Study after study shows that walking is very good for those who are able, and generally more is better. A 2023 study found that even 4,000 steps a day improves all-cause mortality risk. (The U.S average is 4,000 to 5,000.) For each 1,000 extra daily steps, risk decreased by 15%.
Walk Scores have been used since 2007 to quantify how quickly people can typically walk to amenities like grocery stores and schools in an area. Cities are assigned scores from 0 to 100; for instance, Seattle's 74 means it's "very walkable." It may seem self-evident that in cities and towns with better scores people tend to walk more. But it's surprisingly difficult to tease out the cause and effect: Do walkable cities prompt people to take more steps, or do people who want to walk tend to live in more pedestrian-friendly cities?
New research led by the University of Washington provides clear evidence that highly walkable areas lead to significantly more walking. Using data from the Argus step-tracking app, authors compared the steps per day of 5,424 people who moved one or more times among 1,609 cities in the United States. Across all relocations, when the Walk Score rose or fell more than 48 points, average steps increased or decreased by about 1,100 per day. But when people moved between similarly walkable cities, their steps stayed about the same. These findings held across people of different ages, genders and body mass indexes.
For instance, the study tracked 178 people who moved to New York City (Walk Score 89) from different cities with an average score of 48. This group's average daily steps rose by 1,400 upon moving to New York, from 5,600 to 7,000. Moves from New York to less walkable cities showed the inverse: People averaged 1,400 fewer steps.
The authors published their findings Aug. 13 in Nature.
"Some of our prior work suggested that our physical, built environment makes a big difference in how much we move, but we couldn't produce particularly strong evidence showing that was the case," said lead author Tim Althoff, a UW associate professor in the Paul G. Allen School of Computer Science & Engineering. "The large data set we worked with for this new study gave us a unique opportunity to produce this strong, compelling evidence that our built environments do indeed causally impact how much we walk."
This map shows changes in steps between cities of different Walk Scores: Seattle to San Francisco, Dallas to Chicago.Althoff et al./Nature
Working with an anonymized data set from 2.1 million people who used the Argus app between 2013 and 2016, the team pulled a subset who had moved and stayed in their new location for at least three months. They normalized for demographics and changes in seasons. They also filtered out days with fewer than 500 steps or more than 50,000, as well as days around moves.
The greatest change in walking the study observed was in the moderate intensity range (100 to 130 steps per minute). Moves that increased Walk Scores more than 49 points were associated with twice as many subjects recording at least 150 minutes of aerobic activity per week, the recommended minimum.
Althoff stressed that while the study provides the strongest evidence to date, no data set is truly representative of the whole U.S. population. For instance, the subjects in this study had all downloaded a step-counting app, which can affect results.
"Our study shows that how much you walk is not just a question of motivation," Althoff said. "There are many things that affect daily steps, and the built environment is clearly one of them. There's tremendous value to shared public infrastructure that can really make healthy behaviors like walking available to almost everybody, and it's worth investing in that infrastructure."
Other co-authors on this paper include Boris Ivanovic of NVIDIA Research and Jennifer L. Hicks, Scott L. Delp, Abby C. King and Jure Leskovec of Stanford University.
This research was funded in part by the National Institutes of Health, the National Science Foundation and the Gates Foundation.
