Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Arts




Prapavessis, Harry


Sedentary behaviour (SB) has been linked with a variety of negative health consequences which can be diminished by increasing frequency of breaks. The Health Action Process Approach (HAPA) is an effective behaviour change model for reducing SB in adult office workers. The objective of this study was to evaluate a mobile health HAPA-based sedentary behaviour intervention in office workers. Fifty-three participants (Mean age 40.62, 79.2% women) were randomized into a treatment group or a no-contact control group in a four-week, two-arm parallel randomized controlled trial. All SB outcomes were assessed from Baseline to Week 4, perceived stress was measured at Baseline and Week 4. Large significant effects (hp2 = 0.235 – 0.466) favouring the intervention group were found for break frequency, sitting and moving time. Findings suggest a Smartphone Ecological Momentary Assessment (SEMA3) delivered HAPA intervention can increase SB break frequency and moving time and decrease sitting time in office workers.

Summary for Lay Audience

The main objective of the study was to evaluate a four-week, two-arm randomized controlled trial intervention that was designed to reduce workplace sedentary behaviour by increasing sitting break frequency and break duration and decreasing workplace sitting time while increasing workplace standing time and moving time. Perceived stress was also evaluated to determine if a behaviour change intervention tailored to workplace sedentary behaviour could affect perceived stress levels. The sedentary behaviour and perceived stress outcomes were collected and measured through questionnaires that were delivered through a downloadable mobile phone application. Outcome measures were compared within and between groups to detect differences. Participants were recruited through emails to relevant liaisons and senior executives as well as through emails directly to office working employees throughout Canada. This two-arm, repeated measure randomized controlled trial randomized participants into two groups, an intervention group, and a no-contact control group. The study lasted for four weeks. The intervention group received an initial theory-based behaviour change counselling session through video chat and then continued through a mobile application where weekly theory-based worksheets were delivered to the participants’ mobile phones. These two steps worked to encourage the participant to create his/her own personal and specific action plans and coping strategies. Action plans focus on the where, what, when, and how a strategy should be used, and coping plans focus on thinking about possible barriers to an action plan and how to overcome them. The control group received no intervention or further information from the letter of information. The intervention proved to be statistically effective in increasing sedentary break frequency and moving time and reducing overall sitting time in the intervention group as compared to the control group. The results from the study show that an online theory-based mHealth sedentary behaviour intervention can improve the sedentary profiles of office working adults.

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