Online sharing of physical activity: does it accelerate the impact of a health promotion program?

Influence on health behavior from peers is well known and it has been shown that participants in an online physical activity promotion program are generally more successful when they share their achievements through an online community. However, more detailed insights are needed into the mechanisms that explain the influence of a community on physical activity level (PAL). This paper discusses a detailed analysis of a data set of participants in an online physical activity promotion program. The analysis focuses on the comparison two groups of participants, namely participants who will join a community at some point in time and participants who will never join a community. A well-balanced selection is made to eliminate to a large extent factors that dilute the effect of the willingness to partake in a community. We create statistical models that describe the PAL increase at the end of the program. A comparison of these models shows that participants that will participate in a community not only have a higher PAL at the start of the program, but also that the PAL increase is significantly greater compared to participants that will not members. The results further support the hypothesis that the possibility to share achievements is an important feature of successful health promotion programs. At the same time, it raises the question whether part of the success is caused by a selection bias, as people that are willing to participate in a community are already more active at the start.