Using online computer-tailoring to promote physical activity: a randomized trial of text, video and combined intervention delivery-modes.

Website-delivered interventions are increasingly used to deliver physical activity interventions, yet problems with engagement and retention result in reduced effectiveness. Hence, alternative modes of online intervention delivery need to be explored. Therefore, the aim of this study was to evaluate the acceptability and effectiveness of a computer-tailored physical activity intervention delivered via the Internet in three delivery- modes: video, text, or both. Australian adults (N=803), recruited via e-mail, were randomized into the three delivery-modes and received personal physical activity advice. Intervention content was identical across groups. Repeated measures ANOVA’s were used to compare the three groups regarding acceptability, website usability, and physical activity. Participants in the video group accepted the content of the physical activity advice significantly better (F=5.59; p<0.01), and spent significantly more time on the website (F=21.19; p<0.001) compared to the text and combination groups. Total physical activity improved significantly over time in all groups (F=3.95; p