People who cycle to work are about half as likely to develop cancer or heart disease as those who get to work by car or public transit, according to the results of a large British study released Thursday.
Walking to work was associated with cardiovascular benefits, although not as much as cycling, the study also found.
The findings suggest, write the study’s authors, that communities could greatly increase the health of their residents by implementing “policies that increase active commuting, particularly cycling, such as the creation of cycle lanes, cycle hire or purchase schemes, and better provision for cycles on public transport.”
The Twin Cities has already made considerable progress in the building of this cycling infrastructure, which is why it consistently ranks among the top “bike-friendly” urban areas in the United States. More than 13 percent of Twin Citians cycle to work, at least once in a while, according to the Minnesota Department of Transportation (MnDOT).
Five years of data
For the study, which was published in the BMJ (formerly the British Medical Journal), a team of researchers from the University of Glasgow used five years of data collected from more than 263,540 people participating in UK Biobank, a large database set up in the U.K. to help that country’s health officials collect information about preventing, diagnosing and treating a wide range of diseases. The average age of this sample of participants was 53, and none had a history of cancer or heart disease. All were employed and had answered questions about their usual mode of commuting to work.
During that five-year period, 1,110 of the participants were diagnosed with heart disease and 3,748 were diagnosed with cancer. A total of 2,430 participants died. Of those deaths, 496 were related to heart disease and 1,126 were related to cancer.
A closer look at the numbers revealed an association between how people commuted to work and their risk of disease. Cycling to work was associated with a 41 percent lower risk of dying overall compared to commuting by car or public transport. More specifically, the cyclists had a 52 percent lower risk of dying from heart disease and a 40 percent lower risk of dying from cancer. They were also 46 percent less likely to develop heart disease and 45 percent less likely to develop cancer during the period of the study.
Even when people combined cycling with “non-active” transport (car and/or public transit), their risk of death from all causes fell 24 percent, including a 36 percent drop in their risk of dying from cancer.
Walking to work was not associated with a lower risk of dying from all causes. Walkers were, however, 27 percent less likely to develop heart disease and 36 percent less likely to die from it.
“The fact that [the walkers’] health benefits were more modest may be related to distance, since they commute fewer miles on average in the U.K. — six per week compared to 30 for cyclists,” write two of the study’s authors, Jason Gill and Carlos Celis-Morales, in an article about the study for The Conversation. “They may therefore need to walk longer distances to elicit meaningful benefits. Equally, however, it may be that the lower benefits from walking are related to the fact that it’s a less intense activity.”
The study did find that the further people cycled or walked to work, the lower their risk of heart disease or cancer.
Limitations and implications
In a commentary that accompanies the study, Lars Bo Andersen, an exercise epidemiologist at the Western Norwegian University of Applied Science, explains why the study’s findings could be important. He points out that within the five-year timeframe of the study, there were 37 deaths among the study’s 6,751 commuting cyclists.
“If cycling is directly responsible for a mortality reduction (and we cannot say for sure with this design), … 63 participants would have died if they had all commuted by car or public transport,” he writes.
That may seem like a small number — until you extrapolate it across large populations, he adds.
But as Andersen notes, this study is observational, which means it can’t prove that commuting by bike (or on foot) is the direct reason for the positive health outcomes associated with those modes of transport. Although the researchers adjusted for a wide range of health influences — including gender, age, socioeconomic status, ethnicity, smoking, body mass index, other types of physical activity, diet and time spent sitting — other factors, not identified in the study, may explain the results.
Also, the participants self-reported the information on how they got to work and the distance of their daily commute. Such self-reports can be unreliable.
Still, as Gill and Celis-Morales point out, their study “builds on the evidence from previous studies in a number of important ways. Our quarter of a million participants was larger than all previous studies combined, which enabled us to show the associations between cycling/walking to work and health outcomes more clearly than before. In particular, the findings resolve previous uncertainties about the association with cancer, and also with heart attacks and related fatalities. We also had enough participants to separately evaluate cycling, walking and mixed-mode commuting for the first time, which helped us confirm that cycling to work is more beneficial than walking.”
“In addition, much of the previous research was undertaken in places like China and the Nordic countries where cycling to work is common and the supporting infrastructure is good,” they add. “We now know that the same benefits apply in a country [the U.K.] where active commuting is not part of the established culture.”
For more information: The study and the commentary can be read in full on the BMJ website.