Life Space and Digital Biomarkers: An Assessment of Healthy Aging Using Smartwatches

Life-space Mobility, defined as the spatial extent of an individual's habitual independent movement within the Community, has emerged as a meaningful indicator of functional capacity and healthy aging in older adults. Broader life-space is associated with higher physical activity levels, better cognitive function, greater social participation, and reduced mortality risk. The widespread adoption of consumer-grade wearable devices (e.g., smartwatches and accelerometer-based trackers) has created new opportunities for the objective, continuous, and ecologically valid assessment of physical activity and mobility-related digital biomarkers, including daily step count, distance walked, time in moderate-to-vigorous physical activity (MVPA), and sedentary time. Despite growing interest in linking these biomarkers to life-space outcomes, the extent, nature, and methodological diversity of available evidence remain poorly characterized. This scoping review aims to map the current evidence base by identifying, describing, and synthesizing studies that have used wearable devices to capture digital biomarkers of physical activity and have concurrently assessed life-space mobility in community-dwelling older adults.