Intervening on physical activity and sedentary behavior in older adults.

Participating in sufficient levels of physical activity is important for sustaining health and quality of life across the age span. The United States Physical Activity Guidelines recommend individuals of all ages "move more, more often" by frequently engaging in aerobic activity while avoiding prolonged bouts of sitting. This is indicative of a slow shift in focus in the study of active aging that has occurred in the last two decades. Historically, researchers interested in the influence of physical activity on older adults' health and quality of life focused on discrete sustained bouts of intense activity (i.e., structured exercise). More recently the widespread usage of accelerometers contributed to a large body of evidence demonstrating that long periods spent sedentary were associated with a host of negative health outcomes ranging from poorer cardiometabolic health to poorer physical functioning and elevated risk of death. These findings often persisted when controlling for time spent in higher-intensity physical activity, spurring separate fields of intervention research concerned with promoting exercise or reducing sedentary time. Novel data emerging in recent years on the importance of an individual's overall activity profile (i.e., amount and patterning of light and moderate-to-vigorous activity) has driven yet another shift in focus toward interventions focused explicitly on movement profiles. In this narrative review, we discuss the evolution of thought regarding older adults' physical activity behaviors. We highlight successes and challenges in first promoting structured and prolonged exercise, later in targeting sedentary behavior, and most recently in attempting to intervene on activity profiles. We end our review by highlighting current gaps in research and important future directions.