A blended intervention to promote physical activity, health, and work productivity among office employees using intervention mapping: a cluster-randomized controlled trial

Physical activity (PA) is related to decreased risks for morbidities and mortality. Among working populations, PA may also be a risk factor for absenteeism and presenteeism. The World Health Organization (WHO) recommended at least 150 min/week moderate- to-vigorous intensity PA (MVPA) for adults for health. However, more than half of adults in Hong Kong did not meet the recommended level. Compared to great efforts made for promoting PA for children, few attentions have been paid to those at work. Web-based interventions have been growing rapidly in the past decade. Existing evidence has suggested this type of interventions an effective means to improve PA and health. However, several challenges limit application of the web-based interventions, in particular smaller long-term effects and lower participant engagement and retention rates compared to traditional workplace-based approach, where face-to-face workshops or counselling, posters or other intervention format adopted. A blended approach combining web-based and traditional workplace-based forms might lead to more effective. However, research on this topic is scarce. Following the intervention mapping (IM), we developed a 3-armed cluster randomized controlled trial (cluster-RCT) to improve PA, health, and work productivity among a randomly selected sample of office employees in Hong Kong. The three arms are: a purely web-based intervention arm, a blended intervention arm combining the web-based components with face-to-face workshops and posters, and a control arm. The intervention is personally tailored based on social psychological theories. It will last for three months and then participants will be followed up for nine months to examine long-term effects of the intervention. The primary outcome will be objectively measured MVPA using an accelerometer. Secondary outcomes will consist of health-related variables (including adiposity, blood pressure, blood sugar, blood lipids, self-reported depression, anxiety, stress, and health-related quality of life) and work-related variables (including absenteeism and presenteeism). We will primarily aim to compare between-group differences in the abovementioned outcomes, with a hypothesis in favor of the blended intervention. Secondly, we will examine between-group differences in participant engagement and retention, as well as mediation and moderation effects of theoretical determinants of MVPA change (such as motivation, self-efficacy, and intention) and socio-demographic factors. If effective, the intervention can be promoted to all office employees in Hong Kong to promote their PA, health and work productivity. In addition, our findings, if effectiveness is more favorable in the blended intervention arm, will implicate a new direction for similar interventions in the world.