Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Health and Rehabilitation Sciences


Irwin, Jennifer D.


This mixed methods randomized control trial explored the impact of a tailored, Health Belief and Transtheoretical Model informed educational video on undergraduate students’: (1) motivational readiness, self-efficacy, and decisional balance about changing sedentary behaviour; (2) levels of sedentary time; and (3) perceptions of sedentary behaviour over time and when compared to a control condition. Students (N = 160) were randomly assigned to the intervention or control group. Participants completed: two previously validated questionnaires at baseline, immediate post-intervention, and one-month follow-up; and open-ended questions at post-intervention (intervention group only). Linear mixed models and inductive content analysis were used. Significant differences were observed within intervention participants’ self-efficacy (p = .016) and decisional balance (p = .008) at post-intervention, and sedentary time at post-intervention (p = .032) and follow-up (p = .006). Intervention participants reported positive experiences with the video and felt motivated to reduce their sedentary behaviour. This theory-informed intervention shows promise for reducing students’ sedentary behaviours.

Summary for Lay Audience

The prevalence of sedentary behaviours (i.e., sitting time) among university students is concerning. While university students have been identified as one population at greater risk for high levels of sedentary time, the COVID-19 pandemic has amplified the already high sedentary rates of this population. Theory-informed interventions have proven to be successful in reducing the levels of sedentary behaviour experienced among this population. While several health behaviour theories have been studied, research is sparse on the effects of a combined Health Belief Model and Transtheoretical Model informed sedentary behaviour intervention. This thesis examined the impact of a theory-informed, tailored educational video on university students’ motivational readiness, self-efficacy, and decisional balance (pros and cons) relating to changing sedentary behaviours compared to a control condition. This study also examined the effect of the video on students’ levels of sedentary time and perceptions of sedentary behaviour. An evidence-based and theory-informed video was created with a specific focus on Western University students. A randomized control trial was conducted with a sample of 160 undergraduate students. Participants were randomly assigned to either an intervention group (n = 87) who watched the tailored educational video about sedentary behaviour, or a control group (n = 73) who watched a general health education video. Participants were asked to complete two questionnaires three times over the course of the study. Additionally, intervention participants were asked to complete a series of three open-ended questions immediately after watching the tailored educational video. Participants’ motivational readiness, self-efficacy, decisional balance, and sedentary time were assessed over time and within as well as between groups. Despite no difference found between groups, researchers found that intervention participants increased their self-efficacy and decisional balance, and decreased their sedentary time immediately after watching the video. Intervention participants also continued to decrease their sedentary time when assessed 1-month after watching the video. No significant changes were observed within the control group. Intervention participants described intentions to change their sedentary behaviour after watching the tailored educational video and reported seemingly positive experiences. Overall, the theory-informed educational video shows promise as an intervention for changing the sedentary behaviours of university students.