Thoughts on the built environment, physical activity, and obesity

Obesity is primarily an issue of energy balance in which “energy in” is greater than “energy out”. A lot of factors affect this balance: the food system, work and school environments, physical activity, dietary patterns, social norms that shape these patterns, etc. While the scientific literature goes back and forth on the effects of exercise on weight loss and therefore obesity (which is a topic for another day), physical activity affects the “energy out” part of the balance.

We all know that we need to exercise, so why don’t we? There are lots of reasons for this, but one of the big ones is that our environments aren’t DESIGNED to make healthy choices easier. Sure, you can choose to eat healthy and exercise, but these require deliberate, conscious choices that may be inconvenient compared to less active choices, like buying fast food or driving a car instead of walking. In the US, 25% of car trips are for destinations less than one mile away ([1] — why don’t we walk? Perhaps there weren’t sidewalks, it was just faster to drive or perhaps it was just more convenient to do so.

It wasn’t always this way…

“Back in the day” (pre-1950’s), more physical activity was built into people’s days — they would walk to school, to work, to grocery stores and doctor’s appointments, and other places around town. [2] Not everyone had cars and so communities had to account for walking. As a result, communities used “mixed” land use strategies, meaning that zoning practices allowed commercial and residential activities to occur in the same area and so the everyday person walked more often because the places that s/he had to go were near to where s/he lived. [2] It was common to see buildings in which the ground floor held shops or other commercial enterprises and the upper floors held living spaces. [2] Physical activity was just a fact of life, a way of getting to work and school or the store. Bottom line: pre-1950’s, people didn’t necessarily “exercise” (go for runs, play more baseball, etc.) more — physical activity was just built into their day.

At the end of World War II, communities started to be built with cars as the default mode of transportation (think suburbs, cul de sacs [which prioritize privacy over walkability], and separate residential and commercial zoning codes), making it harder and harder to get around on foot or by bike. [2] Now the average American travels 6.8 miles to get to work, school, or to run an errand [3] and 86.5% of all commuters travel by personal vehicle [less than 5% commute by walking or biking] [1] — this is in part a product of the creation of automobile-centric cities. [3] Over the years, the “spreading out” of communities has forced us to sit in cars more and we sit more and more at work, school, and when we relax, such that our physical activity has drastically decreased, may be part of the reason for the increases in our (collective) waistlines. I’m grossly oversimplifying here, there are many causes of the obesity epidemic, but physical activity definitely affects energy expenditure, so should be a part of the solution.

In addition to educating people about eating healthier and exercising more (by the way, did you get 60 minutes of physical activity in today?), perhaps we should engineer our environments so that we will make healthier choices unconsciously, at least a large percentage of the time. Instead of requiring people to be constantly vigilant, we could make the healthy choices the “no brainers”.

The term “built environment” refers to the design of a city and its physical components, how different activities, such as retail and business, are distributed across the community, how transportation systems function, and how humans move within this environment. [1] Urban planners and designers often assume that people primarily travel for a purpose, to go to the store, to school, to work — and not necessarily because they enjoy the activity itself. [1 In fact, studies suggest that the number one predictor of choosing one form of transportation over another (driving versus walking) was travel time. [1] Another study found that the distance of trips, which served as a proxy measure for resources in a neighborhood (like a nearby grocery store) was negatively associated with walking, whereas neighborhoods with more houses and stores per square mile, a mix of land uses (commercial mixed with retail and residential), and more intersections per square mile were positively associated with walking. [1] With busy schedules and the ever increasing work, this is understandable. However, these findings also suggest that, if you make it more convenient to walk, people will walk.

Perception of walkability and bike-ability can be important, too. For example, 87% of US kids are driven to school in a bus or car, in part because parents fear that they will be injured while traveling to school by foot or bike. [2] Incidentally, the most likely place for kids to get injured is near school because other parents dropping off their kids tend to be in a hurry and are more likely to hit and injure other kids. [2] Urban design components, such as narrower streets, medians, trees, and separate sidewalks and bike lanes might make for safer travel to school and promote active transport. [2] This can also apply to perceptions of safety of recreation spaces: in Chicago and Boston, many children in one study had playgrounds within a reasonable distance from home, but they were considered to be less safe than playgrounds in other areas of these cities [3].

Access to play spaces and recreational facilities can also play a role in increasing physical activity. While some studies have not shown significant associations between the distance between a child’s home and a playground with risk of obesity, other studies have found associations between the number of recreational facilities available within a Census tract and a decreased risk of being overweight [3]. While this last study was in teens, the same might hold true for kids. Shared use agreements, which might be as simple as allowing school playgrounds to be open after-hours or as complex as park districts and school districts sharing facilities, might also be a useful strategy for providing additional play and recreational spaces to a community that might not otherwise have access to such resources. [2]

Interest in how the built environment can be used to influence physical activity behaviors is growing, but change can sometimes be slow. One of the many reasons for this is that policymakers often need local data to justify legislation, especially with ever-tightening budgets. The good news is that investing in walkability and bike-ability is as good for the local economy as it might be for our waistlines: in 2011, the Political Economy Research Institute found that, when legislators invest $1 million into infrastructure projects, they generate more jobs if the project was cycling or pedestrian-related versus when the project was geared only towards roads. [2] However, it can be hard to get local data (especially if you live in rural Anytown, USA) to justify such policy decisions because many studies may not be generalizeable due to the specific place-based nature of the conclusions [4] and many studies have failed to find significant associations between the built environment and childhood obesity. [3,4]

There are a lot of reasons for this. For one, there is not a lot of data that is easily geared towards what researchers would like to study. [3] Researchers often have to make do with the data they have, such as Census tract data, trying to “retrofit” studies to the available data, which in the case of Census data were designed for ease of collection and not with a particular study in mind and as a result, may be hard to spatially match with individual-level variables that may affect mode of transportation and physical activity variables [1,3]. Getting grants to fund less generalizeable research is difficult and conducting surveys to collect place-specific, detailed information on physical activity behaviors is time consuming and expensive [1,3].

Additionally, there may not be language to support walkability or bike-ability in a municipality’s or county’s General Plan and so it might need to be added to be considered in future legislative decisions [2]. Researchers could also improve study designs and methodology (including the reporting of these studies) to try to better detect existing relationships, by including more longitudinal studies (most data on the built environment and physical activity is cross-sectional, making it harder to determine causal relationships [ 1,3,4], more detailed analyses, and more complex statistical models that better take into account multiple variables. [4].

The good news is that there is a lot of interest in improving our environments to help us move more and not every approach has to be complex. Sometimes it takes understanding the barriers (even the small ones) to understand why people are not biking or riding. Sometimes the reasons that people don’t exercise is that they might need a little help with the logistics. In a recent interview, Keith Holt, a leader with Milwaukee Bicycle Works and the Wisconsin Bike Federation, noted that these groups work “to fill in the gaps that prevent people from riding bikes.” [5] Holt originally got his start in Chicago, IL, trying to connect people of color with the local bike federation and found that, for reasons unrelated income, simple things like bike shops being far away and group rides were not easy to access, were keeping people from getting out and riding. [5] He found that the three main barriers to riding have to do with getting a bike, finding somewhere to have it fixed or learning to fix it yourself, and finding someone to ride with. [5] Holt and Milwaukee Bicycle Works try to encourage bike shops to open up in underserved areas, teach people how to fix their bikes, and organize at least informal rides to get people out and riding. Another approach is to take community members on “walking audits” to evaluate first-hand the walkability of their community and spark conversation about how to improve it. [6] Still another approach might is to get language about bike-riding into a municipality’s or county’s General Plan and enact policy based upon it. La Crosse implemented the first county-wide Complete the Streets policy in the state of WI [7] so that now, any new road construction process has to consider walking and biking as modes of transportation. These were relatively simple approaches in concept (not necessarily in implementation), but they can have a big impact.

As with other public health initiatives, developing partnerships between communities, organizations, and government might be a powerful way to work on a common obesity prevention agenda. Rethink, a “health-link” partnership in Winnebago County, Wisconsin, uses this approach to work on health issues related to obesity prevention. The idea is to make an environment in which it is easier to do physical activity by adapting evidence-based strategies to local communities by involving the local community (who knows the community the best? The people who live there!) as well as other stakeholders to work together. [8] As with most problems at the community and societal levels, this addressing low levels of physical activity in our communities will take a lot of working together to come up with solutions and resources to retool our environments to help us move more because no one organization has all of the know-how or resources and since everyone will be affected, everyone has to be a part of the solution.

It is clear that the built environment affects physical activity and over the last 50–60 years, our environments have promoted a sedentary lifestyle that is contributing (or at least not helping) the obesity epidemic. Changing the built environment to make physical activity more convenient may help to get us moving. While a lot of the research has focused on transportation physical activity, other forms of physical activity should be addressed. We need more research as well as more thoughtful and engaged people to think about barriers to physical activity, both large and small, to start implementing solutions to help people overcome them. This will likely take a lot of brainstorming, problem-solving, and hard work to change, but there is a lot of interest out there and we just need a little momentum to start the process.

On that note, let’s get moving.

[1] Handy, Boarnet, Ewing, Killingsowrth. “How the built environment affects physical activity Views from Urban Planning.” Am J Prev Med 2002; 23(2S): 64–73. Accessed 25 October 2015.
[2] ChangeLab Solutions. “Comprehensive Planning for Safe and Active Communities A Webinar on Creating Places for Safe and Active Transportation.” http://www.changelabsolutions.org/publications/comprehensive-planning-safe-and-active-communities Accessed 25 October 2015.
[3] Papas, Alberg, Ewing, Helzlsouer, Gary, and Klassen. “The built environment and obesity.” Epidemiologic Reviews 2007; 29: 129–143. Accessed 23 October 2015.
[4] Ding and Gebel. “Built environment, physical activity, and obesity: what have we learned from reviewing the literature?” 2012; 18: 100–105. Accessed 23 October 2015.
[5] Interview with Keith Holt. “Why does creating active communities make a difference?” http://dhsmedia.wi.gov/main/Play/118e7c0d79dd4223ba127c1e668b79e5 Accessed 24 October 2015.
[6[ Prevention Speaks. “Walkable Neighborhoods.” http://preventionspeaks.org/stories/view/walkable-neighborhoods Accessed 24 October 2015.
[7] Prevention Speaks. “Jack’s Story.” http://preventionspeaks.org/stories/view/jacks-story Accessed 24 October 2015
[8] Podcast interview with Emily Dieringer (Rethink Coalition). Accessed 24 October 2015.

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