Virtual Trainer System (3rd Version) for Physical Activity Promotion in Middle-aged Hong Kong Adults

Hong Kong is a highly urbanized city that many people work long hours daily and over the week, especially for those middle-aged adults. The limited time and lack of professional exercise instruction are always the barriers for them to participate in physical activity (PA). With the advances in information technology (IT), the knowledge of PA can be rapidly disseminated through the Internet and smartphone. We design an IT- instruction based lifestyle intervention program, with the purpose to improve PA level and health status in a sample of middle-aged Hong Kong adults. A two-arm parallel individual level randomized controlled trial (RCT) named "Follow Your Virtual Trainer (FYVT)" will be conducted among 200 healthy and sedentary Chinese adults aged from 40 to 65 years. The participants will be randomly allocated into intervention group or control group. Those in intervention group will under the instruction of a web-based computer software termed "Virtual Trainer", which interact with their smartphone apps, to conduct a 3-month self-planned PA training program. A serious of online video seminars with healthy lifestyle themes will be released to the participants biweekly among 3 months. After that, 6 months observation will be followed. Those in control group will only receive a written advice of standard PA recommendation, and the textual content of the seminars. The assessments will be implemented at baseline, 3, 6, and 9 month. Primary outcome is PA measured by accelerometer and International Physical Activity Questionnaire; the second outcomes include cardio-respiratory fitness, resting energy expenditure, anthropometrics, body composition, blood pressure, health-related quality of life, sleep quality and quantity, fatigue, behavior mediators, and maintenance of PA.

Inclusion criteria

• aged 40 to 65 years
• able to understand Cantonese and read Chinese
• self-reported inactivity (no habitual exercise experience for at least 6 months)
• the baseline resting energy expenditure (REE) is less than 1.05 kcal•min-1 for men and 0.85 kcal•min-1 for women
• reachable by telephone
• have basic computer skills
• have smartphone and always surf internet (at least 4 times per week)
• will not leave Hong Kong for a long time (longer than 2 months) during the study period

Exclusion criteria

• self-reported history of cardiovascular and pulmonary diseases, neurological disorder, musculo-skeletal disorder, and osteoarthritis
• receiving medically prescribed diet or PA intervention
• blood pressure ≥ 160/100 mmHg
• using of medication that may influence exercise performance
• for women, currently pregnant or plan to become pregnant in the next 1 years, and those receiving hormonal therapy