Effectiveness of a web-based computer-tailored intervention promoting physical activity for adults from Quebec City: a randomized controlled trial

Abstract

Background: The primary objective of this study was to determine the effectiveness of a 3-month web-based computer-tailored intervention on moderate-to-vigorous physical activity (MVPA) in adults. Methods: A total of 242 Canadian adults aged between 35 and 70 years were randomized to an experimental group receiving the intervention or a waiting list control group. The fully automated web-based computer-tailored physical activity intervention consists of seven 10- to 15-min sessions over an 8-week period. The theoretical underpinning of the intervention is based on the I-Change Model. Results: A repeated-measures ANOVA using a linear mixed model showed a significant ‘group-by-time’ interaction favoring the intervention group in self-reported MVPA (p =.02). The MVPA was similar in both groups at baseline (mean ± SD; 176 ± 13 vs. 172 ± 15 min/week, p =.72) and higher in the intervention than in the control group at a 3-month follow-up (259 ± 21 vs. 201 ± 22 min/week, p =.04). This finding was comparable across women and men (group-by-sex, p =.57) and across participants meeting or not physical activity guidelines at baseline (group-by-baseline physical activity, p =.43). Although engagement to the web-based sessions declined over time, participants completing more web sessions achieved higher self-reported MVPA (p