Bicycling in the right direction? : Two systematic literature reviews with meta-analyses of cycling and cardiovascular disease, followed by national correlates of commuter cycling and the presentation of a novel bike tra c index to describe trends in cycling over the years.

Abstract

Background: The world population needs to be more physically active. Cardiovascular disease (CVD) is one of the leading causes of death and can be prevented by physical activity. Cycling as transportation may be a means of improving the health of the general population. To facilitate and evaluate interventions to increase cycling in Norway, we need more information about factors associated with cycling and a method to follow future trends.

Main aims: To investigate the relationship between cycling and CVD and its associated risk factors and to investigate individual and environmental factors that may affect Norwegian people’s choice to travel by bicycle. We also aimed to develop a sensitive method to describe cycling trends in Norway over the years at the local, regional, and national levels.

Materials and methods: This thesis is based on two systematic reviews and meta-analyses of CVD and associated risk factors in more than one million individuals, as well as a crosssectional study of Norwegian public-sector employees in Sogn og Fjordane, Aust Agder and West Agder counties that used a web-based questionnaire combined with objective measurement by a geographical information system. Finally, the thesis is based on opensource data from 89 stationary cycle trips counters in Norway describing the trends in counted trips from 2017 to 2020.

Main results: Based on the systematic review, we found that cycling was associated with a 22% lower risk of CVD mortality, CVD incidence, and associated CVD risk factors compared with passive transport (Study I). Being a cyclist was also associated with beneficial risk factor levels, except for blood pressure, compared with non-cyclists (Study II). In the Norwegian environment, we found both individual and environmental factors associated with a higher likelihood of commuter cycling. Travel distance below 5 km and living in a highly populated area increased the probability of cycling. Having good health, being physically active, and owing an e-bike also increased the likelihood of cycling (Study III). Finally, we observed an 11% increase in counted cycle trips from 2018 to 2020, with large geographical differences (Study IV).

Conclusions: Cyclists were at lower risk of CVD incidence, CVD mortality, and some CVD risk factors. Health professionals, city planners, and stakeholders can recommend cycling to prevent CVD and should aim to increase the amount of cycling. Both individual and environmental factors were associated with likelihood of being a cyclist. Characteristics of cyclists seemed to be similar regardless of whether they lived in areas with smaller or larger numbers of cyclists. Nationally, we observed a significant increase in counted trips, while the regional and local indices indicated geographical differences. The indices may highlight effects related to local and national bicycling strategies.