Systematic review and meta-analysis of reduction in all-cause mortality from walking and cycling and shape of dose response relationship

Abstract

Background and objectiveWalking and cycling have shown beneficial effects on population risk of all-cause mortality (ACM). This paper aims to review the evidence and quantify these effects, adjusted for other physical activity (PA).Data sourcesWe conducted a systematic review to identify relevant studies. Searches were conducted in November 2013 using the following health databases of publications: Embase (OvidSP); Medline (OvidSP); Web of Knowledge; CINAHL; SCOPUS; SPORTDiscus. We also searched reference lists of relevant texts and reviews.Study eligibility criteria and participantsEligible studies were prospective cohort design and reporting walking or cycling exposure and mortality as an outcome. Only cohorts of individuals healthy at baseline were considered eligible.Study appraisal and synthesis methodsExtracted data included study population and location, sample size, population characteristics (age and sex), follow-up in years, walking or cycling exposure, mortality outcome, and adjustment for other co-variables. We used random-effects meta-analyses to investigate the beneficial effects of regular walking and cycling.ResultsWalking (18 results from 14 studies) and cycling (8 results from 7 studies) were shown to reduce the risk of all-cause mortality, adjusted for other PA. For a standardised dose of 11.25 MET.hours per week (or 675 MET.minutes per week), the reduction in risk for ACM was 11% (95% CI = 4 to 17%) for walking and 10% (95% CI = 6 to 13%) for cycling. The estimates for walking are based on 280,000 participants and 2.6 million person-years and for cycling they are based on 187,000 individuals and 2.1 million person-years. The shape of the dose–response relationship was modelled through meta-analysis of pooled relative risks within three exposure intervals. The dose–response analysis showed that walking or cycling had the greatest effect on risk for ACM in the first (lowest) exposure interval.Conclusions and implicationsThe analysis shows that walking and cycling have population-level health benefits even after adjustment for other PA. Public health approaches would have the biggest impact if they are able to increase walking and cycling levels in the groups that have the lowest levels of these activities.Review registrationThe review protocol was registered with PROSPERO (International database of prospectively registered systematic reviews in health and social care) PROSPERO 2013: CRD42013004266.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-014-0132-x) contains supplementary material, which is available to authorized users.

The impact of changes in leisure time physical activity on changes in cardiovascular risk factors: results from The Finnmark 3 Study and SAMINOR 1, 1987–2003

“…A sedentary lifestyle is considered a health risk, and physical activity is an important modifiable factor contributing to risk reduction of cardiovascular diseases (CVD) and death [1–3]. Although the incidence of CVD in Norway has declined over the last decades [4], CVD is still a major cause of premature death and morbidity, and focus on preventive measures such as physical activity should continue [5–7].…”

The mortality impact of bicycle paths and lanes related to physical activity, air pollution exposure and road safety

“…Based on a meta-analysis, the first one focused on cycling, Kelly et al (2014) suggest a relative mortality risk of 0.90 (95% CI = 0.87 to 0.94) for 100 minutes of cycling per week. This implies that with an increase of 100 minutes cycling per week the risk reduction for all-cause mortality is 10% as compared with non-cyclists.…”

“…an almost two-fold greater reduction of the odds of dying per MET hour than for walking and cycling. This suggests that cycling, and walking specific estimates like the meta-analyses by Kelly et al (2014), are needed to estimate the health benefits of cycling and walking. These are not yet available for morbidity (Oja et al, 2011).…”

“…This paper compares the relative size of the health impact of bicycle infrastructure among cyclists related to more time spent cycling (or walking), air pollution and road safety, the three most important factors for the health impact of cycling (De Hartog et al, 2010;Van Kempen et al, 2010). We restrict our analysis to mortality impacts as those related to morbidity are not as well understood Kelly et al, 2014;Oja et al, 2011).…”

“…Various studies found the health effects of more cycling related to road safety and air pollution are small compared with the effect of increased levels of physical activity, even though different methodologies were used (De Hartog et al, Götschi et al, 2015;Rojas-Rueda et al, 2012;Woodcock et al, 2013). As we do not aim to repeat research on the health impact of increased bicycle use, we use the outcomes of the most recent metaanalysis by Kelly et al (2014) on the risk of all-cause mortality in relation to time spent cycling and walking (active travel). In Figure 4, we included 'time spent on active travel' instead of cycling to include the possibility of an exchange between cycling and walking (see e.g.…”