Mobility, the ability to move independently, is critical to maintaining independence and quality of life. Among older adults, mobility disability results when an individual cannot meet the demands of the environment. Current approaches to defining mobility rely on distance and time measures, or decompose mobility into subtasks (e.g., climbing, sit to stand), but provide limited understanding of mobility in the elderly. In this paper, a new conceptual framework identifies the critical environmental factors, or dimensions, that operationally define mobility within a given community, such as ambient conditions (light levels, weather conditions) and terrain characteristics (stairs, curbs). Our premise is that the environment and the individual conjointly determine mobility disability. Mobility in the elderly is defined not by the number of tasks a person can or cannot perform, but by the range of environmental contexts in which tasks can be safely carried out: the more disabled, the more restrictive the dimensions.
Aftab E. Patla is with the Department of Kinesiology at the University of Waterloo, Waterloo, ON, N2L 3G1, Canada. Anne Shumway-Cook is with the Department of Rehabilitation Medicine at the University of Washington, Seattle, WA 98195.