No matter how much activity you get, sitting for long periods of time poses a major health hazard, a leading Pasadena scientist said in a new scientific conclusion published in the American Heart Association journal Circulation this week.
“Regardless of how much physical activity someone gets, prolonged sedentary time could negatively impact the health of your heart and blood vessels,” said Deborah Rohm Young, Ph.D., director of behavioral research at Kaiser Permanente Southern California in Pasadena.
Young has studied physical activity interventions and is the lead author of a new American Heart Association statement that warns of increased risk for diabetes, other blood sugar problems, heart disease, stroke and an earlier death as a result of too much inactivity or a sedentary lifestyle.
In January 2014, Circulation also published a Kaiser Permanente study that showed how sedentary behavior and lack of physical activity is linked to heart failure in men. Young also was lead author of the study.
In the new AHA statement, Young and the other authors are recommending that Americans should strive for 30 minutes or so of moderate to vigorous physical activity per day to achieve the AHA’s weekly recommendation of 150 minutes of moderate exercise, or 75 minutes of vigorous exercise.
Instead of lumping all the exercise into one or two days, the goal, according to Young, is to encourage more consistent activity.
“There are many important factors we don’t understand about sedentary time yet. The types of studies available identify trends but don’t prove cause and effect,” said Young. “We don’t have information about how much sedentary behavior is bad for health; the best advice at this time is to ‘sit less and move more.’”
The authors also found that moderate to vigorous physical activity does not cancel out the impact of sedentary time. They say even physically active people who spend a lot of their time being sedentary appear to have increased risk.
Sedentary behaviors include sitting, reclining, or lying down while awake as well as reading, watching television or working on the computer.
The AHA statement says these “inactive activities” mean energy expenditure is less than or equal to 1.5 metabolic equivalents, or METs, which measures the amount of oxygen consumed while sitting at rest. One MET is equal to 3.5 ml of oxygen per kilogram of body weight per minute.
Young’s research interests at Kaiser Permanente include the conduct of physical activity intervention trials for adults and adolescents based in primary care clinics and community settings. She also studies how physical inactivity and excess sedentary time are associated with cardiovascular risk and risk factors.
Young is interested in health behaviors during the transition from adolescence to young adulthood and factors associated with maintaining physical activity, low sedentary time, and healthy weight status. Much of her work involves studying racial/ethnic minority groups to identify and reduce health disparities.
In the latest AHA statement, Young says it is not clear whether people should replace prolonged sedentary behavior with simple movement, or moderate to vigorous activity.
“There’s a lot of research that we need to do,” Young said. “This statement is important because it starts the ball rolling and suggests sedentary behavior may play an important role in heart health and more.”
