Findings from a community-based 5-year cluster randomised trial
Masamitsu Kamada, I-Min Lee and Ichiro Kawachi
Despite the well-known health benefits of physical activity, physical inactivity remains highly prevalent globally. Effective population strategies to promote physical activity are needed to reduce the global burden of non-communicable diseases stemming from physical inactivity. But the question is: how do we effectively promote physical activity at the population level, such as in entire communities?
Physical activity is shaped by diverse influences at the individual, environmental, societal and policy levels. As such, multilevel and intersectoral approaches are needed to achieve population-wide changes in physical activity.
Evidence from a few short-term trials has highlighted the difficulty of achieving population-level improvements in physical activity through multi-strategic community-wide interventions. In contrast to individual-level interventions, large-scale social interventions face challenges associated with their complex nature and real-world environments that are difficult to control, and it may take considerably longer to influence population levels of physical activity.
Our study, recently published in the IJE, examined the effectiveness of a 5-year community-wide intervention for promoting physical activity in middle-aged and older adults using a cluster randomised design. The study was conducted in Unnan City, Shimane, Japan.
In this first such cluster randomised trial of a long community-wide intervention for population-level physical activity, adults achieving recommended levels of physical activities increased in the intervention communities compared with the control community (4.6 percentage points of change difference).
The intervention was effective for promoting all types of recommended physical activities — aerobic, flexibility and muscle-strengthening activities. However, a bundled approach, which attempted to promote all forms of recommended physical activities simultaneously, was not effective.
Going back to the question, is it possible to promote physical activity at the population level? Based on our study, the answer is yes. The multi-strategic community-wide intervention was effective in promoting physical activity. More importantly, how we promoted physical activity was a critical determining factor of success. For example, the failure of our bundled (all-in-one) approach suggests that “one thing at a time” — a basic principle of social marketing — may be key to the successful dissemination of physical activity recommendations.
As the World Health Organization and other health agencies recommend multiple types of physical activity (aerobic and muscle-strengthening activities, etc) as a key lifestyle factor for preventing non-communicable diseases, a phased strategy (eg, aerobic activity in the first phase, and muscle-strengthening activity later) is worth considering, especially when resources are limited.
In addition, based on the existing literature, including our current and previous investigations (1-year and 3-year evaluations), one year may be too short to achieve population-wide changes in physical activity through community-wide interventions. Focused promotion strategies sustained for several years may be necessary.
Public health professionals also need to be reminded that dissemination of knowledge does not always translate to dissemination of behaviour change. To effectively change behaviour at the population level, we need to carefully design our interventions.
In our study, the intervention adopted social marketing techniques. These techniques apply marketing principles to create, communicate and deliver value that influences target audience behaviour that benefits society as well as the target audience. We deployed all six social marketing benchmark criteria — behavioural objective, audience segmentation, audience research, exchange, marketing mix and competition — which is rare in physical activity interventions in older populations. Sophisticated social marketing processes should sharpen intervention strategies to achieve actual behaviour change (not just knowledge improvement) at the population level.
Though not always practical or feasible, the design of our study (cluster randomised trial) is considered the optimal design to develop practice-based evidence. The original one-year result from this project received the highest quality ranking (ie, lowest risk of bias) in a review article of 33 studies examining the effectiveness of community-wide interventions. Further high-quality studies and systematic reviews could yield deeper insights into effective population approaches to promote physical activity.
Kamada M, Kitayuguchi J, Abe T, et al. Community-wide intervention and population-level physical activity: a 5-year cluster randomized trial. International Journal of Epidemiology, dyx248, Epub 7 Dec 2017, https://doi.org/10.1093/ije/dyx248.
Masamitsu Kamada is a research fellow at the Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, and the Sasakawa Sports Foundation Overseas Research Fellow. His research focuses on physical activity epidemiology and population health interventions.
I-Min Lee is an associate epidemiologist at the Division of Preventive Medicine, Brigham and Women’s Hospital, and a professor at the Harvard Medical School and the Harvard T.H. Chan School of Public Health.
Ichiro Kawachi is the John L. Loeb and Frances Lehman Loeb Professor of Social Epidemiology and Chair of the Department of Social and Behavioral Sciences at the Harvard T.H. Chan School of Public Health.