Physical inactivity is one of the ten leading risk factors for death worldwide. Approximately 5.3 million people die prematurely every year due to cardiovascular diseases, breast and colon cancer and diabetes and other illnesses associated with sedentary lifestyles. According to The Lancet Physical Activity Series Working Group, more physical activity can increase global life expectancy between 0.41 and 0.95 years. The World Health Organization (WHO) recommends at least 150 minutes of moderate-intensity physical activity throughout the week.

In order to maintain moderate physical activity, many people tend to think just about exercise. Nevertheless exercise is just “a subcategory of physical activity that is planned, structured, repetitive, and aims to improve or maintain one or more components of physical fitness”. Health specialists define physical activity as “any bodily movement by skeletal muscles that requires energy expenditure – including activities undertaken while working, playing, carrying out household chores, travelling, and engaging in recreational pursuits.”

So, would walking to the bus stop make up for structured gym time? Researchers in Bogotá explored the issue and found surprising results. In the recently published paper “TransMilenio, a Scalable Bus Rapid Transit System for Promoting Physical Activity”, a team of researchers concluded that using Bogotá’s bus rapid transit (BRT) system was associated with meeting the WHO’s recommended level of physical activity.

The research shows that TransMilenio riders were more likely to have more than 22 minutes a day and 150 minutes per week of moderate-to-vigorous physical activity than non-users. The findings bolster the case for how investing in public transport is an investment in the health of the city.

More Transit Ridership Makes for a More Active City

The researchers from Universidad de Los Andes schools of Engineering and Medicine, Universidad Jorge Tadeo Lozano and World Resources Institute (WRI), conducted the long version of the International Physical Activity Questionnaire (IPAQ) with 1000 adults and measured physical activity with a sub-sample of 250 individuals who wore accelerometers 12 hours a day for seven days (except when sleeping, showering or swimming).

The survey included information about the participants (sex, age, marital status, education, monthly household income, neighborhood socio economic stratus, occupation over the last 30 days, years lived in the neighborhood, and motorcycle and car ownership) as well as minutes spent on each transport mode (public bus, BRT, feeder bus, car, taxi, motorcycle, and others) over the previous 7 days. The researchers also evaluated the walkability of the neighborhoods where the surveys were conducted.

Statistical analysis of the surveys showed that 58 percent of the users of TransMilenio were likely to walk to and from transport modes more than 150 minutes per week, while 48 percent of than nonusers of the BRT system met this minimum.  The research also shows that there were no significant differences according to socioeconomic status or sex. Data from the sub-sample of people wearing accelerometers was consistent with the survey results: TransMilenio users walked more than non-users (median 38.4 minutes vs. 28.0 minutes per day). Interestingly, women and people with low income were more likely to average over 22 minutes of activity daily.

Furthermore, the research found that this greater physical activity has an effect on health savings. The economy saved between 3 and 22 percent of each dollar spent on TransMilenio, as walking to and from the BRT stations led to reduced illness like diabetes, ischemic heart disease and cancer. In dollar terms, this savings amounts to approximately US $2.63 – $17.55 per user per year, which is between 1 percent and 5 percent of the average users’ annual medical costs.

These findings from Bogotá are consistent with similar studies conducted in Curitiba and in King County, Washington, where transit use was associated with more than 10-12 minutes of physical activity per day. The US National Household Travel Survey also shows walking to transit associated with physical activity.

A Case for Further Investment

It is clear that simply walking to the BRT station will not be enough to completely reduce obesity and associated diseases. Even someone who spends 150 minutes a week on moderate-to-vigorous physical activity also needs to follow a healthy diet and to refrain from smoking, among other things. Nevertheless, the health impact of BRT systems is typically framed in terms of reducing travel times, while curbing traffic incidents, air pollution and greenhouse gas emissions. This research changes that.

The authors conclude: “Our study underscores the potential importance of BRT in increasing walking for transport. This study provides evidence of the benefit of incorporating considerations of increasing walking into public transportation planning to increase physical activity and prevent non communicable diseases in the world’s rapidly urbanizing cities”.

TransMilenio needs improvement, but this new study should give decision makers yet another reason how investing in the system can benefit the health of a city as a whole.

These results were recently highlighted in Public Radio International, where Jason Margolis explains why taking the bus is better for your health than driving.