City wide programmes that promote cycling – such as London’s new bike hire scheme – seem a great way to get the public active and tackle the obesity epidemic. But new research published in the BMJ suggests that interventions to promote cycling don’t have much discernible effect after all.

Public health programmes that specifically aimed to increase cycling in a population found increases the the proportion of trips made by bike or the number of bike trips per person of 3.4 percentage points at the most, whereas there was little evidence that cycling increased physical activity or reduces obesity population wide.

Adults in the UK are supposed to at least 150 minutes of moderate intensity physical activity or 75 minutes of vigorous physical activity a week, but few manage. Cycling can fit relatively easily people’s daily routines as a means of travel from place to place, so people might be more inclined to adopt and maintain this type of physical activity than something like running or swimming. Also, if people cycle rather than take the bus or get in their cars, they’re helping to reduce harmful traffic pollution – so cycling could help the environment as well as provide a double whammy of health benefits.

The authors of this paper looked at 25 controlled or “before and after” studies on the effect of various different cycle schemes, such as free bike programmes, building new cycle routes, and promoting cycling to families. The studies were from seven countries, including the UK and the US.

Six studies assessed programmes that specifically aimed to promote cycling, of which four – an intensive one-to-one scheme for obese women, improvements to a cycle route network, and two multifaceted cycle promotion initiatives at town or city level – were found to be associated with increases in cycling. For example, one study found that improving the connectivity of the cycle route network in the Dutch city of Delft increased the proportion of household trips made by bicycle from 40% to 43% over a three year period compared with a change from 38% to 39% over the same period in an area where no improvements had been made.

A further 16 studies evaluated individualised marketing of “environmentally friendly” modes of transport (walking, cycling, and public transport) via marketing and incentives such as free bus tickets. On average this approach increased the number of cycling trips each individual made by eight a year.

Three other studies examined the effects of efforts to change travel behaviour in general, such as car sharing schemes. Two of these trials found small increases in the proportion of trips made by bicycle or the frequency of cycle trips per person (+1.1 and +0.17 a week, respectively), whereas the third actually found a decrease in the proportion of bike trips of almost 12%.

Only two of the 25 studies assessed looked at the health benefits of schemes to promote cycling, one of which reported a small but positive shift in the amount of overall physical activity in the population studied.

Discussing their less that glowing findings, the authors write that “There is nevertheless a strong case for promoting cycling on health grounds,” pointing to evidence that at an individual level cycling to work or school has been shown to improve cardiorespiratory fitness and reduce mortality. “Promoting cycling is, therefore, a viable approach to improving health,” they conclude.
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Yang L et al. (2010) Interventions to promote cycling: systematic review. BMJ 341:c5293. DOI: 10.1136/bmj.c5293