The 'Outdoor Rehab-Fit' App-based Physical Activity Education Intervention for Frail Older Adults in Hong Kong

In recent years, research teams around the world have developed interventions to educate older adults to use outdoor exercise facilities (OEFs) to improve health outcomes like strength, balance, mobility, PA level, and weight. These interventions employed trainers or therapists to instruct, and monitor exercise training for older adults using the public accessible OEFs. Apart from therapist or trainer-led intervention, an Australian research team developed a mobile application, and social support strategies to help participants to use OEFs to enhance their aerobic and resistance-based PA. A recent local in-depth qualitative study discovered that OEFs in Hong Kong attracted frailer older adults (i.e., those who recovered from a major illness or who has chronic diseases), and their caregivers to use OEFs to support and maintain their daily PA behavior. Some used OEFs to complement their formal rehabilitation sessions. It appears that OEFs in Hong Kong serves as an important health maintenance space for frailer older adults in the city to "age in place", yet educational training related to OEFs has been lacking over the years. Signage besides the exercise equipment has been the only education material for users over the years. A mobile app-based physical activity education intervention will be developed for frail old adults in Hong Kong. The intervention has two components: (1) mobile app; and (2) face-to-face group session that teaches the how to use correctly and safely use OEF in public parks to maintain PA habits. The main objective of this study is to evaluate the feasibility, acceptability, and pilot effectiveness of the 'Outdoor Rehab-Fit' App-based physical activity education intervention. Primary outcomes include recruitment rate, retention rate, attrition rate, attendance, perceived usefulness of the app. Secondary outcomes include exercise self-efficacy, mental well-being, physical activity level. This study adopts a mixed-method design with quantitative