The aging population in Hong Kong is projected to reach 36.6% by 2046, with roughly 16.6% of older adults estimated to be mildly frail-a condition linked to higher risks of falls, hospitalization, and mortality. While physical activity (PA) is a key modifiable determinant of frailty, a major service gap exists for mildly frail older adults, who lack tailored support, resources, and long-term self-management programs. Although Hong Kong features over 440 public open spaces equipped with senior-friendly outdoor exercise facilities (OEFs), older adults often lack awareness and knowledge on how to utilize them safely for aerobic, strength, and balance training. Furthermore, existing PA interventions often overlook social-ecological perspectives and fail to optimize built environment resources or address digital literacy barriers to sustain long-term behavior change. To bridge these gaps, our team developed and preliminary-tested OUTDOOR-FIT, a complex, theory-driven, socio-ecological mHealth intervention. OUTDOOR-FIT synergizes Hong Kong's built environment (OEFs), social and volunteer support, individual goal-setting, and digital health technology (a contextually tailored mobile Application) to empower mildly frail older adults to self-manage their PA habits. Building upon promising preliminary findings and qualitative feedback from our initial pilot RCT, the intervention has been refined to incorporate neighborhood OEF environmental audits, supervised outdoor experiential practice sessions, and a train-the-trainer volunteer model to support digital literacy and engagement. The main objective of this study is to evaluate the clinical effectiveness and real-world implementation of the refined OUTDOOR-FIT intervention using a hybrid type 1 effectiveness-implementation design. Primary effectiveness outcomes include physical activity levels, exercise self-efficacy, mental well-being, chronic pain, and social loneliness measured immediately post-intervention, as well as at 3-month and 6-month follow-ups. Guided by the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework, secondary implementation outcomes include Reach, Effectiveness, Adoption, Implementation fidelity, and Organizational Maintenance. This study adopts a mixed-methods design embedded within a two-arm cluster randomized controlled trial (cluster RCT) involving community service units. Mildly frail older adults will be cluster-randomized into either (i) the OUTDOOR-FIT intervention group or (ii) a control group. Quantitative analysis will be conducted to evaluate the immediate and sustained effectiveness of the intervention across the primary health outcomes. The qualitative component will consist of semi-structured interviews with older adult participants and community stakeholders to evaluate intervention adoption, implementation barriers, and long-term organizational maintenance.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
SINGLE
Enrollment
240
Participants in the intervention group will undergo four weekly educational workshops (once per week), with 1 hour duration led by exercise specialists (i.e., certified personal trainer, kinesiologist, degree in exercise or health sciences), and support by volunteers and mobile application (app). Two of these workshops will include two sessions of senior-friendly OEFs visits. The rest of the workshops will cover various topics including introduction of the app, risk management for exercising outdoor, exercise appropriate for frailer older adults, selecting appropriate exercise intensity, using OEFs for aerobic, strength and balance training, postural awareness when using OEFs, management of pain during exercise, and exercise modification principles when using OEFs, home exercise alternatives in bad weather situation. During the four weeks of intervention, participants will be encouraged to use OEFs by themselves with the assistance of the app.
Participants in the active control group will engage in four weekly health education workshops, each lasting for 60 minutes and including exercise experiential sessions. The workshops will be led by exercise specialists (i.e., certified personal trainer, kinesiologist, degree in exercise or health sciences). The workshops focus on the benefits of different exercises for older adults, particularly older adults with mild frailty. Participants have opportunities to experience different modified exercise suitable for frail older adults that could be practiced as home. This comparator was chosen as this kind of workshop is common and traditional way in promoting PA for mildly frail older adults in community settings.
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University
Hong Kong, Hong Kong
Physical Activity Level
Physical activity level will be assessed using the Chinese version of the Community Healthy Activities Model Program for Seniors questionnaire (CHAMPS-C) to evaluate weekly frequency and duration of various physical activities in older adults. The primary metric derived is the total duration (hours per week) spent on physical activities. The score ranges from 0 to 168 hours per week, with higher scores indicating a higher level of physical activity.
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
Exercise Self-Efficacy
The Chinese version of the Exercise Self-Efficacy Scale(SEE-C) was used to assess participants' confidence in maintaining regular exercise. This scale comprises 9 items, each rated on an 11-point Likert scale from 0 (not confident) to 10 (very confident). The mean score of these items, ranging from 0 to 10, represents the overall exercise self-efficacy, with higher scores indicating greater confidence in regularly engaging in exercise.
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
Mental Well-Being
The mental well-being of participants was assessed using the Chinese version of the 7-item Short Warwick-Edinburgh Mental Well-Being Scale (SWEMWBS). This scale addresses both hedonic and eudaimonic aspects of well-being, with items rated on a 5-point Likert scale from 1 (none of the time) to 5 (all the time). The mean score, calculated by averaging responses across the 7 items, reflects the overall mental well-being, with higher scores indicating greater well-being.
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
Pain Severity
Assessed using the Chinese version of the Brief Pain Inventory (BPI-C). The scale evaluates pain severity (4 items, score range 0 to 10) and pain interference with daily functioning (7 items, score range 0 to 10). Items are rated on an 11-point scale from 0 ("no pain" / "does not interfere") to 10 ("pain as bad as you can imagine" / "completely interferes"). Scores are calculated as the mean score for each subscale, with subscale scores ranging from 0 to 10. Higher scores represent greater pain severity or interference (a worse outcome).
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
Social Loneliness
Assessed using the Chinese version of the 6-item De Jong Gierveld Loneliness Scale (DJGLS) to evaluate overall, emotional, and social loneliness. The total score ranges from 0 to 6, with higher scores corresponding to higher levels of perceived loneliness (worse outcome).
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
Organizational Readiness for Adoption
Assessed quantitatively using the Readiness for Implementation Model (RIM) survey administered to community staff and volunteers prior to intervention delivery. The RIM is a multidimensional model comprising 42 elements that evaluate organizational readiness across domains such as leadership support, resource availability, and staff preparedness. Element ratings are combined and converted to an overall readiness index ranging from 0 to 100. Higher scores indicate greater organizational readiness for program adoption and stronger implementation potential (better outcome).
Time frame: Baseline
Implementation Fidelity
Assessed using a 15-item standardized fidelity checklist developed based on the program's workflow to evaluate the consistency of protocol delivery across participating community units. The checklist monitors the successful execution of 9 workshop topics (e.g., app introduction, risk management, pain management), 3 organizational components (e.g., volunteer group formation, group chat creation), and 3 practical workshop activities (e.g., outdoor facility visits). The final fidelity rate is calculated as the average percentage of items successfully implemented within the units, ranging from 0% to 100%. A higher percentage indicates greater consistency and stricter adherence to the intervention protocol (better outcome).
Time frame: Baseline, immediately post-intervention (Month 1)
Organizational Intention to Maintain
Assessed at the organizational level using a single-item question administered to center management and involved staff to evaluate their commitment to sustain the program in the setting after the study ends. The intention to maintain the program is rated on a 5-point Likert scale ranging from 1 (Strongly Disagree / Extremely Unlikely) to 5 (Strongly Agree / Extremely Likely). Higher scores indicate a stronger organizational intention, commitment, and perceived likelihood to sustain and integrate the intervention into the community partners' routine services (better outcome).
Time frame: Baseline, immediately post-intervention (Month 1), 3 months post-intervention (Month 4), and 6 months post-intervention (Month 7)
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