Cellular telephones measure activity and lifespace in community-dwelling adults: Proof of principle

Objective: To describe a system that uses off-the-shelf sensor and telecommunication technologies to continuously measure individual lifespace and activity levels in a novel way. Design: Proof of concept involving three field trials of 30, 30, and 21 days. Setting: Omaha, Nebraska, metropolitan and surrounding rural region. Participants: Three participants (48-year-old man, 33-year-old woman, and 27-year-old male), none with any functional limitations. Measurements: Cellular telephones were used to detect in-home position and in-community location and to measure physical activity. Within the home, cellular telephones and Bluetooth transmitters (beacons) were used to locate participants at room-level resolution. Outside the home, the same cellular telephones and global positioning system (GPS) technology were used to locate participants at a community-level resolution. Physical activity was simultaneously measured using the cellular telephone accelerometer. Results: This approach had face validity to measure activity and lifespace. More importantly, this system could measure the spatial and temporal organization of these metrics. For example, an individual's lifespace was automatically calculated across multiple time intervals. Behavioral time budgets showing how people allocate time to specific regions within the home were also automatically generated. Conclusion: Mobile monitoring shows much promise as an easily deployed system to quantify activity and lifespace, important indicators of function, in community-dwelling adults.