People who moved to cities with better walkability logged about 1,100 more steps per day and were nearly twice as likely to meet exercise goals, according to a large U.S. relocation study published in the journal Nature on Wednesday.
Researchers from the University of Washington and Stanford University tracked about 5,500 Americans of all ages and fitness levels as they moved between 1,600 U.S. cities, monitoring their activity for 90 days before and after the move, from 2013 to 2016.
Using smartphone step counts and the Walk Score system, which rates locations from 0 to 100 based on access to amenities like stores, parks and schools, they found that moving from a low-walkability city (48 or less) to a high-walkability one (75 or more) added an average of 1,100 steps a day.
That equated to roughly 11 extra minutes of walking per day, or about one additional hour of moderate-to-vigorous physical activity per week.
The biggest jump came from moves to places like New York City, where a Walk Score of 89 translated to daily steps climbing from about 5,600 to 7,000.
"We were positively surprised by the size of that effect," Tim Althoff, the lead author of the study and an associate professor at the University of Washington in the Paul G. Allen School of Computer Science & Engineering, said. "On average, people walked about 1,400 steps every day more when they moved to New York, or if they moved [in] the opposite direction, they lost about 1,400 steps a day."
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However, Althoff noted that not all steps are created equal.
"Most of the difference actually was in this kind of brisk walk regime that is considered moderate or above," he said.
In those who moved from low- to high-walkability cities, the proportion who met the U.S. physical activity guidelines increased from 21.5% before relocation to 42.5% after relocation. Many also moved closer to the CDC's recommended 150 minutes of moderate intensity physical activity a week or roughly 8,000 steps of brisk walking.
If all U.S. cities matched Chicago's or Philadelphia's walkability (Walk Score 78), 36 million more Americans could meet national activity targets, a simulation performed as part of the study found. If cities matched New York City's walkability (89), that number could rise to 47 million.
One group, however, did not see a step-count bump: women over 50.
The researchers suggested this could stem from safety concerns, caregiving responsibilities and poor transit access.
"Improving the built environment is a great start, but it's not kind of this one size fits all improvement that benefits absolutely everybody," Althoff said. "It still needs to be paired with targeted health intervention."
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In the U.S., more than 8% of all deaths are linked to insufficient physical activity, which is associated with about $117 billion in annual healthcare costs, according to the CDC.
"Physical inactivity is the fourth underlying cause of death in the world and in the country because it contributes to so many chronic diseases as well as infectious diseases and mental health conditions," James Sallis, distinguished professor emeritus at the School of Public Health, University of California at San Diego, said.
Sallis stressed that walkability is about giving people safe ways to reach their destinations without relying on a car.
"Hopefully a study this large and this impressive will help convince city leaders that not making good conditions for walking is really doing a disservice to the residents," he said.
The study's findings highlight the ways in which urban design can significantly influence physical activity and population health, according to Althoff.
"Helping city planners and policymakers know exactly where to direct resources and for the best results of the health of large populations in the cities is a key part," he said.
Ashish Bibireddy, MD, MPH is an internal medicine resident at The Mount Sinai Hospital and a member of the ABC News Medical Unit.
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