It’s no big secret that one of the keys to good health is getting regular exercise. Yet good intentions are often thwarted by factors outside of one’s control. A person might decide to jog or bike several times a week, but if the neighborhood outside their door is not conducive to physical activity, it can be easier said than done. Whether you live out in the country or deep in the heart of the city, the design of the neighborhood around you can have an effect on your ability to exercise out of doors.
To clarify that relationship between neighborhood streets and physical activity, epidemiologist Ningqi Hou used data from one of the largest longitudinal studies of cardiovascular health in the United States, the CARDIA study. As a graduate student at the University of North Carolina, Hou and her colleagues analyzed the frequency of physical activity in over 5,000 CARDIA participants alongside characteristics of the “street networks” where they live. Hou, now a postdoctoral researcher in the Department of Health Studies at the Medical Center, looked at the density of intersections, the connectivity of streets, and the type of roads in each participant’s neighborhood.
Their hypothesis was that the “built environment,” the infrastructure surrounding a person’s home, has an invisible influence on their behavior that could conflict with their exercise plans.
“Although there are a lot of physical activity interventions, a lot of them don’t actually work. For example, you have an education program to tell people how beneficial physical activity could be, but over time, that effect is going to fade,” Hou said. “However, your built environment is really just existing there for you, and you are passively receiving its influences. To build a sustainable intervention, you need to know what works in that environment.”
The results of the analysis, published in December in Health & Place, were more complex than just “more roads, more exercise.” In areas of low urbanicity – rural and exurb regions with small, spread out populations – more connected street networks did indeed promote walking, jogging, and bicycling. Specifically, a higher density of intersections was associated with more outdoor exercise, suggesting that long, country roads are better suited to physical activity when they are connected instead of remote. That information could be valuable for civic planners looking to build “exurban” neighborhoods that promote health, instead of sprawling suburbs filled with meandering drives and cul de sacs.
“For the ongoing projects we can still influence that process and hopefully help planners to build a more physical activity-friendly environment,” Hou said. “Sometimes when I see the cookie-cutter communities, they have a very suburban style of being spread out, and it kind of worries me. But I think our result may do some good in informing policymakers to change the design for new communities.”
But in more densely packed areas of high urbanicity, the street network effect reversed for women. The higher the density of local roads, the less often female residents biked, jogged, or walked on average (men were unaffected). This unexpected result suggested that other factors associated with high population and street density – such as crime, or socioeconomics – could counteract the exercise benefits of a more connected neighborhood, Hou said. It also suggests that changing urban neighborhoods to promote physical activity may be more complex than adding intersections.
“Sometimes I struggle with it, because it’s the built environment, it’s concrete, so how do we actually modify it?,” Hou said. “The built environment is really the hardware, and we definitely need software.”
If crime is a major factor in keeping women from exercising outdoors, a stronger police presence or indoor exercise facilities might off-set the negative association with street networks, she said. Adding more parks and other types of green space to a dense urban environment might also promote healthy behavior – offering a safe location for walking, biking or jogging and reducing the density of streets.
Some exercisers may actually be inconvenienced rather than improved by a thick network of streets and intersections in the city; for instance, cyclists who have to brake at red lights and stop signs every block. The complex effect found in Hou’s study underscores that smart civic development – and smart physical activity interventions tailored to the unique character of a neighborhood – are what is needed to reverse unhealthy trends in Americans both rural and urban.
Hou, N., Popkin, B., Jacobs Jr., D., Song, Y., Guilkey, D., Lewis, C., & Gordon-Larsen, P. (2010). Longitudinal associations between neighborhood-level street network with walking, bicycling, and jogging: The CARDIA study Health & Place, 16 (6), 1206-1215 DOI: 10.1016/j.healthplace.2010.08.005