In developed and many developing countries physical inactivity is one of the most important public health problems of the 21st century . There is strong evidence linking physical inactivity with various chronic conditions, such as coronary heart disease, stroke, type 2 diabetes, cancer, obesity and mental health problems [1–3], and physical inactivity has been identified as a leading risk factor for mortality, estimated to cause 6% of deaths globally . In contrast, the numerous benefits of a physically active lifestyle have been well documented . Despite the preceding evidence, in England only 29% of women and 39% of men report doing sufficient physical activity to meet the minimum recommended guidelines of 150 minutes of moderate intensity physical activity per week or 75 minutes of vigorous intensity physical activity per week . This level of physical inactivity is estimated to cost the United Kingdom National Health Service £0.9 billion per year .
Substantial health benefits can be achieved through relatively modest changes in activity behaviour among large segments of the population , and therefore physical activity interventions are now considered to be as important to population health as other high profile interventions, such as those lowering tobacco use or reducing blood pressure . Although the health benefits of physical activity are now well-established, little is known about the effectiveness of interventions designed to improve population physical activity . The majority of physical activity interventions have been delivered at the level of the individual, aimed at changing personal behaviour . To change population prevalence, interventions need to be effective, but they also need to reach large numbers of people. Although some individual-level interventions are effective, their reach is limited when compared with community-level interventions. It is community-level interventions that have the potential to produce long-lasting benefits for the whole community, but evidence as to which type of community-wide interventions are most effective is currently weak .
A recent review of research examining the effectiveness of community-level interventions to promote physical activity reported that many studies used weak evaluation designs, such as uncontrolled, pre-post evaluations, and could not attribute any observed changes to the intervention . One example of a community-level intervention evaluation that did include control communities—but was non-randomised—was the ‘Cycling Demonstration Towns’ programme in England , in which the intervention involved town-wide media campaigns, personalised travel planning, cycle training, repair services, and cycling infrastructure improvements. A controlled, repeated cross-sectional study examined the effect of the intervention in six towns between 2005 and 2008 using telephone surveys of quota samples of local residents . The average annual percentage increase in the number of cyclists on the road was 4%. Net increases were also found in the proportions of residents who reported cycling for at least 30 minutes on 12 or more days per month (0.97% or 1.65%, depending on the choice of control areas) .
Reviews of physical activity correlates suggest that a combination of personal, social and environmental factors are associated with physical activity prevalence , but there are very few evaluations of the effects of changes to either social or built environments, and studies of the built environment are almost exclusively restricted to urban environments [10, 13]. Both urban and rural dwellings report similarly low levels of physical activity in adults: on average, 9.5 days per month (95% CI: 9.3-9.6) of moderate-to-vigorous intensity physical activity for at least 30 minutes . Although 20% of the population live in non-urban dwellings , rural populations are generally understudied [13, 14]. Additionally, access to recreational facilities and other environmental supports for physical activity (e.g., neighbourhood ‘walkability’, convenient access to destinations, and perceived safety) have been shown to be related to physical activity participation , with people in rural areas being more likely to report lack of facilities as a barrier to physical activity .
Randomised controlled trials are considered the most powerful tool in research design for evaluating interventions, due to their rigorous study design and strict randomisation procedures . Traditional randomised controlled trials, where individual participants are randomised, are not always reproducible in the real world and tend to focus on individuals rather than communities, raising doubts about whether a subsequent scaling up of individual interventions to larger populations would lead to changes in population prevalence . It has been suggested that when evaluating interventions that are by necessity delivered to groups rather than individuals, cluster randomised trials, which randomise groups (e.g., communities, villages, towns) and measure outcomes on individual participants within those groups, are more appropriate [9, 19].
Cluster randomised trials commonly use a parallel group design, in which the clusters are randomised to either the intervention or control arm of the study. For practical reasons it is often not possible to deliver an intervention to many clusters at the same time. In addition, it is often regarded as unethical to withhold an intervention from a proportion of participants if it is believed that the intervention will do more good than harm. In these circumstances, stepped wedge trial designs , where the intervention is delivered sequentially to all trial clusters over a number of time periods, is an alternative to the traditional parallel groups design. In a stepped wedge design, clusters effectively cross over from the control to the intervention group. The stage at which the clusters cross over is randomised. Outcomes are measured on the study participants in all clusters at every time period so that each cluster provides data points in both the control and intervention conditions . Examples of stepped wedge investigations include the efficacy of Hepatitis B vaccinations , the effect of housing improvements on respiratory health symptoms , and different tuberculosis treatments on number of disease episodes .
The objective of this paper is to describe the protocol of a stepped wedge cluster randomised trial for evaluating the effectiveness of a community-level intervention to increase physical activity in rural villages in southwest England. The intervention will identify community needs and then provide resources and support to initiate local activity programmes, ultimately aiming for the activities to become self-sustaining over time. The intervention is expected to improve physical activity participation after each village receives the intervention. It is also anticipated that changes will be observed in levels of social support, physical activity intentions, awareness and use of local facilities, and perceived village supportiveness of physical activity.