JMIR Publications

ABSTRACT

Background:

Physical activity (PA) is central to healthy ageing, yet interventions targeting older adults often report substantial attrition and variable adherence. Digital and internet‑based exercise programs broaden access and flexibility, but their ability to sustain engagement compared with traditional onsite formats remains uncertain. Understanding how delivery mode influences attrition and adherence - and why participants persist or withdraw - is essential for designing inclusive and sustainable PA interventions for older adults.

Objective:

This study aimed to explore whether delivery mode (online vs onsite) affects attrition, adherence, physical activity levels, physical function, and mental and health-related quality of life in older adults, and to examine participants’ reasons for attrition and motivations for adherence using a mixed methods approach.

Methods:

This 26-week pragmatic pilot trial employed an embedded convergent mixed methods design. Community-dwelling adults aged ≥60 years (N=35) living in three residential areas in Sweden were cluster-randomised by site to an online (prerecorded video-based Otago exercises; n=12) or onsite (group-based, in-person Otago exercises; n=23) delivery mode. Quantitative outcomes included attrition, adherence to the intervention goal (2 walks and 2 exercise sessions per week), physical activity level (Godin Shepard Leisure Time Exercise Questionnaire), lower body strength (Chair Stand Test), depressive symptoms (Geriatric Depression Scale), and health related quality of life (EQ5D3L), assessed at baseline, mid-intervention (14 weeks), and postintervention (26 weeks). Analyses included t-tests, chi-square tests, ANCOVA, and mixed between-within ANOVAs. Semi-structured interviews were conducted with participants who completed (n=17) or withdrew (n=7) from the intervention and analysed using qualitative content analysis. Integration followed COMB (Capability, Opportunity, Motivation) principles.

Results:

Overall attrition was 37.1% (13/35), with no significant difference between delivery modes (P=.29); most dropouts occurred within the first two weeks. Mean adherence did not differ significantly between the online (M=17.0, SD=6.70) and onsite (M=12.1, SD=10.1) groups (P=.19). Across both groups, physical activity increased over time (time effect: P=.02), and lower body strength improved significantly (P<.001), with gains maintained at postintervention. No significant effects were observed for depressive symptoms or health-related quality of life. Qualitative findings indicated that attrition was primarily driven by physical health issues and perceived lack of fit, while adherence was supported by appeal and reward, routine and commitment, flexibility, self-monitoring, and (often) social presence.

Conclusions:

In this pragmatic pilot trial, online and onsite PA delivery modes produced comparable outcomes for attrition, adherence, and health measures among older adults. Findings suggest that delivery mode alone may be less important than early support, flexibility, and perceived relevance. Larger, adequately powered trials are needed to identify subgroups that may benefit most from specific delivery formats and to test strategies that reduce early attrition. Clinical Trial: ClinicalTrials.gov NCT05885308; retrospectively registered May 30, 2023.