A nationwide study reveals that moving to a more walkable city can significantly increase daily steps and moderate-to-vigorous exercise, underscoring the role of urban design in enhancing public health. Conducted by researchers from the University of Washington and Stanford University, the study highlights how changes in the built environment can impact physical activity, using comprehensive data from across the United States.
Published in the journal Nature, the research found that relocating to walkable cities resulted in sustained increases in daily steps for at least three months across most age and gender groups. However, the increase was not statistically significant for women over 50 years of age.
Understanding the Study’s Context
The study’s findings mirror a global concern: physical inactivity contributes to major non-communicable diseases like cancer, diabetes, and cardiovascular disease. With rapid urbanization expected to result in most people living in cities by 2050, urban design’s impact on public health becomes increasingly crucial.
Previous research has linked the built environment, particularly walkability, to physical activity, but findings have been inconsistent. A major challenge has been determining whether increased activity levels are due to environmental factors or personal preferences for active living.
Many past studies faced limitations such as small sample sizes, limited geographic coverage, and reliance on self-reported data, which can be biased. The use of cross-sectional study designs also hindered causal inference. However, the advent of smartphones enables continuous, objective recording of both location and physical activity, allowing for large-scale, real-world analyses.
Insights from the Study
The research team analyzed nearly 250,000 days of step-count data from 5,424 U.S. users of a smartphone app, who moved at least once over three years, resulting in 7,447 moves between more than 1,600 cities. Step counts were recorded via smartphone accelerometers, validated for accuracy in both lab and real-world settings.
Physical activity was measured for up to three months before and after each move, creating a large-scale natural experiment. The study quantified how changes in walkability influence physical activity at both population and individual levels, using a vast smartphone-derived dataset to separate environmental effects from individual preferences.
Relocating to more walkable cities increased daily steps by approximately 1,100 steps per day, translating to about 11 extra minutes of walking.
Key Findings
Climate differences did not affect the outcomes. Moves between cities with similar weather patterns still resulted in expected step changes linked purely to walkability differences. The study found that relocating to more walkable cities significantly increased daily steps, while moves to less walkable areas produced equivalent decreases.
The effects were consistent across seasons, climates, and income levels. Census data indicated that most moves were for family, work, or housing reasons, not walkability, reducing self-selection concerns. The step increases were largely due to gains in moderate-to-vigorous physical activity (MVPA), defined as activity at a cadence of at least 100 steps per minute.
Large walkability improvements added roughly 1 hour of MVPA per week, nearly doubling the proportion of participants meeting U.S. aerobic activity guidelines from 21.5% to 42.5%.
Challenges and Considerations
Despite the positive outcomes, older women faced unique hurdles. While most groups saw clear benefits, women over 50 did not show significant increases, possibly due to factors like caregiving demands, wayfinding difficulties, and poor public transit access for non-commuters.
Simulation models estimated that raising all U.S. locations to the walkability level of cities like Chicago or Philadelphia could result in 36 million more Americans meeting activity guidelines, with even greater increases if matched to New York City’s level.
Conclusions and Implications
The study’s strengths include its large, diverse dataset, longitudinal design, and objective step measurement. The findings address common limitations in past research, such as small samples and reliance on self-reported data. Evidence against residential self-selection strengthens but does not prove causal interpretation.
However, the study has limitations, including potential bias toward higher socioeconomic status participants, restriction to U.S. cities, and reliance on city-level walkability scores, which obscure neighborhood-level variation. The method also misses non-step-based activities and requires participants to carry their phones for data capture.
The findings have strong policy implications, suggesting that improving walkability could substantially boost population-level physical activity. While achieving the walkability of highly walkable cities everywhere is unrealistic, targeted changes to urban design could yield significant health benefits, particularly if combined with age- and gender-specific strategies for groups like older women, who may face additional barriers to activity.
