target range is not achieved. Here is a brief review of the major findings. • For individuals who perform no or little moderate-to-vigorous physical activity, replacing sedentary behavior with light-intensity physical activity reduces the risk of all-cause mortality, cardiovascular disease incidence and mortality, and the incidence of type 2 diabetes. Before this report, evidence that light-intensity physical activity could provide health benefits had not been clearly stated. • Individuals who perform no or little moderate-to-vigorous physical activity, no matter how much time they spend in sedentary behavior, can reduce their health risks by gradually adding some or more moderate-intensity physical activity. • For individuals whose amount of moderate-to-vigorous physical activity is below the current public health target range of 150 to 300 minutes of moderate-intensity physical activity, even Part A. Executive Summary 2018 Physical Activity Guidelines Advisory Committee Scientific Report A-5 small increases in moderate-intensity physical activity provide health benefits. There is no threshold that must be exceeded before benefits begin to occur. • For individuals whose physical activity is below the current public health target range, greater benefits can be achieved by reducing sedentary behavior, increasing moderate-intensity physical activity, or combinations of both. • For any given increase in moderate-to-vigorous physical activity, the relative gain in benefits is greater for individuals who are below the current public health target range than for individuals already within the physical activity target range. For individuals below the target range, substantial reductions in risk are available with relatively small increases in moderate-intensity physical activity. • Individuals already within the physical activity target range can gain more benefits by doing more moderate-to-vigorous physical activity. Individuals within the target range already have substantial benefits from their current volume of physical activity. • Bouts, or episodes, of moderate-to-vigorous physical activity of any duration may be included in the daily accumulated total volume of physical activity. The 2008 Physical Activity Guidelines for Americans recommended accumulating moderate-to-vigorous physical activity in bouts of 10 minutes or more. Research now shows that any amount of moderate-to-vigorous physical activity counts toward meeting the target range. Previously, insufficient evidence was available to support the value of bouts less than 10 minutes in duration. The 2018 Committee was able to conclude that bouts of any length contribute to the health benefits associated with the accumulated volume of physical activity. Efforts to promote physical activity can be effective. The 2008 Scientific Report included no information about methods of promoting and facilitating healthy levels of physical activity. The 2018 Scientific Report includes a summary of major findings from the large body of scientific literature about promoting physical activity through different interventions. • Strong evidence demonstrates that individual-level interventions can increase the volume of physical activity performed by youth and by adults, especially when the interventions are based on behavioral change theories and techniques. • School-based, especially multi-component, programs and community-wide physical activity programs can be effective. Part A. Executive Summary 2018 Physical Activity Guidelines Advisory Committee Scientific Report A-6 • Environmental and policy changes that improve access to places where people can be physically active, modify the built environment to better support physical activity behaviors (including physically active transport), and that, in general, make it easier for people to be physically active can be effective. • Information and communication technologies, including wearable activity monitors, telephone and smartphone programs and applications, computer-tailored print interventions, and the Internet, can be used to enable self-monitoring, deliver messages, and provide support, all of which are helpful in promoting regular physical activity. PUBLIC HEALTH IMPACT The public health impact of insufficient physical activity and the potential gains from even small population-wide increases are substantial. Information contained in this report indicates that, in addition to a reduced risk of death, greater amounts of regular moderate-to-vigorous physical activity reduce the risk of many of the most common and expensive diseases or conditions in the United States. Heart disease, stroke, hypertension, type 2 diabetes, dementia, depression, postpartum depression, excessive weight gain, falls with injuries among the elderly, and breast, colon, endometrial, esophageal, kidney, stomach, and lung cancer are all less common among individuals who are or become more physically active. In addition, this report provides evidence that for some of these conditions, individuals who are or become more physically active, relative to their peers with the same condition, have a reduced risk of mortality, reduced risk of developing other chronic diseases or conditions, and reduced risk of progression of the disease they already have. They also have improved physical function and better quality of life. Each of these conditions alone adds substantially to annual direct