"Want to live longer? Reduce your risk of cancer? And heart disease? Then cycle to work," BBC News advises, prompted by a new study that found UK commuters who cycled to work had lower rates of cancer and heart disease, compared to other types of commuters.
The study was well designed as it included more than 200,000 adults working full time away from their homes and aged between 40 and 69 years. Commuting on a bicycle was associated with a lower risk of cardiovascular disease, cancer and death from any cause, while those walking to work only had a lower risk of cardiovascular disease.
This observational evidence adds to other studies to confirm the benefits of physical activity and active commuting in reducing the risk of these conditions.
The main strength of the study is that it made use of real world data on lifestyle and health outcomes. It also adjusted for a wide range of other factors that might affect the risk of cardiovascular disease or certain types of cancer.
As it is often difficult to fit exercise into our daily routine, commuting by foot or bike could be a useful way of achieving recommended levels of physical activity.
Where did the story come from?
The study was carried out by researchers from the University of Glasgow. The UK Biobank (the resource that provided the data used in the study) is supported by the Wellcome Trust, Medical Research Council, Department of Health, Scottish government, and Northwest Regional Development Agency.
Funding for the study was also received from the Welsh Assembly government and British Heart Foundation.
The main facts of the study have been reported accurately in the UK media, including a note that it is not possible to determine clear cause and effect.
What kind of research was this?
This was a prospective cohort study which aimed to investigate the association between active commuting and cardiovascular disease, cancer and death.
This type of study is useful for looking at data collected over a long period of time, but an inherent weakness of this study design is that it can only highlight possible associations, and not prove cause and effects.
What did the research involve?
Between April 2007 and December 2010 over 500,000 adults aged between 40 and 69 years were recruited to the UK Biobank, an ongoing large prospective study set up to improve the prevention, diagnosis and treatment of a wide range of illnesses.
Participants were recruited from across the country, had biological measurements taken, provided blood, urine and saliva samples for future analysis, and gave detailed information about themselves. They agreed to have their health followed for life (or at least 25 years).
At the start of the study the mode of transport used for commuting was recorded using an electronic questionnaire. The participants were asked "In a typical day, what types of transport do you use to get to and from work?" One or more of the following options could be selected:
- car/ motor vehicle
- public transport
These were then grouped into five commuting categories:
- non-active (car/motor vehicle and/or public transport only)
- walking only
- cycling (cycling, or cycling and walking)
- mixed mode walking (non-active plus walking)
- mixed mode cycling (non-active plus cycling, or non-active plus cycling and walking)
During the follow-up period the main outcomes of interest were deaths from any cause, which was obtained from death certificates held by the National Health Service Information centre, and the incidence of cardiovascular disease and cancer, which was established using hospital episode statistics and Scottish morbidity records.
Data was collected on confounding factors, including:
- sociodemographic factors such as level of deprivation and ethnicity
- smoking status
- body mass index
- leisure time
- occupational and physical activity
- sedentary behaviour
- dietary intake
What were the basic results?
A total of 263,540 adults (52.4% of the total recruited to the Biobank), with an average age of 52.6 years, joined this sub-study. Only those in paid employment were included.
During the follow-up period of around five years 2,430 people died, 496 of which were due to cardiovascular disease. There were an additional 3,748 cancer events and 1,110 cardiovascular events.
Cycling was the mode of commuting most strongly linked to reduced risk of death, cardiovascular disease and cancer. When compared to the non-active group the following was seen:
- 41% lower risk of death from any cause (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.42 to 0.83)
- 52% lower risk of death from cardiovascular disease (HR: 0.48, 95% CI: 0.25 to 0.92)
- 46% lower risk of cardiovascular events (HR: 0.54, 95% CI: 0.33 to 0.88)
- 40% lower risk of dying from cancer (HR: 0.60, 95% CI: 0.40 to 0.90)
- 45% lower risk of a cancer event (HR: 0.55, 95% CI: 0.44 to 0.69)
Mixed mode cycling (e.g. train and bike) also saw reduced risk of death from cancer and cancer events.
Walking to work was associated with some reduced risk, but this was only for death from cardiovascular disease (HR: 0.64, 95% CI: 0.45 to 0.91) and the incidence of cardiovascular disease events (HR: 0.73, 95% CI: 0.54 to 0.99).
Cancer risk was not significantly reduced in those who walked to work, including mixed mode walking. Mixed mode cycling did not appear to protect against cardiovascular death or new cardiovascular disease.
How did the researchers interpret the results?
The researchers conclude that commuting on a bicycle was associated with a lower risk of cardiovascular disease, cancer and death from all causes. People who walk to work also have a lower risk of CVD even after adjusting for potential confounders.
Encouraging and supporting active commuting could reduce risk of death and the burden of important chronic conditions.
This prospective cohort study has established that active methods of commuting to work, either walking or cycling, are associated with reduced risk of death, cardiovascular disease and cancer.
Overall this was a well-designed study based on a large collection of real-world data from the UK. The researchers controlled for key socioeconomic and lifestyle confounders.
Although this is an observational study, confidence in the link is improved by its consistency with existing knowledge and research on the benefits of physical activity and the graded response in the results.
Participants from the UK Biobank who were in paid employment were included and are thought to be reasonably representative of the middle-aged general population. Similar links in younger adults can't be assumed.
A limitation of this study is that the participants volunteered to take part and therefore may be healthier than the rest of the population. However, this bias is unlikely to undermine the findings.
It makes sense that those who have a more active lifestyle would reduce their risk of cardiovascular disease or certain types of cancer.
If you are finding it hard to fit the recommended levels of physical activity into your daily routine then using a bike to commute, if possible, could be an ideal solution.
Read more about getting started with cycling.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
BBC News, 20 April 2017
The Independent, 20 April 2017
The Sun, 20 April 2017
Mail Online, 19 April 2017
The Daily Telegraph, 20 April 2017
The Guardian, 20 April 2017
Links to the science
BMJ. Published online April 19 2017