Sunday, March 2, 2014

Research Highlights: London Public Bike-Sharing Programs May Improve Some Aspects of Citizen Health

London Public Bike-Sharing Programs May Improve Some Aspects of Citizen Health

In an era of sedentary lifestyles and environmental pollution, the idea of a “healthy city” that promotes walking and cycling in lieu of motorized transport has become increasingly popular. In 2010, the government of London, UK introduced a public bike sharing system that allows citizens to rent bikes from various stations located all over the city. A study published in the British Medical Journal examined whether this new system actually improves the health of citizens and makes London a “healthier city”. 578,607 London bike users over the age of 14 participated in this study by renting bikes between April 2011 and March 2012. Experimenters set up two scenarios: one in which the bike-sharing system existed and one in which it did not, and then modeled changes in user physical activity, intake of PM2.5 air pollutants, and incidence of road accidents in each scenario as ways of comparing user health.

Physical activity was measured in metabolic equivalent of tasks (MET). After applying statistical analyses, the results of this study showed that MET improved by 0.06 per week per person when citizens used the bike sharing system. This is not very significant on an individual scale, but would lead to a huge improvement in citywide health if applied to all citizens. The largest health benefit for men was reduced risk for heart disease, while for women it was reduced risk for clinical depression.

Inhalation of air pollutants did not improve much with bike usage: although bike users were more removed from sites of high air pollutant concentration (i.e. busy roads and London Underground tunnels), bike users experienced more frequent breathing as a result of their exercise and thus inhaled a similar level of air pollutants to non-cyclists. Results also showed that road accident rates decreased for bike users, though this was only shown to be statistically significant for small injuries. In general, experimenters found that health benefits were much more prominent in male participants and in older participants.

Experimenters tested how results could have been affected by multiple confounding parameters in order to identify the weaknesses of this study. One prominent weakness was that the road accident component of this study relied on police injury reports, not hospital records, to estimate a bike user’s risk of injury. This means that experimenters likely overestimated the risk level of using public bikes. Another weakness of this study was that experimenters were unable to measure baseline health and physical activity of the participants, so the estimated health benefits of public bikes may be inaccurate. However, none of these weaknesses drastically affected the accuracy of this study. Overall, the study relied on an effective model that, despite some limitations, showed bike-sharing systems to benefit the physical activity and health of bike users in some ways. More research is needed to determine the full health benefits of bike sharing programs, as this study was specific to London and applied only in the short to medium term.

BMJ 2014;348:g425

Caroline Russell-Troutman is the 2013-2014 Research Highlights Editor

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