Jen Akeroyd
Most health researchers define health as physical, mental, social and financial well-being (World Health Organization, 1948). This is the first Focus article in a series that will report on the state of the evidence that explores the ways mass transit is associated with health benefits and risks. In this article a growing body of research examining the physical activity benefits of mass transit is summarized.
The majority of the U.S. population is not physically active at levels that promote health and prevent disease (National Center for Health Statistics, 2011). A strong body of evidence reports that insufficient levels of physical activity have a greater impact on mortality and cardiac events as compared to traditional risk factors for cardiovascular disease such as smoking, hypertension and hyperlipidemia (e.g. Mark and Lauer, 2003; Myers et al., 2005). Little to no physical activity has also been implicated in obesity, type-two diabetes, osteoporosis, colon and breast cancers, and anxiety and depression (CDC, 2008).
The Center for Disease Control (CDC) recommends that adults engage in 150 minutes of aerobic activity (e.g. brisk walking) every week, which translates to approximately 20 minutes per day. Even 10-minute bouts throughout the day are effective in promoting health and preventing disease (CDC, 2008).
Several researchers have estimated the time spent walking to and from mass transit stations. Besser & Dannenberg (2005) analyzed data from a U.S.-based national telephone survey of mass transit users and reported that the median transit user walked 19 minutes per day five days per week as part of his or her commute, and nearly 29% of the transit users reported walking 30 minutes a day or more. Wener and Evans (2007) used a more objective measurement of physical activity by collecting pedometer data that compared mass transit users’ versus car commuters’ time spent walking. They reported that mass transit users walked an average of 30% more steps per day. Wener and Evans’ results are consistent with the findings of LaChappelle and Frank (2009). Using geographic information systems and self-report data from a sample of persons in metropolitan Atlanta, Georgia, LaChapelle and Frank compared the physical activity levels of those using mass transit versus driving a car to get to and from work. Mass transit users were 3.87 times more likely to achieve recommended levels of physical activity than car commuters. In summary, researchers reporting on data from across the U.S. have consistently found that the amount of walking involved in getting to and from mass transit stations is one way individuals can achieve 20 minutes of walking per day.
Are transit users walking at a brisk enough pace to achieve health benefits? While few studies have examined this phenomenon, MacDonald and colleagues (2010) used a pre+post experimental design to compare changes in body mass index (BMI) and obesity levels among U.S. residents who used a newly implemented mass transit system to similarly situated residents who did not use the mass transit system. On average, mass transit users significantly reduced their BMI by 1.18 kg/m2 over a period of approximately 20 months. The authors note that this would translate into a 6.45-pounds’ weight loss for a person who is 5’5″. MacDonald and colleagues projected that this reduction in BMI would translate to an 81% reduced odds (95% CI=0.04, 0.92) of becoming obese over time. Importantly, in this study the mass transit users as compared to car drivers were living in the same neighborhoods with similar commuting patterns and shared perceptions of neighborhood environments.
While there is limited evidence supporting the health benefits of physical activity of mass transit users, several scholars have researched and reported on the physical activity benefits of walking for transportation (as opposed to leisure or recreation), arguably a similar phenomenon to walking to and from transit stations. For example, Hamer and Chida (2008) conducted a meta-analysis of 18 studies examining walking for transportation on cardiovascular outcomes. They reported an 11% reduction of cardiovascular disease with 150 minutes or more time spent walking at a moderate pace. Similarly, Luoto and colleagues (2000) reported that rates of breast cancer are significantly lower in women who walk at least 30 minutes per weekday while commuting to and from work.
Overall, the current state of evidence suggests that persons who ride mass transit are, on the average, engaging in health-enhancing physical activity by simply walking to and from transit stations. However, more research is needed to substantiate these findings.
References
◆ Besser, L. M., & Dannenberg, A. L. (2005). “Walking to public transit: Steps to help meet physical activity recommendations.” American Journal of Preventive Medicine, 29(4),273-280.
◆ Center for Disease Control. (2008). “Physical activity guidelines for adults.” Retrieved from http://www.cdc.gov/physicalactivity/professionals/index.html
◆ Hamer, M., & Chida, Y. (2008). “Active commuting and cardiovascular risk: A meta-analytic review.” Preventive Medicine, 46(1), 9-13.
◆ LaChapelle, U. & Frank, L.D. (2009). “Transit and health: mode of transport, employer-sponsored public transit pass programs, and physical activity.” Journal of Public Health Policy, 30, S73-S94.
◆ Luoto, R., Latikka, P., Pukkala, E., Hakulinen, T. & Vihko, V. (2000) “The effect of physical activity on breast cancer risk: a cohort study of 30,548 women.” European Journal of Epidemiology, 16, 973-980.
◆ MacDonald, J.M, Stokes, R.J., Cohen, D.A., Kofner, A, & RIdgeway, G.K. (2010). “The effect of light rail transit on body mass index and physical activity.” American Journal of Preventative Medicine, 39(2), 105-112.
◆ Mark, D.B., & Lauer, M.S. (2003). “The prognostic variable that doesn’t get enough respect.” Circulation, 108, 1534-1536.
◆ Myers, J., Kaykha, A., George, S. et al. (2005). “Fitness versus physical activity patterns in predicting mortality in men.” American Journal of Medicine, 117, 912-918.
◆ National Center for Health Statistics. (2011). “Health, United States, 2010: with special feature on death and dying.” Hyattsville, MD.
◆ Wener, R.E. & Evans, G. W. (2007). “A morning stroll: levels of physical activity in car and mass transit commuting.” Environment and Behavior, 39 (1), 62-7.
◆ World Health Organization. (1948). Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19 June – 22 July, 1946; signed on 22 July 1946 by the representatives of 61 States. Retrieved from http://www.who.int/suggestions/faq/index.html
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