Physical Activity? Examining the Evidence:

  • Regular physical activity is important for health, and inadequate physical activity is a major, largely preventable public health problem. The committee concurs with the strong and well-established scientific evidence linking physical activity to health outcomes and supporting reversal of the decline in overall physical activity levels as a public health priority. The connection between regular physical activity and health, although not the primary focus of this study, has clearly motivated interest in examining the built environment as a potential point of intervention to encourage more active behavior.
  • Built environments that facilitate more active lifestyles and reduce barriers to physical activity are desirable because of the positive relationship between physical activity and health. Achieving this goal is challenging in a highly technological society with a built environment that is already in place and often expensive to change; nevertheless, even small increases in physical activity levels can have important health and economic benefits. Moreover, the built environment is constantly being renovated and rebuilt and new developments are being constructed; these changes provide opportunities to incorporate more activity-conducive environments. In the committee's judgment, such changes would be desirable even in the absence of the goal of increasing physical activity because of their positive social effects on neighborhood safety, sense of community and quality of life.
  • Continuing modifications to the built environment provide opportunities, over time, to institute policies and practices that support the provision of more activity-conducive environments. The long-term decline in physical activity among the U.S. population has been the cumulative result of many changes; thus, there are opportunities for intervention. However, some interventions will be easier to effect than others. For example, formidable hurdles would have to be overcome to substantially modify long-standing policies. One example is the current system of zoning regulations and land use controls, which reflects the preference of many suburban homeowners and buyers, to allow greater density of development and more mixed land use. Similarly, many barriers persist to ending concentrations of minority populations and underinvestment in poor neighborhoods and the accompanying social and economic isolation of the poor. More flexible and targeted approaches — such as context-sensitive design, special overlay districts, traffic calming measures and community policing — have a better chance of gaining support.
  • Opportunities to increase physical activity levels exist in many settings — at home, at work, at school, in travel and in leisure. The built environment has the potential to influence physical activity in each of these settings. Each setting is characterized by different environmental opportunities and constraints that could affect physical activity levels. In some neighborhoods, for example, residents walk for utilitarian purposes. Keeping those neighborhoods safe and providing desirable destinations should reinforce and perhaps enhance this behavior. In other neighborhoods, walking for utilitarian purposes is limited. In these settings, recreational walking and cycling may offer the greatest potential for increasing physical activity in the daily routine.
  • Many opportunities and potential policies exist that could change the built environment in ways that are more conducive to physical activity, but the available evidence is not sufficient to identify which specific changes would have the most impact on physical activity levels and health outcomes. Research has not yet identified causal relationships to a point that it would enable the committee to provide guidance about cost-beneficial investments or to state unequivocally that certain changes to the built environment would lead to more physical activity or be the most efficient ways of increasing such activity. Effective policies to this end are likely to differ for different population groups (children, youth, the elderly, the disadvantaged); for different purposes of physical activity (transportation, exercise); and in different contexts (inner city, inner suburb, outer suburb, rural).

Recommendations

The committee offered the following recommendations in its report Does the Built Environment Influence Physical Activity? Examining the Evidence:

  • Given the current state of knowledge and the importance of physical activity for health, the committee urges a continuing and well-supported research effort in this area, which Congress should include in its authorization of research funding for health, physical activity, transportation, planning and other related areas. Priorities for this research include the following:
    • Interdisciplinary approaches and international collaboration bringing together the expertise of the public health, physical activity, urban planning and transportation research communities, among others, both in the United States and abroad.
    • More complete conceptual models that provide the basis for formulating testable hypotheses, suggesting the variables and relationships for analysis and interpreting the results.
    • Better research designs, particularly longitudinal studies that can begin to address causality issues, as well as designs that control more adequately for self-selection bias.
    • More detailed examination and matching of specific characteristics of the built environment with different types of physical activity to assess the strength of the relationship and the proportion of affected population subgroups. All types of physical activity should be included because there may be substitution among different types. The goal from a public health perspective is an increase in total physical activity levels.
  • National public health and travel surveys should be expanded to provide more detailed information about the locations of physical activity and travel, which is fundamental to understanding the link between the built environment and physical activity in all contexts.
  • When changes are made to the built environment — whether retrofitting existing environments or constructing new developments or communities — researchers should view such natural experiments as "demonstration" projects and analyze their impacts on physical activity.
  • Leadership of the U.S. Department of Health and Human Services and the U.S. Department of Transportation should work collaboratively through an interagency working group to shape an appropriate research agenda and develop a specific recommendation to Congress for a program of research with a defined mission and recommended budget.
  • Federally supported research funding should be targeted to high-payoff but difficult-to-finance multiyear projects and enhanced data collection.
  • The committee encourages the study of a combined strategy of social marketing and changes to the built environment as interventions to increase physical activity. The research should be designed to study these approaches both separately and in combination so that the influence of individual factors can be evaluated.
  • Universities should develop interdisciplinary education programs to train professionals in conducting the recommended research and prepare practitioners with appropriate skills at the intersection of physical activity, public health, transportation and urban planning.
  • Those responsible for modifications or additions to the built environment should facilitate access to, enhance the attractiveness of and ensure the safety and security of places where people can be physically active.

 Back to the Table of Contents


LESSONS LEARNED

  1. The project reinforced the desirability of an interdisciplinary approach to complex policy issues. In this case, the project brought together the public health/exercise science and transportation communities in a productive collaboration to review what is known about the role of transportation and land use on physical activity and health. (Project Manager)

 Back to the Table of Contents


AFTER THE GRANT

RWJF funded a team of researchers to plan a longitudinal study of the relationship between the built environment and physical activity. The study has been launched under RWJF's Synthesis Project and was still in process as of February 2006.

RWJF continues to fund studies in these areas through its Active Living Research program.

Since RWJF funded this project, the CDC has issued evidence-based guidelines for community-based design interventions that promote physical activity. They found strong evidence for the creation of and/or enhanced access to places for physical activity combined with informational outreach activities.

Senators Carl Levin (D-Mich.), Robert Bennett (R-Utah) and James Jeffords (I-Vt.) sponsored a congressional policy briefing entitled "Building Healthier Communities: How Neighborhood Design Can Encourage Healthy Lifestyles" on July 11, 2005, in Washington.

The National Association of Counties passed a resolution asking Congress to "significantly fund research and demonstration projects to encourage counties and localities to develop efficient land use planning and infrastructure design practices that are fiscally sensible and produce better physical activity and health outcomes."

 Back to the Table of Contents


GRANT DETAILS & CONTACT INFORMATION

Project

Evaluating the Links Among Physical Activity, Health, Transportation and Land Use

Grantee

National Academy of Sciences (Washington,  DC)

  • Amount: $ 720,000
    Dates: September 2002 to April 2005
    ID#:  045826

Contact

Nancy Humphrey
(202) 334-2948
nhumphrey@nas.edu

 Back to the Table of Contents


APPENDICES


Appendix 1

Glossary

Transportation Research Board serves the National Academy of Sciences and the National Academy of Engineering, which advise the federal government on scientific and engineering issues.

Institute of Medicine, also part of the National Academies, advises the federal government on medical care, research and education.

The built environment refers to physical environments that have been modified by people; it comprises public spaces, parks and trails as well as physical structures such as homes, schools and workplaces, and transportation infrastructure such as streets and sidewalks. It is broadly defined to include land use patterns, the transportation system and design features that together generate needs and provide opportunities for travel and physical activity.

 Back to the Table of Contents


BIBLIOGRAPHY

(Current as of date of this report; as provided by grantee organization; not verified by RWJF; items not available from RWJF.)

Commissioned Papers

The papers listed below are available online.

Boarnet MG. "The Built Environment and Physical Activity: Empirical Methods and Data Resources." Department of Urban and Regional Planning, University of California, Irvine, July 18, 2004.

Brownson RC and Boehmer TK. "Patterns and Trends in Physical Activity, Occupation, Transportation, Land Use, and Sedentary Behaviors."

Handy S. "Critical Assessment of the Literature on the Relationships Among Transportation, Land Use, and Physical Activity."

Kirby SD and Hollander M. "Consumer Preferences and Social Marketing Approaches to Physical Activity Behavior and Transportation and Land Use Choices."

Loukaitou-Sideris A. "Transportation, Land Use, and Physical Activity: Safety and Security Concerns."

Meyer MD and Dumbaugh E. "Institutional and Regulatory Factors Related to Nonmotorized Travel and Walkable Communities."

Sclar ED, Northridge ME and Karpel EM. "Promoting Interdisciplinary Curricula and Training in Transportation, Land Use, Physical Activity, and Health."

Reports

Does the Built Environment Influence Physical Activity? Examining the Evidence. Washington: Transportation Research Board and Institute of Medicine of the National Academies, 2005.

 Back to the Table of Contents


Report prepared by: Barbara Matacera Barr
Reviewed by: Richard Camer
Reviewed by: Molly McKaughan
Program Officer: C. Tracy Orleans