Effects of a Workplace Exercise Intervention on Cardio-Metabolic Health: Randomized Controlled Trial

Study Design The study is considered a parallel randomized controlled trial with a 1:1 allocation ratio to intervention group and delayed intervention group.

Recruitment An invitation to attend an informational session will be sent to the employees in the company's headquarter building in Dubai, United Arab Emirates. The invitation will emphasize that participation is voluntary and that participants can withdraw at any time without giving any reason. The informational session will discuss the study details (e.g. eligibility criteria) and some tips for physical activity. All employees who wish to participate will need to sign a consent form. The participants who are eligible will have to take an appointment in the workplace health center to make the required health measurements. A total of 150 participants will be recruited for the study. The eligibility of joining the workplace intervention will be based on the eligibility criteria listed below.

Setting and location The intervention will be conducted in the headquarter building of a semi-government telecommunication company in Dubai, United Arab Emirates. The headquarter building includes a gym and swimming pool. The intervention will use the gym workplace for conducting the exercise sessions.

Sample Size Previous studies concerning physical activity and cardiometabolic risk factors used 80% to 91% power and effect sizes ranging between 0.51 and 1.82 to find a significant difference between groups (8,10, 12-13). There are various reasons for choosing these articles for sample size calculations. For example, one article used a 12-week physical activity intervention and offered 3 sessions of physical activity per week (13). The same article included healthy adult participants (13). In addition, the cited articles were concerned with the effect of exercise on specific metabolic risk factors. These metabolic risk factors were waist circumference, systolic blood pressure. fasting glucose, lipid profiles (8,10, 12-13). More specifically, one article focused on waist circumference and physical activity (8). In contrast another article focused on systolic blood pressure and physical activity (10). For the present study, 124 participants will be required at 80% power. A further 20% more participants will be added because it is expected that participants might drop out during the intervention. Therefore, the investigators will recruit a total of 150 participants. The intervention group will have 75 participants and the delayed intervention group will have 75 participants.

Statistical Analysis Analyses and reporting will be in line with CONSORT guidelines, with all analyses being on an intention-to-treat principle regardless of intervention compliance. For a comparison between intervention and delayed intervention arms of the 12- weeks change in outcomes, the investigators plan to use analysis of covariance model, with baseline values as the covariate to control for chance imbalances at baseline. Age and sex specific interaction analyses will be conducted. In addition, the investigators will adopt a linear mixed model approach to provide the mean intervention effect, and quantification of individual differences in response to the intervention. The clinical significance of the intervention effect will be elaborated with magnitude-based inferences, confidence intervals, and confidence levels. Accepted regression modelling methods will be used to explore the intervention effects on the secondary objectives. Multiple imputation techniques will assess the sensitivity of the analyses to the missing at random assumption. Significance tests at 5%, either t-test or chi squared tests will be used to compare those with complete data and those who have missing outcomes. Finally, the investigators will develop a detailed coding scheme and coding checking protocol, cross tabulation, negative case analysis and respondent validation to enhance dependability and trustworthiness.