Aging, frailty, and design of built environments.

Before developing agriculture, herding or metallurgy, humans occupied most of the world. Multiple socioculturally-based responses supported their migration, including building shelters and constructing niches to limit environmental stressors. Sheltered settings provided social support and security during stressful times, along with opportunities for injured, aging, and frail members to survive. Modern built environments are designed for similar purposes, to support human growth, development, reproduction, and maintenance. However, extended survival in modern settings has costs. With age, muscle (sarcopenia) and bone loss (osteopenia, osteoporosis), along with somatic, physiological, and sensory dysfunction, reduce our physical capabilities, increase our frailty, and impede our abilities to interface with built and natural environments and manufactured artifacts. Thereby, increasing our dependence on built environments to maintain autonomy and quality of life.What follows is a conceptual review of how frailty may limit seniors within modern built environments. It suggests age-related frailty among seniors provides specific data for those designing environments for accessibility to all users. It is based in human ecological theory, and physiological and gerontological research showing senescent alterations, including losses of muscle, bone, and sensory perceptions, produce a frail phenotype with increasing age limiting our mobility, activity, use of space, and physical abilities. As an individual phenotype, frailty leads to age-related physical and performance declines. As a physiological assessment, frailty indices amalgamate individual measures of functional abilities into a single score. Such frailty indices increase with age and differ betwixt individuals and across groups. To design built environments that improve access, usability, and safety for aging and frail citizens, today's seniors provide living samples and evidence for determining their future abilities, limitations, and design needs. Designing built environments to accommodate and improve the quality of human-environment interactions for frail seniors will improve usability and accessibility for most user groups.