A conceptual framework of frailty: a review.

This article presents an overview of the increasingly common condition of frailty, which by and large lacks clarity of definition. A variety of sources provide this statement regarding definition, incidence, causation, rate, and time of appearance. Utilizing the newly elaborated process of symmorphosis, which explains the coadaptation of structure and function secondary to altered energy loads, I propose that frailty is a body-wide set of linked deteriorations including, but not confined to, musculoskeletal, cardiovascular, metabolic, and immunologic systems. The common final pathway that leads to this constellation of findings is usually keyed to a decline in physical activity either as a result of habit or disease inputs. As such, the state of frailty is largely separable from the process of aging and should thereby be susceptible to active intervention and reversal.