Strongest benefits seen for cyclists

Commuters who cycle or walk to and from work or study may be at lower risk of mental and physical health problems than people who do not rely on these options, according to a large long-term study published in the open-access journal BMJ Public Health.

While health benefits were seen for both forms of active commuting, the greatest health benefits were seen among cyclists, who had a 47% lower risk of death from any cause, the findings show.

Active travel is considered one of the most practical and sustainable ways to increase daily physical activity, and there is growing evidence that it has health benefits, the researchers said.

But existing evidence is hampered by short monitoring periods, limited age groups and limited health outcomes, they add.

To address these shortcomings, the researchers used nationally representative data from the Scottish Longitudinal Study (SLS). This study is based on 5% of the Scottish population, derived from the 1991, 2001 and 2011 census results.

The researchers focused on 16- to 74-year-olds who travelled to the UK to work or study in 2001. After exclusions for incomplete data, the final analysis was based on 82,297 individuals.

Census respondents were asked to select which mode of transportation they used for the longest part, based on distance, of their usual commute. Active travel was defined as walking or cycling. All other commuting modes were defined as “inactive.”

The responses covered hospital admissions in the country from all causes: cardiovascular disease, cancer and traffic accidents; deaths from all these causes; and prescriptions for mental illnesses (tranquilizers, anti-anxiety drugs and antidepressants) from 2001 to 2018.

Several potentially influential factors were considered. These included age, gender, pre-existing health conditions, as well as socio-economic factors and distance to work/study.

Between 2001 and 2018, 4,276 participants died (just over 5% of the study group), of whom almost half died from cancer (2023; 2.5%). Some 52,804 (just over 64%) were admitted to hospital, 9,663 (12%) of them because of cardiovascular diseases, 5,939 (just over 7%) because of cancer and 2,668 (just over 3%) after a traffic accident.

A total of 31,666 participants (38.5%) were prescribed a drug related to cardiovascular disease between 2009 and 2018, and 33,771 (41%) were prescribed a drug for poor mental health during the same period.

Compared with inactive commuters, those who walked to work/study were more likely to be female, younger, work shifts, have shorter commutes and live in a city. They were also less likely to have dependent children and generally had lower household income and education levels.

It also emerged that commuters who cycled were more likely to be male, younger, work shifts and live in the city. They were also less likely to be homeowners or caregivers.

After accounting for potential confounding factors, active commuting was associated with a lower risk of death and mental and physical health problems, compared with ‘inactive’ commuting.

Specifically, cycling to work was associated with a 47% lower risk of death, a 10% lower risk of hospitalization, and a 24% lower risk of hospitalization due to cardiovascular disease.

It was also associated with a 30% lower risk of being prescribed a drug to treat cardiovascular disease, a 51% lower risk of dying from cancer, and a 24% lower risk of being hospitalized for the disease. In addition, there was a 20% lower risk of being prescribed drugs for mental health problems.

However, bicycle commuters were twice as likely to be admitted to hospital after a traffic accident as ‘inactive’ commuters.

Pedestrian traffic was associated with an 11% lower risk of hospitalization for any reason and a 10% lower risk of hospitalization for cardiovascular disease. It was also associated with 10% and 7% lower risks of prescription medications to treat cardiovascular disease and mental health problems, respectively.

This is an observational study and as such, no firm conclusions can be drawn about causal factors. And the researchers acknowledge several limitations of their study. For example, the census responses reflect only one point in time and do not include overall physical activity levels. And prescription data were only available from 2009.

The census data also did not account for multimodal travel, which could lead to a potential overlap between active and ‘inactive’ commuters, they point out.

But they nevertheless conclude: “This study strengthens the evidence that active commuting has health benefits at the population level and may contribute to reduced morbidity and mortality. That commuting by cyclists and pedestrians is associated with a lower risk of prescription medication for poor mental health is an important finding.

“These findings provide direct evidence for the health benefits of active commuting in a Scottish context, which supports current policy. This study has wider global relevance for efforts to reduce carbon emissions and transition to more active and sustainable travel modes.”

But they warn: “Our finding that commuters who cycle are twice as likely to be killed by road traffic compared to non-active commuters underscores the need for safer cycling infrastructure.”