Correlation and causation?
I’ve seen a number of links today to this Swedish study showing people who commute by bike are healthier (mentally and physically) than those who drive or take public transportation.
Researchers in Sweden looked at 21,088 adults who commute by walking, driving or bus / train and work full time jobs in Scania, Sweden. In addition to questions on demographics and commute mode, the researchers asked questions about job stress, sleep time, sleep quality, and exhaustion (which the researchers call “low vitality” in their report). Scania and its principle city, Malmö, are located at the southern tip of Sweden and directly across Øresund (“The Sound”) from Copengagen, Denmark.
The surveys show that cyclists sleep better, have less stress, are healthier, suffer less exhaustion, and use fewer sick days than car drivers. Cyclists generally fare better than transit riders in those categories with a few exceptions: People with short (under 30 minutes) transit rides say they sleep better than cyclists.
The survey shows that overall mental health seems about the same across all modes of transport, with one exception: Transit riders with a longer than one hour commute scored lower on mental health than other categories (and perhaps validating the “creeps and weirdos” stereotyping of bus riders?) Mental health was scored using GHQ-12, a standardized psychometric mental health questionaire. The other surprise: those with long (greather than one hour) car drives scored better than those with intermediate (30 to 60 minute) car commutes.
The response from cycling advocates on Twitter, Facebook and Google Plus has been that this survey shows cycling can lead to improved physical health and mental health.
I’m going to be contrarian and provide another possible explanation: only healthy people ride bicycles to work. Sickly folks with low vitality drive because they simply don’t have the energy to get on a bike and go. Cyclists also must have a better self image in the first place to counter the dominant cultural value which emphasizes car travel over active transportation (even in Scania, Sweden, where 71% of commuters drive to work).
I personally believe cycling makes me fitter, stronger, healther, and more balanced than driving to work does, but I don’t believe we can conclude that from the Swedish study.
You can download the the complete published study here.
Speaking of Sweden: Is today the right time to point out the plague of tatooed Swedish devil girls who pull down the pants of innocent cyclists?