Living in an activity-friendly neighbourhood could mean people take up to 90 minutes more exercise per week, according to a study published in The Lancet today. With physical inactivity responsible for over 5 million deaths per year, the authors say that creating healthier cities is an important part of the public health response to the global disease burden of physical inactivity.
The study included 6822 adults aged 18-66 from 14 cities in 10 countries from the International Physical activity and Environment Network (IPEN) . The cities or regions included were Ghent (Belgium), Curitiba (Brazil), Bogota (Colombia), Olomouc (Czech Republic), Aarhus (Denmark), Hong Kong (China), Cuernavaca (Mexico), North Shore, Waitakere, Wellington and Christchurch (New Zealand), Stoke-on-Trent (UK), Seattle and Baltimore (USA).
The research team mapped out the neighbourhood features from the areas around the participants' homes, such as residential density, number of street intersections, public transport stops, number of parks, mixed land use, and nearest public transport points. Physical activity was measured by using accelerometers worn around participants' waists for a minimum of four days, recording movement every minute.
On average, participants across all 14 cities did 37 minutes per day moderate to vigorous physical activity - equivalent to brisk walking or more. Baltimore had the lowest average rate of activity (29.2 min per day) and Wellington had the highest (50.1 min per day).
The four neighbourhood features which were most strongly associated with increased physical activity were high residential density, number of intersections, number of public transport stops, and number of parks within walking distance. The researchers controlled for factors including age, sex, education, marital and employment status and whether neighbourhoods were classed as high or low income. The activity-friendly characteristics applied across cities, suggesting they are important design principles that can be applied internationally.
The difference in physical activity between participants living in the most and least activity-friendly neighbourhoods ranged from 68-89 minutes per week, representing 45-59% of the recommended 150 minutes per week.
Professor James Sallis, lead author of the study from the University of California, San Diego (US), explains: "Neighbourhoods with high residential density tend to have connected streets, shops and services meaning people will be more likely to walk to their local shops. Interestingly, distance to nearest transport stop was not associated with higher levels of physical activity, whereas the number of nearby transport stops was. This might mean that with more options, people are more likely to walk further to get to a transport stop that best meets their needs. The number of local parks was also important since parks not only provide places for sport, but also a pleasant environment to walk in." 
"Despite its humid subtropical climate that usually makes people less physically active, Hong Kong showed above-average levels of physical activity, similar to those observed in New Zealand," says Professor Ester Cerin, co-author from the University of Hong Kong "Hong Kong has very high residential density and good transport access. This combination means that people are more likely to walk to local services, or to catch a metro, bus or boat on a daily basis. When done regularly, this kind of incidental physical activity accumulates and is an important contribution to overall levels of physical activity." 
Professor Sallis adds: "Physical inactivity has been linked to diabetes, heart disease, and some cancers. Creating healthier cities could have an important impact on improving levels of physical activity. As part of their response to rising levels of non-communicable diseases, public health agencies should work with the urban planning, transport, and parks and recreation sectors towards making cities more activity-friendly than they are today." 
Writing in a linked Comment, Dr Shifalika Goenka, Public Health Foundation of India, Delhi, India, estimates that the "total health gained by changing to optimal activity friendly environments will be close to 2 million fewer deaths and around 3% fewer non-communicable diseases." Dr Goenka says that although the article presents clear evidence for the role of the urban built environment in enhancing physical activity levels of entire populations, "other vital attributes of the built environment that support physical activity and are taken for granted in all the countries of Sallis and colleagues' study, might not be noted in many other developing countries and need urgent attention - safety, pedestrian priority, availability of adequately wide, useable, unencroached pedestrian pathways, convenience and safety in cycling, and adequate capacity in public transport."
She concludes: "We need interventions to counter the rapidly growly inactivity that urbanisation leads to, by providing environments that change the way we live our daily lives. It is high time that built environments provide the quadruple boost towards health, environment, equity (or public good), and habitat."
NOTES TO EDITORS:
Funding for coordination of the IPEN adult study, including the present analysis, was provided by the National
Cancer Institute of National Institutes of Health (CA127296) with studies in each country funded by different sources.
 IPEN http://www.
 Quotes direct from authors and cannot be found in text of Article.
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