Feasibility of Online and On-Site Physical Activity Delivery Among Older Adults: Mixed Methods Pilot Randomized Controlled Trial

Physical activity (PA) is central to healthy aging, yet interventions targeting older adults often report substantial attrition and variable adherence. Although digital and internet-based exercise programs broaden accessibility and flexibility, their ability to sustain engagement compared with traditional on-site formats remains unclear. Understanding how delivery mode influences attrition and adherence-and why participants persist or withdraw-is essential for designing inclusive and sustainable PA interventions.