>Physical inactivity, which has generally been studied as a precursor or an outcome of disease and disability, is the central focus of this review. The general perspective of this chapter is informed by two fundamental assumptions. First, for most persons 50 years of age and older, increasing age is not a cause of physical inactivity. 13 As noted by Berger, current research, especially by Smith, suggests that 50 percent of the decline frequently attributed to physiological aging is, in reality, disuse atrophy resulting from inactivity in an industrialized world. Second, the ability to remain physically active underpins the ability to perform the activities of daily living.
Move.