Background: Online health communication has the potential to reach large audiences, with the additional advantages that it can be operational at all times and that the costs per visitor are low. Furthermore, research shows that Internet-delivered interventions can be effectivein changing health behaviors. However, exposure to Internet-delivered health-communication programs is generally low. Research investigating predictors of exposure is needed to be able to effectively disseminate online interventions. Objective: In the present study, the authors used a longitudinal design with the aim of identifying demographic, psychological, and behavioralpredictors of visiting, using, and revisiting an online program promoting physical activity inthe general population. Methods: A webpage was created providing the public with informationabout health and healthy behavior. The website included a "physical activity check,"which consisted of a physical activity computer-tailoring expert system where visitors could check whether their physical activity levels were in linewith recommendations. Visitors who consented to participate in the present study (n = 489) filled in a questionnaire that assessed demographics, mode of recruitment, current physical activity levels, and health motivation. Immediately after, participants received tailored feedback concerning their current physical activity levels and completed a questionnaire assessing affective and cognitive user experience, attitude toward being sufficiently physically active, and intention to be sufficiently physicallyactive. Three months later, participants received an email inviting them once more to check whether their physical activity level had changed. Results: Analyses of visiting showed thatmorewomen (67.5%) than men (32.5%) visited the program. With regard to continued use, native Dutchparticipants (odds ratio [OR] = 2.81, 95% con idence interval [CI] = 1.16-6.81, P = .02)and participants with a strong motivation to be healthy (OR = 1.46, CI = 1.03-2.07, P = .03) were most likely to continue usage of the program. With regard to revisiting, older participants (OR = 1.04, CI = 1.01-1.06, P = .01) and highly educated participants (OR = 4.69, CI = 1.44-15.22,P = .01) were more likely to revisit the program after three months. In addition, positive affective user experiencepredicted revisiting (OR = 1.64, CI = 1.12-2.39, P = .01). Conclusions: The results suggest that online interventions could specifically target men, young people, immigrant groups, people with a low education, and people with a weak health motivation toincrease exposure to these interventions. Furthermore, eliciting positive feelings in visitorsmay contribute to higher usage rates.

Health Communication Exposure Research Subject Selection Web-Based Interventions Internet

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